supernova

Cold, Hard Facts

milhayser — Fri, 27 Dec 2013 09:29:11 +0000

Cold, Hard Facts

Coldness can manifest where you least expect it: on a planet rapidly warmed by the combustion of fossil fuel, or in the heart of a star 250 times as massive as our own. On Greg Laden's Blog, Greg explains that an apparent "recovery" of Arctic sea ice from its historic low in 2012 does not invalidate the long-term trend. Greg also explains this year's legacy of extreme weather, such as snow in Cairo, writing that when there is less difference in temperature between equatorial and polar regions, "the jet streams get all wiggly and cause northerly air to reach far to the south in some places and southerly air to reach farther north in other places." Meanwhile, on Starts With a Bang, Ethan Siegel explores the different fates awaiting stars of different sizes. When a star like our own runs out of fuel and begins to collapse, it blows off its outer layers and leaves behind a neutron star or small black hole. Bigger stars, however, start producing antimatter, which lowers the pressure in the star and generates gamma rays that heat up the core even further. These stars end in a pair-instability supernova, which "not only destroys the outer layers of the star, but the core as well, leaving absolutely nothing behind!" But in the biggest stars in the universe, gamma rays cause photodisintegration, which cools down the interior of the star and allows all its mass to collapse into a black hole. The earliest of these massive black holes probably seeded the centers of galaxies, which now contain millions of solar masses.

milhayser Fri, 12/27/2013 - 04:29

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Misc

antimatter

Arctic Sea Ice

Black Holes

The Night the Universe Changed

esiegel — Wed, 06 Nov 2013 17:31:54 +0000

The Night the Universe Changed

"I conclude, therefore, that this star is not some kind of comet or a fiery meteor... but that it is a star shining in the firmament itself one that has never previously been seen before our time, in any age since the beginning of the world." -Tycho Brahe

I want to take you back in history, back to the middle of the 1500s. Night skies were spectacular, even from the world's most cosmopolitan cities, and thousands of stars consistently graced the sky, sights only visible from a few select locations in the world these days.

Image credit: Lennox & Addington County Dark Sky Viewing Area, via http://tamworth.ca/.

The positions, brightnesses and colors of each hitherto known star in the sky -- including all the nebulous and fuzzy objects visible to the naked eye -- were unchanged throughout the nights, years and centuries. Only the Moon and the five planets (Mercury, Venus, Mars, Jupiter and Saturn) changed their positions over time, relative to the fixed stellar-and-cosmic backdrop.

Image credit: Tunc Tezel of TWAN, via http://www.twanight.org/Tezel.

The motion of these wanderers through the night sky, along with eclipses and the orbits and appearances of comets, were the primary concerns of astronomers of that time. In particular, Copernicus' (posthumous) publication of his heliocentric model posed an interesting and controversial alternative to the favored Ptolemaic model, which had stood for more than a millennium.

But on this very night -- November 6^th -- some 441 years ago, something changed in the night sky that had never been recorded (in the Western Hemisphere) before: a new star appeared!

Image credit: Bob King (Astro Bob) of http://astrobob.areavoices.com/.

Not only did it appear on November 6^th, but it continued to brighten, eventually outshining all the other stars and planets in the sky and becoming visible in the daytime, before fading away from view over the span of two years. Tycho Brahe, the greatest naked-eye astronomer of all-time, noticed it that very first night. Looking back on it, he recalled,

When, according to habit, I was contemplating the stars in a clear sky, I noticed a new and unusual star, surpassing the other stars in brilliancy. There had never before been any star in that place in the sky.

He called it a "Stella Nova," latin for new star.

Image credit: Tycho Brahe, in his book "De Stella Nova".

For the first time, there was concrete evidence of the following:

The stars were not fixed, eternal and constant.
New stars could (apparently) be created. And finally...
Stars can (apparently) go away, too.

The most eternal things in all of human experience weren't eternal, after all. And nearly four centuries after Tycho's supernova first appeared, we discovered it all over again.

Image credit: VLA, NRAO, AUI, and NSF.

There's nothing like this in the visible part of the spectrum, of course, but when we turned our eyes towards the sky in radio frequencies (in 1952), the evidence was still there. What we found was a remnant from a long-gone star that had gone supernova some four centuries earlier.

And it isn't just in the radio that the evidence shows itself.

Image credit: NASA/JPL-Caltech/WISE Team.

In the far infrared, the warm gas blown spherically outward from this catastrophic stellar death is still visible, glowing at around 40 Kelvin.

You might take a look at the higher energies, too, and see if anything interesting showed up! We know that in many supernova explosions, the core can collapse down to form either a neutron star or a black hole, and in high energies (like X-rays), that would show up!

Image credit: High Energy Astronomy Observatory (HEAO-2) / Einstein Observatory / NASA.

Nothing! No central object, no extra high-energy sources at all.

This was no core-collapse (or Type II) supernova; this was a Type Ia, where a white dwarf star accrued enough mass that its degenerate core became unable to press back against the force of gravity, began to collapse, and initiated a runaway fusion reaction that destroyed the entire star! There's no collapsed object at the center, just high-energy material strewn about through the surrounding space.

Image credit: NASA / Chandra X-Ray Observatory.

X-ray imaging exposes this high-temperature gas, and spectroscopic imaging confirms for us what we suspect about objects such as this: the strong presence of heavy elements!

Image credit: ESA / XMM-Newton.

Even the highest energy radiation in the Universe -- the gamma rays -- get in on the action, and continue to shine brightly more than 400 years later.

Image credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS.

But white dwarf stars don't just "go supernova" on their own; they'd be eternally stable unless something were happening to increase their mass over time. There could have been a companion star to the one that went supernova in 1572, one that had mass siphoned from it onto the onetime white dwarf. Finding the center of the explosion was a challenge, but we have, in fact, been able to locate exactly where it took place.

Want to know if anything's there?

Image credit: NASA, ESA and P. Rioz-Lapuente (Barcelona) / Tom McMahon.

A G-class star -- the same class as our own -- is still there. Hundreds of years ago, this star was probably having mass siphoned off of it and onto its denser companion, when finally enough mass was accrued that the white dwarf became unstable, and a supernova ensued!

The star has moved by 2.6" (or about one-1,500^th of a degree) since the 1572 explosion, and is moving at a colossal 136 km/s relative to us, some three times the speed of all the other stars in its neighborhood. This star, more than any other, was given a boost (or a kick, if you prefer) by its onetime companion.

Image credit: William Herschel Telescope, WHT+UES, ISIS, AUX PORT CAMERA.

What remains now from that spectacular explosion is an expanding sphere of heavy elements, gas and dust, and a legacy that changed out understanding of the Universe forever.

Image credit: NASA / MPIA / Calar Alto Observatory, Oliver Krause et al.

In another few thousand years, all signs of an explosion will become invisible at all wavelengths, and eventually a fraction of these elements strewn into the Universe will make their way into future generations of stars and planets.

But that doesn't mean we'll never see the evidence from this star again!

Image credit: Subaru Telescope / NAOJ, Oliver Krause et al., 2008.

You see, the light from that spectacular explosion moved spherically outwards, and in a few places in the surrounding interstellar medium, reflects off the gas-and-dust that's found in space. And these "light echoes" occasionally make their way to Earth, allowing us to observe the supernova over and over again, so long as there's enough dust at the right distance and angle to send it our way.

Image credit: Subaru Telescope / NAOJ, Oliver Krause et al., 2008.

There have been -- and will be -- others, both in and beyond our galaxy since then, but if not for the supernova of 1572 (and a little later, the last naked-eye one, in 1604), it could have been a long, long time before the heavens held enough interest for us to look as deeply as we have.

Lucky us, for the Universe has been this way for all of human history, but on this night in 1572, our understanding of it began to change forever.

esiegel Wed, 11/06/2013 - 12:31

Tags

I'd be interested in knowing more about the cultural impacts of Tycho's Supernova, and if there are sufficient records from various parts of the world to assess how it affected different cultures.

---

Is there any estimate of the range of time it takes for dispersed heavy elements to condense and form planets? Or the number of stellar generations that might have elapsed from the Big Bang until the first planets could have been formed?

---

Re. the "increasingly rare" sight of the Milky Way and a sky full of stars: this suggests a project.

Amateur astronomers could equip themselves with battery-powered bullhorns, awaiting the next random local grid power outage. When the lights go out, they go outside and walk down the street, calling out to their neighbors through the bullhorn, "Come outside! Look at all the stars in the sky!"

For people who were born and raised in cities and suburbs with bad light pollution, going out and looking up during a blackout could get them interested in astronomy, space science in general, and for some people, possibly change their outlooks. All the better if their neighborhood astronomer was there to explain things and possibly set up a telescope for others to look at specific objects.

Nice article, Ethan!

May I make one and a half suggestions? Could you replace the phrase "Type I" with "Type Ia"? There are several sub-classes within Type I (Type Ib and Type Ic), only one of which has a white-dwarf progenitor.

Also, if it's possible -- and it may not be -- the two pictures which show Cassiopeia, one from a sky map and one from Tycho's journal, are rotated by about 180 degrees relative to each other. If they were shown with roughly the same orientation, it might be easier for readers to connect them.

Keep up the good work.

Michael,

I'll go halfsies with you. Type I is changed to Type Ia; I go back-and-forth because Type Ia and Type II are by far the two most common types I talk about here and I hate to bog people down with extraneous information when they don't need it (which is why I sometimes talk about asterisms as "constellations" even when I know it's technically wrong), but if I can teach people about the two types of "Type Ia" and "Type II" then that's both a very good thing and more accurate. So let's go with that.

But those two images of Cassiopeia show two different things: the first (Stellarium) shows the orientation of the Dipper, Polaris and Cassiopeia as they are after sunset at this time of year, while the second (Tycho's journal) shows exactly what Tycho drew. I could rotate either image to match the other, but if we can challenge people to delineate Type Ia from Type I, we can challenge them to use their spatial reasoning in this manner.

At least, that's what I think. :-)

Thanks for the catches and for the praise; you know I'll keep it up!

Re: G's comment (#3): this supernova was observed in Europe and in China and in Korea. You can read details in "The Historical Supernovae", by Clark and Stephenson. The only reference they provide to social reaction comes from Europe, and that is only among the educated elite.

By the way, Clark and Stephenson quote Tycho as writing that he did not see the new star on Nov 6, due to bad weather; he was able to glimpse it for the first time on Nov 11.

I really wanted to name my first son Tycho, but my wife nixed it due to pronunciation concerns. However, the story of his Brahe's somewhat ignominious demise didn't help convince her, either. http://www.huffingtonpost.com/2012/11/18/tycho-brahe-death-poison-bladd…

Man's understanding of the Universe has increased extremely rapidly in the last hundred years, or so, a very short time in the history of man, even in the 70 years of my own lifetime, but I expect we still have a long, long ways to go.

Re. Michael Richmond: Thanks for the book reference; I've copied it to my day-notes and will look for it.

I just today discovered "Starts with a Bang". It is great!

"The Night the Universe Changed" is missing an important element of Tycho as a scientist. Immediately upon seeing this new luminous object in the sky on November 11th 1572, he set about investigating what sort object it might be. In brief he determined two critical properties. The object was stationary relative to the other stars and it had no discernible parallax. Thus it had the properties of a star, namely it was stationary and much further away than the moon. It was these properties led him to call it "Stella Nova".

I forget to include a reference in my comment about Tycho as a scientist: "Tycho Brahe" by J. L. E Dryer 1890, p 38 ff

i have the feeling i'm missing something and maybe

am just too lost for you to help. still, if i could get an

answer from someone with enough knowledge to easily answer,

here's my question. Wasn't Tycho actually observing

not a new star but the exploding death of a white dwarf star?

which makes his discovery of the dynamic quality of the heavens

no less true, but coming from the opposite end of the birth-death

dynamic.

have i got it right or not? if so, i guess i've been thrown off by

the continuing strain of tycho's new star. let me know unless

i'm too lost to bother with.

Cosmic Bombardment of the Earth ca 2.2 Million Years Ago?

gregladen — Fri, 24 May 2013 17:31:10 +0000

Cosmic Bombardment of the Earth ca 2.2 Million Years Ago?

There are bacteria that use Iron (and other elements) to make tiny magnets that they carry around so they don't get lost. (I anthropomorphize slightly.) There are isotopes of Iron that are not of the Earth, but are found only elsewhere in the universe.

Suppose an event happened elsewhere and spewed some of that cosmic Iron isotope, say Fe-60, onto the earth, and the bacteria who were busy making their tiny compasses at that time used some of it. Then the bacteria died and were trapped inlayers in seafloor sediment and later examined by scientists looking for ... well, looking for evidence of cosmic events trapped in bacterial compasses!

Well, that happened.

A bit of sea floor was found to have Iron-60 in it a few years back. Iron-60 is radioactive and decays into Cobalt-60, with a known (but only recently known as it turns out) decay rate. That bit of rock was taken as possible evidence of an ancient supernova. The event was tied, conjecturally, to human evolution as all things must be whenever even remotely possible:

Cosmic fallout from an exploding star dusted the Earth about 2.8 million years ago, and may have triggered a change in climate that affected the course of human evolution. The evidence comes from an unusual form of iron that was blasted through space by a supernova before eventually settling into the rocky crust beneath the Pacific Ocean.

...

The team has now analysed a ... piece of ocean crust, where the supernova detritus is concentrated into a clear band of rock that can be accurately dated. The researchers found small but significant amounts of an isotope called iron-60 in the rock, which could only have come from a supernova.

"We've looked at all the possibilities and we can't find anything else that could produce such quantities," Korschinek says.

The human evolution impact idea comes from a possible cooling effect the exploding star would have had on the earth. Back in 2004 it was estimated that the earth would have been bathed in extra cosmic rays for about 100,000 years which would have, it was said, created condensation in the atmosphere which would have cooled the earth. There was a cooling event around that time (but quite possibly well after this date, so don't hang any hats on this) so I suppose this could be. But, I'm not going to assume that the cooling effects of cosmic rays are a thing at this point. I do know that people have gotten the effects of upper level vapor wrong a few times so I'm going to avoid making any assumptions about that here.

Anyway, last April, a paper was given at the American Physical Society conference giving preliminary findings related to some follow up research. Shawn Bishop and his team obtained a core from the Pacific dating to between 1.7 and 3. 3 million years ago. They sampled it at 100K intervals and extracted and separated out Iron in a way that would show Iron-60 if there was any. And ...

“It looks like there’s something there,” Bishop told reporters at the Denver meeting. The levels of iron-60 are minuscule, but the only place they seem to appear is in layers dated to around 2.2 million years ago.

And, the iron was concentrated in the target layers by the action of compass-using bacteria.

Notice the change in date from 2.8 to 2.2. This is, I think, because the half life of Iron-60 was refigured based on some intervening research. Now, the date is probably too late for a significant cooling event. But really, there were a whole bunch of cooling events from somewhere over 5 million years ago to about 2 point something million years ago, and there is a long list of candidates for what caused them, including numerous big volcanoes, continental movements, and now, a supernova.

I don't think anyone is claiming to know what star exploded.

___________________
Photo Credit for picture of fancy science machine: Gottfried not Bouillon via Compfight cc

gregladen Fri, 05/24/2013 - 13:31

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How to find your very own supernova

esiegel — Fri, 24 May 2013 14:50:27 +0000

How to find your very own supernova

"Do you see the absurdity of what I am? I can't even express these things properly because I have to - I have to conceptualize complex ideas in this stupid limiting spoken language! But I know I want to reach out with something other than these prehensile paws! And feel the wind of a supernova flowing over me!" -Ronald Moore

Well, you probably don't actually want to feel the wind of a supernova flowing over you; trust me on this.

Image credit: ESO / L. Calçada, of the remnant of SN 1987a.

But to find one for yourself, that's definitely within your reach, if you know where to look.

Supernovae come in a few distinct types, two of which are far more common than others.

Image credit: STSCI, NASA; NASA/T. Strohmayer (GSFC)/D. Berry (Chandra).

There are Type Ia supernovae, the most common type of supernova in our own galaxy. These occur when a white dwarf star -- either from mass siphoning, accretion, or mergers -- reaches above a certain mass threshold. When this occurs, the atoms at the center of the stellar corpse can no longer remain stable, and a runaway nuclear explosion occurs. The result -- as we've seen relatively recently in our galaxy -- is a fantastic supernova explosion that destroys the previously existing star!

Image credit: NASA/ESA/JHU/R.Sankrit & W.Blair.

But these types of supernovae -- the Type Ia -- can occur anywhere where white dwarf stars are located. Given that these are the second most common stellar-type object (behind red dwarf stars) in the Universe, at least for the next few hundred billion years (after which they'll eventually overtake red dwarfs), predicting where the next one will occur is a herculean task, well beyond what we know how to do.

But there is another type.

Image credit: Anglo-Australian Observatory, via Pete Challis.

When ultra-massive stars, or stars at least about eight times as massive as the Sun, exhaust the last of their nuclear fuel, the core of that star begins to collapse. Normally -- and this happens in stars like the Sun -- the forces between particles in the central region of the star are too strong for even gravity to overcome. This is true for nearly all classes of main-sequence star; our Sun is a run-of-the-mill G-class star.

Image credit: wikimedia commons user LucasVB.

But some stars are so massive -- all of the main-sequence O-stars and the brightest of the B-stars -- that the Pauli Exclusion Principle is insufficient to prevent core collapse, and this leads to a runaway reaction.

In the center of these stars, the core does in fact collapse, producing either a neutron star or black hole at the center, while the outer layers of the star are destroyed in a fantastic Type II supernova explosion!

The thing is, stars like this are very, very rare; less than 0.1% of all stars are massive enough for this to happen. Furthermore, stars that are this massive live for such short amounts of time before burning through all of their fuel.

But this is great, because it tells us something: if you want to find one of these Type II supernovae, you're way more likely to get one if you look at a young, star-forming region of space!

Image credit: NASA,ESA, M. Robberto (STScI/ESA), HST Orion Treasury Project Team.

We have a few of these star forming regions in our own galaxy, of course, perhaps the most famous of which is the Great Orion Nebula, prominently visible during the winter months.

But you don't mine for gold in a tiny vein when there are giant ones to go after, and you don't look for supernovae in HII-regions of relatively quiet galaxies when there are places in space so active that the entire galaxy in question is a star-forming region!

Image credit: NASA / JPL-Caltech / STScI / CXC / UofA / ESA / AURA / JHU.

The easiest way to get a galaxy that forms stars this rapidly is when two relatively equal-sized galaxies merge. The gravitational interaction causes large amounts of the gas in both progenitor galaxies to contract down and form new stars. When this happens, the star formation rate can become tens, hundreds or (possibly) even thousands of times as great as it is in our own Milky Way.

While the vast majority of stars (99.9%+) created will be too low in mass to go supernovae, you don't really care about that when you're creating millions (or hundreds of millions) of stars. Eventually, one of them is going to blow.

Image credit: flickr user yu244720, a.k.a. (Robert) Sean Davies.

If you hear about it, and you know where to look, you can, of course, see it for yourself.

But if you're really lucky, you can be the one looking at the right time to discover it! In fact, amateur astronomer supernova hunters can, individually, discover dozens of new supernovae on their own. The best place to look? You guessed it: merging and interacting galaxies!

Image credit: NASA, ESA, the Hubble Heritage Team and A. Evans.

These are the cosmic hotbeds of star formation, and hence they're also the most prolific cosmic supernova factories. But looking at any one galaxy in particular, just once, isn't going to tell you very much. (Even if it's one of the most active galaxies in the entire known Universe.)

Image credit: NASA/ESA/Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration.

That's because what you need to do is find a galaxy and compare it to earlier images of that same galaxy. It's only when you get an unexpected brightening -- a rapid, extreme brightening -- that rises and falls over the span of many days, that you've got a candidate for a supernova.

And if you find one, that only means you've got a candidate supernova. For confirmation, you need spectroscopic follow-up, and that almost always requires the attention of a professional.

Image credit: NASA / JPL-Caltech / STScI-ESA / S. Bush, et al. (Harvard-Smithsonian CfA).

This Hubble/Spitzer composite image shows the mammoth galaxy NGC 6240, an ultraluminous galaxy in the process of a major merger. Recently, astronomy outreach expert Adam Block took this spectacular wide-field image of this galaxy. The sight is spectacular, and (like for all images here) you can click for a full-resolution image in all its majesty.

Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona.

Even though this galaxy is certainly undergoing higher-than-average rates of star-formation, it certainly isn't obvious that anything out-of-the-ordinary has happened here.

But something's worth checking out. Let's take a look at the highest-resolution Hubble image available of this galaxy, and in particular, I want you to focus on the star-forming region I've outlined in orange, below.

Image credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University).

This region is one of the hotbeds of star-formation. I mean, the whole galaxy is, but the blue reflection nebula tells you that there are some extraordinary hot, blue stars in there, as well as some neutral gas/dust, which reflects the light from those hot, blue stars.

The thing is, that image is from years ago. Let me take you inside Adam Block's image, now, and see if you can find anything interesting.

Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona.

Look hard, detectives. Let me help you out, with a little zooming, cropping, and a couple of arrows.

Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona (bottom), NASA / ESA / Hubble Heritage Team / A. Evans (top).

That has got to be a supernova! It's almost definitely a Type II, based on where it's happening, and even though it's probably a rather uninteresting one now that it's almost certainly on the decline (I believe the image dates from April 11th), if you happen to be a professional out there just twiddling your thumbs with clear skies and no targets of interest, take a spectrum of this and give Adam Block, who's created some of the most spectacular astroimages I've ever seen, his first supernova discovery!

Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona.

And if you happen to be looking -- with the right equipment, in the right place, at the right time -- you, too, could find one of these for yourself!

esiegel Fri, 05/24/2013 - 10:50

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Ethan,

This subject is near and dear to my heart, since I performed a supernova search as part of my dissertation. Let me warn prospective searchers that this is not a job for the faint of heart or short of patience. I observed once every two weeks for about two years, concentrating on galaxies with enhanced star formation rates, and found only 3 SNe in a sample of about 150 galaxies .... and in each case, someone else found it first. Sigh.

By the way, Type Ia are _not_ the most common supernovae in the Milky Way, based on all the evidence. The Milky Way is an Sb or Sc spiral, and surveys of other galaxies (for example,

http://arxiv.org/abs/1006.4613

show clearly that core-collapse supernova occur 2-4 times more frequently than SNe Ia in spirals of this sort.

Michael,

Ah, the bias of basing a conclusion like that on what we've seen for the past few thousand years! That is a very cool study; thanks for sharing!

So Type II supernovae are far less common in Milky Way type galaxies than they are in starburst (or other accelerated SFR) galaxies, but that still outpaces the Type Ias. Interesting!

Probably the greater amount of dust in spiral type galaxies explains that difference. More dust to collapse, bigger stars, more likely they're the size that goes boom because they fall in to themselves.

I *love* hindvision..!

Messier Monday: The First Messier Supernova of 2013, M65

esiegel — Mon, 25 Mar 2013 16:56:53 +0000

Messier Monday: The First Messier Supernova of 2013, M65

"I wouldn't dream of working on something that didn't make my gut rumble and my heart want to explode." -Kate Winslet

Welcome back for another Messier Monday! At the start of each week, we take a detailed look at one of the 110 deep-sky objects that make up the Messier Catalogue. This week, we've got a very special happening in the night sky to introduce you to.

Image credit: Tenho Tuomi, Saskatchewan, Canada.

One of the most common class of object in the Messier Catalogue are galaxies external to our own Milky Way, which make up a whopping 40 of these 110 objects. Occasionally -- a little more than about once-per-century -- a supernova will explode in a typical, Milky-Way-sized galaxy. Although we haven't seen one in our own skies in over 400 years, we've witnessed a total of 54 supernovae in these known Messier galaxies, with 25-out-of-40 of these galaxies having been caught in the act of having at least one supernova since we've started looking.

Well, as of 3 days ago, you can add one more to each list: Messier 65! Here's how to find this galaxy, with more details to come!

Image credit: Me, made with the free software Stellarium, via http://stellarium.org/.

Beneath the Big Dipper -- below the cup-and-handle -- you'll find the well-known constellation of Leo the Lion. Tonight, the Moon will near the bright star, Denebola. Back towards Regulus -- the brightest star in Leo -- you can find the somewhat dimmer naked-eye star, Chertan. And, if you wait a few days for the Moon to move out of the way, the faint, nearly edge-on spiral of M65 will be visible through even a decent pair of binoculars, if you know where to look!

Image credit: Me, made with the free software Stellarium, via http://stellarium.org/.

Just three degrees away from the blue star Chertan (and a mere one degree away from the still-naked-eye star, 73 Leonis), you'll be able find this spiral galaxy in just a few nights, as soon as the Moon is out of the way in the night sky.

Image credit: Gianluca Masi and the EU's Virtual Telescope Project.

The bright stars you see are from our own galaxy, but Messier 65's bright, central nucleus and sweeping dust lanes are clearly visible in this exposure. For those of you who have some wide-field equipment, Messier 65 will be one of the dominant extended objects you see as part of the famed Leo Triplet, shown in this 4.4-degree field-of-view exposure, below!

Image credit: ESO and Digitized Sky Survey 2.

Messier 65 is the extended galaxy farthest to the right in the image above of the triplet, which are very clearly gravitationally bound to one another. Although all three galaxies are approximately 35 million light years away, they don't appear to be interacting gravitationally with one another, suggesting that -- much like for us and Andromeda -- a gravitational merger is likely lurking in the future for this group!

A closer investigation reveals the majesty of these three objects.

Image credit: ESO/INAF-VST/OmegaCAM. Ack: OmegaCen/Astro-WISE/Kapteyn Institute.

Interestingly, Messier 65 and the other compact, bright spiral in the triplet, Messier 66, were both discovered by Charles Messier himself on March 1st, 1780, but the third member of the triplet -- despite having a nearly identical brightness -- eluded him!

The triplet is often photographed together by amateur astronomers, and makes for a glorious sight.

Image credit: Hunter Wilson, a.k.a. Hewholooks of Wikimedia Commons.

Photos of this nearly edge-on spiral grace many corners of the web, including Volker Wendel's site, where he captures M65 in outstanding detail.

Image credit: Volker Wendel of http://www.spiegelteam.de/.

Alvin of LightBuckets spent over 18 hours imaging M65 along with its nearest galactic neighbor, M66, with a 20" telescope to produce this masterpiece, below.

Image credit: administrator/user Alvin of http://www.lightbuckets.com/.

Of course, a professional telescope can do a little better. Normally, Hubble provides the best views of a galaxy (when available), and even though this image was taken with the old WFPC2 camera, it's still an outstanding shot, of this galaxy's nucleus. (In unprecedented high-resolution, as only Hubble can deliver.)

Image credit: NASA / ESA / STScI / AURA / Hubble Space Telescope.

And -- for a nice, focused view of the entire galaxy -- here's what the European Southern Observatory sees when it images M65.

Image credit: ESO/INAF-VST/OmegaCAM. Ack: OmegaCen/Astro-WISE/Kapteyn Institute.

Pay attention to the level of detail, here, and remember that practically every "point" of light you see is a star from within our own galaxy, while the stars of Messier 65 itself are visible as mere fuzzballs. You'll notice that, lined up with the core of the galaxy -- appearing to extend directly "down" from it -- are two foreground stars that are part of our own galaxy, while just slightly "upwards" of the 3 o'clock position, in a chance alignment with the sweeping arm structure of the galaxy, is another, dimmer star.

Why do I bring these details to your attention? Because just three days ago, an announcement was made. M. Sugano, from Kakogawa, Japan, took the following photograph that shows a new star in this galaxy, where none was previously seen. Have a look for yourself!

Image credit: M. Sugano, Kakogawa, Hyogo-ken, Japan.

Do you see it? I've zoomed in an added a circle, to help show you where to look.

Image credit: M. Sugano, Kakogawa, Hyogo-ken, Japan, circle by me.

That extra "point of light" is a supernova! Now confirmed, it will henceforth be known as SN 2013am, and is the first supernova to go off in a Messier Object this year! More images, as they become available, will appear here, and as soon as the Moon moves out of the way, those of you interested in supernova-hunting will have your opportunity to see this object yourself!

It's expected to brighten to a maximum of magnitude 11, which means anyone with even a modest telescope should be able to find it without a problem! In fact, if it does reach magnitude 11, it will be about 20% as the entire rest of the galaxy, combined!

And the best image I've seen so far? That's Manfred Mrotzek's, shown below.

Image credit: flickr user Manfred Mrotzek.

And that's a wonderful way to end this Messier Monday with a bang! Including today, here are the Messier objects we've taken a look at so far:

M1, The Crab Nebula: October 22, 2012
M8, The Lagoon Nebula: November 5, 2012
M13, The Great Globular Cluster in Hercules: December 31, 2012
M15, An Ancient Globular Cluster: November 12, 2012
M30, A Straggling Globular Cluster: November 26, 2012
M33, The Triangulum Galaxy: February 25, 2013
M37, A Rich Open Star Cluster: December 3, 2012
M41, The Dog Star’s Secret Neighbor: January 7, 2013
M44, The Beehive Cluster / Praesepe: December 24, 2012
M45, The Pleiades: October 29, 2012
M48, A Lost-and-Found Star Cluster: February 11, 2013
M52, A Star Cluster on the Bubble: March 4, 2013
M53, The Most Northern Galactic Globular: February 18, 2013
M60, The Gateway Galaxy to Virgo: February 4, 2013
M65, The First Messier Supernova of 2013: March 25, 2013
M67, Messier’s Oldest Open Cluster: January 14, 2013
M72, A Diffuse, Distant Globular at the End-of-the-Marathon: March 18, 2013
M74, The Phantom Galaxy at the Beginning-of-the-Marathon: March 11, 2013
M78, A Reflection Nebula: December 10, 2012
M81, Bode’s Galaxy: November 19, 2012
M83, The Southern Pinwheel Galaxy, January 21, 2013
M97, The Owl Nebula, January 28, 2013
M102, A Great Galactic Controversy: December 17, 2012

Come back next week, where we'll learn about a new deep-sky object here, on another Messier Monday!

esiegel Mon, 03/25/2013 - 12:56

Tags

Hi Ethan

Where is there a list of SNs? I'm interested in seeing how many new SNs are detected per year. I assume the numbers/yr are increasing due to improved instrumentation/computing

The Central Bureau for Astronomical Telegrams keeps a list of all the supernovae which have been announced in its telegrams:

http://www.cbat.eps.harvard.edu/lists/Supernovae.html

The number found per year has risen since the 1970s and 1980s, but it has also fallen a bit in recent years as certain supernova search teams end their efforts.

Thank you Michael R.

Ethan, how far away would we have to be to remain comfortable if one of these were to go off in our own galaxy? Are there any known candidates ready to go within the next 100k years? What would it look like from here if they popped?

Betelgeuse is the well known one. Eta Carinae is even bigger but further away by a fair old bit.

Both are going supernova "any time now", but that's on a stellar timescale, so maybe thousands and thousands of years.

Betelgeuse at 430 light years is probably far enough away. If it were 60 light years, we'd be in trouble but unless there's a jet and we're along it (it won't: it's pole is pointed well away from us), 430 light years is safe enough.

I keep seeing the 11th magnitude prediction, but I think there may be a problem with that. The SN does not seem to be brightening much, plus per ATel #4910: "These weak Swift UV detections confirm a significant extinction, in agreement with the reddened optical spectrum (as also reported by ATel #4909)."

"Significant extinction" needs to be defined. I was hoping to see this SN the second week in April during a Messier Marathon, but I'm beginning to doubt that will happen. After 34 years of Marathons, last year was the first time there was a supernova in an M object during the Marathon. This would have made two years in a row.

At about 2230 hrs EST on 5-20-2013, I observed a very bright light in the sky just to the right of the Big Dipper. The light increased in brightness then faded and went out. What did I see? I think it was a supernova. It was pretty cool and it was my first. I did not have any visual aid. Just happened to look up while out in the yard.

I now live on Molokai, and either the night of the 26 th or 27 th of May 2013 my daughter and I were sitting on the patio at approx. 9:30 pm. We observed a series of very bright flashes white in nature, and at intervals of approx. 20 seconds apart. This occurred about five times almost directly overhead. This was not a satellite or aircraft, I am a pilot and have flown over 20,000 hours for the state of Arizona, I know the difference. It was so intense that it frighten my daughter who is 44 yrs of age.

Just wondering if anyone else observed such a sighting, about the same time.

Giving thanks for our place in the Universe

esiegel — Wed, 21 Nov 2012 15:51:09 +0000

Giving thanks for our place in the Universe

“We live in an atmosphere of shame. We are ashamed of everything that is real about us; ashamed of ourselves, of our relatives, of our incomes, of our accents, of our opinions, of our experience, just as we are ashamed of our naked skins.” -George Bernard Shaw

All that is real about ourselves is nothing to be ashamed about; quite to the contrary, it's something to be eminently thankful for. This very existence is all we have, and while it's minuscule compared to the entire Universe, it required the entire Universe to bring us to the point where it's possible for us to exist.

What do I mean by that?

I mean that everything we've ever known about our existence owes its origins to something far grander than our experiences here on Earth would have us believe. Yes, it's true that our experiences on Earth, stemming from the very first proto-cell ever to reproduce itself billions of years ago, whose legacy is encoded in the nucleic acids of every creature in existence today, provide us with a remarkable and rich natural history that managed to lead to us. Without the events of the past four billion years on Earth, each one of us, to say nothing of the trillions of generations of living creatures that we're descended from, would never have existed.

Image credit & copyright: Leonard Eisenberg, 2008, of http://evogeneao.com/.

(The turkey that many of us will be eating tomorrow is perhaps our 160,000,000th cousin, some 50,000,000 times removed.)

But those same atoms that now make us up -- that millions of years ago made up our ancestors -- have been around on our planet since its birth, some 4.5 billion years ago.

Image credit: ESA / Rosetta Spacecraft.

And where did those atoms come from?

Practically all of the atoms we find on Earth: Nitrogen, Oxygen, Carbon, Iron, Silicon, Sulphur, Nickel, Magnesium and Calcium -- over 99% of the atoms on our planet -- were once inside of a star that went through its entire life cycle, burned up all of its nuclear fuel, and died in a spectacular supernova explosion.

Image credit: NASA / JPL-Caltech / S. Stolovy (SSC/Caltech).

That burned-up fuel from prior generations of stars that lived and died created practically all the heavy elements -- every single atom heavier than element #4, Beryllium -- that exists in the Universe today. Only after multiple generations of stars, living and dying, their fused atoms recycled into star-forming regions rich in unburned hydrogen and helium, could a star system like ours, complete with rocky planets and the ingredients for life, be formed.

Image credit: GIMP user and astronomer Griatch; http://tinyurl.com/GriatchAstro.

In order for those stars to exist, burn, recycle their elements, and eventually form successive generations containing planets, heavy elements, and life, it required a Universe full of massive galaxies, loaded with the light elements capable of forming stars in the first place.

Image credit: NASA, ESA, M. Postman (STScI), and the CLASH Team.

The galaxies themselves, great cosmic spirals, ellipticals, and irregular behemonths, collections of billions or even trillions of suns' worth of matter, are the gifts of a matter-filled Universe operating under the laws of gravity. Given the history of the Universe, some small fluctuations away from a perfectly uniform density, and general relativity, gravitation ensures that you'll get a Universe filled with hundreds of billions of galaxies, each containing, on average, hundreds of billions of stars.

It took the first 9 billion years of stars forming and galaxies merging and growing to set the stage to form our Solar System and the planet that we all call home. And it took the entire Universe, complete with our expanding spacetime and the laws of physics that govern everything that exists, to do it.

Image credit: NASA, ESA, Hubble Heritage Team (STScI / AURA); J. Blakeslee.

And what's amazing is that -- if you're willing to start with expanding spacetime and the laws of physics -- a Universe that looks a whole lot like ours, complete with clusters, galaxies, stars, planets, heavy elements, and, most probably, life, is inevitable. And it's inevitable all over the Universe.

Image credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration.

So don't be ashamed of what you are; be thankful for all that you are!

Tomorrow (Thursday) marks American Thanksgiving, an annual harvest festival and feast where we celebrate a variety of things, particularly the good things that have come to us in life. While I myself have a great number of personal things to be thankful for, including six wonderful years with my partner, Jamie, and nearly five years of sharing this Universe with you here at Starts With A Bang, the story of where we come from is universal to us all, and it's something we can all be thankful for together.

Image credit: HD Desktop Wallpapers, of Snake River in Grand Teton National Park.

Happy Thanksgiving to each and every one of you out there -- whether you celebrate it or not -- and may your lives be filled with a wonderful bounty of things to be thankful for, today and all the days of the year!

esiegel Wed, 11/21/2012 - 10:51

Tags

Happy Thanksgiving to you and yours, and thanks for the wonderful blog!!

Your thanksgiving blog is indeed magnificent! To me "God" and "Universe" are equivalent terms and so let me wholeheartedly join you in this Thanksgiving.

Better than any pray I'll be forced into listening to today. Thankyou. I love the Shaw quote.

Thanks, and thanks for your ongoing creativity on this blog, and very best wishes!

Family, friends, good rational people, enthusiastic teachers like Ethan. There are a lot of candles in the dark to thank for lighting our journey through this fascinating place.

How do you get matter from an exploding star to reconverge into things such as planets, complete with angular velocity/rotation?

Collisions.

Some lose energy and leave, some gain and fall in.

Thank you for the inspiring reminder. May I never be distracted from our wonderfully infinite and eternal Being-in Love....

Thank you and happy thanksgiving! Today I am thankful for my existence, my family, friends, good health, and this blog!

Uh that should have been the other way round.

For those who feel like the universe is trying to kill them.It probably is.You can't get out of the universe either.And time is never going to end. I don't envy them and its because I am in a better position.For this I am greatful.

Shame has been used by the elite to control. That doesn't mean, however, that humans should abandon the very real and useful tool of shame. There ARE very real reasons one should be ashamed: such as lying, cheating, stealing, etc. Unfortunately, articles such as this simply re-inforce the new age notion that we should abandon all shame: which leads to a free for all of "anything goes."

The analogy is our relationship to anger. Our culture has given us the notion that anger=violence, which it does not. However, that brainwashing has successfully stripped us of our sense of justice and taking action based on the outrages of inequality.

DISCERNMENT is key in understanding the nuances of all of the natural emotions of humans. I'd like to see a bit more going on here in this article.

I am most thankful for the work that you and all scientists do, and particularly for this blog in which you make it accessible and understandable for lay people like myself.

"Unfortunately, articles such as this simply re-inforce the new age notion that we should abandon all shame"

OK, I'm confused.

Where does it say that? Or should you feel ashamed for posting to the wrong thread?

May all praise and glory be given to our heavenly father, Jehovah. He created all things in existence, through his son Jesus Christ and for his son.

A cascade of ecological events with unforeseen consequences is occurring around us. There are multiple causes. But human overpopulation of Earth is the prime factor.

Not really.

USA have a per-person footprint 6x the average.

I.e. maybe 8x the mode.

If the USA went to the average (and everyone above the average did so too), we'd have the ecological footprint for many things of a planetary population around a billion.

Are you maintaining that the planet cannot handle a billion people?

Thaks for this blog!! great story.. and great evo chart.. I took my son to the American Natural History Museum for Thanksgiving!

Well, I've been wanting to say "thanks" to Ethan for his new comment policy. It's helped to keep discussions on the point of the post and science and civil. So thanks Ethan.

It's so nice to see people communicate civilly. fundamentally, I believe in and like people. All kinds of people. People and relationships (e.g. through their activities in arts, science, play and ideas, etc. family, friendship, nature) are the real riches, the only richness to be desired and values.

So thanks Ethan for your excellent and welcoming blog. Yes this blog is a very welcome place to listen, learn, participate with seriousness, or humor, to join in wonderful astrophysics (i.e. human) discussion.

As to giving thanks for my place in the universe, who exactly am I thanking? Ahh yes, each you. Yes you friend, family, adversary, whether near or far, whether physical, virtual and/or psuedononimous (is that a word, well it is now).

Yes it is you, each personally, to whom I give thanks.
My toast to each of you, "To you, all the best.".

Hey Chris Bush,

To those of us who don't believe your creation myths, I suppose eternal torment in Hell awaits us.

Your Jehovah is not worth believing in.

Where do Type Ia Supernovae come from?

esiegel — Thu, 08 Nov 2012 17:28:07 +0000

Where do Type Ia Supernovae come from?

"You have to have a canon so the next generation can come along and explode it." -Henry Louis Gates

When it comes to stars, their fates are very well known. Every single star that's massive enough to fuse hydrogen into helium in its core will someday run out of fuel and die.

Image credit: NASA, ESA, F. Paresce, R. O'Connell, & the HST WFC3 Science Oversight Committee.

The very brightest and most massive stars -- about 1-in-800 of all stars -- will die in a spectacular, core-collapse supernova when their core burns fuel all the way through iron and finally runs out of room to go.

This kind of supernova explosion, a Type II supernova explosion, is the second most common in the Universe. But for the other 799-out-of-800 stars, their fate is much gentler.

When they run out of fuel, however long it takes and whatever element it stops at, the core of the star (or the entire star, in the case of an M-class star) contracts down to a degenerate mass of atoms, held up only by the Pauli Exclusion Principle, preventing the electrons in the atoms from getting any closer together.

Image credit: ESA/NASA.

This results in an object that's about the physical size of planet Earth, but about the mass of an entire star, some 300,000 times denser than Earth. That's what a white dwarf star is.

And for some of these white dwarfs, this is the end of the line. Over time, they'll cool and radiate energy away, finally dimming out and becoming ultra-cold black dwarfs, on timescales of at least quadrillions of years.

But some of these white dwarfs will get a second chance to make their voices heard across the cosmos.

Image credit: NASA / JPL-Caltech / CXC / Calar Alto O. Krause (MPIA).

A different type of supernova -- a Type Ia supernova -- can happen if the circumstances are right. You see, the reason that the heaviest-mass stars become a Type II supernova is because the atoms in the core, even with the Pauli Exclusion Principle, cannot stand up against collapse.

The very atoms in the core are subject to tremendous outside pressures, and if the core itself -- no longer fusing any elements and thus devoid of new radiation -- is too massive, it will have no choice but to collapse even further.

Image credit: Wikimedia user Spacepotato.

In the case of a normal atoms (as in a white dwarf star), this will happen if the mass reaches or exceeds about 1.4 solar masses, known as the Chandrasekhar mass limit.

If a white dwarf star acquires enough mass that this limit is exceeded, or that some other process creates too strong of a pressure at the core, a runaway fusion reaction occurs, destroying the entire white dwarf in a catastrophic Type Ia supernova.

Image credit: NASA, ESA, Zolt Levay (STScI).

Above is the remnant of the Supernova first observed on Earth in 1006, the brightest ever recorded in history. This composite image (including X-ray data on the interior) shows what happens in the aftermath of such an event.

These Type Ia supernovae are the most abundant type of supernovae in the Universe. But the question remains, how do these events occur? First off, it's pretty clear that these events are not all identical. Because the laws of physics are the same everywhere, if all Type Ia supernovae were identical, the light curves of each of them would be identical. And they're similar, but there's quite a bit of variety.

Image credit: J. Nordin et al., 2010, from http://arxiv.org/abs/1011.6227v1.

It used to be thought that these supernovae came about because, in binary star systems, the very dense white dwarf could siphon mass off from its companion star, doing so until it eventually exceeded this Chandrasekhar mass limit. And then, when the white dwarf got too massive, the atoms in the core would give way, there'd be a runaway fusion reaction, and a Type Ia supernova would result.

Image credit: ESO / M. Kornmesser.

But this process would be far too rare, and also far too uniform, to explain the Type Ia supernovae that we presently see.

At this point in the Universe, white dwarfs have already become the second most abundant type of star around. So a second possibility was brought up: perhaps two white dwarf stars spiral into one another, and will eventually merge, exceeding the Chandrasekhar mass limit when they do! (Video may trigger seizures in epileptics; audio is based on the frequency of gravitational radiation.)

But this may not be the only way to do it, either. Even though we have observed inspiraling pairs of white dwarfs, they, too, may not exist with high enough frequencies to explain the supernovae rates we observe. Even more damning, however, is that the details of the spectra do not match the models!

But a new theory proposed by J. Craig Wheeler -- the White Widow model -- just might be the solution to where the majority of these supernovae come from.

Image credit: NASA, ESA, CXC, SAO, the Hubble Heritage Team (STScI/AURA), and J. Hughes.

Rather than a slow siphoning of mass or a rare white dwarf-white dwarf inspiral, these supernovae could be caused by interstellar collisions between white dwarfs and other, normal stars, including the most abundant of stars, the class-M red dwarfs.

Image credit: NN Serpentis by the University of Warwick.

As Wheeler himself says:

"I believe that the spectra have to be respected. The really high-order constraint [on a supernova model] is to get the spectral evolution correct. That is, you've got to get all the bumps and wiggles, and they've got to be in the right place at the right times."

Because all you have to do is create an instability in the core of this white dwarf, and runaway fusion will undoubtedly occur all over the star, as the following simulation of a white dwarf's temperature and density shows nicely.

So, is this the way it actually happens? It's going to take more research to find out, but this is an outstanding possibility that illustrates the sheer variety that the Universe undertakes when creating even these "standard candles," the very ones that were used to first discover dark energy!

I'll likely be out of touch for the next few days while I'm at Carl Sagan Day (remember?), so for those of you who can make it, I hope to see you there, and for those who can't, I'll be back on Monday!

esiegel Thu, 11/08/2012 - 12:28

Tags

Great explanation of this exciting new research.
I'll have to reread the links, but it seems like excellent research.
Thanks, Ethan
And enjoy Carl Sagan Day

"In the case of a normal atoms (as in a white dwarf star), this will happen if the mass reaches or exceeds about 1.4 solar masses, known as the Chandrasekhar mass limit.
If a white dwarf star acquires enough mass that this limit is exceeded, or that some other process creates too strong of a pressure at the core, a runaway fusion reaction occurs, destroying the entire white dwarf in a catastrophic Type Ia supernova."

You're confusing two issues. When Chandrasekhar limit is reached, a white dwarf collapses into a neutron star. That's it, there might not be any further fusion. The main energy source of the supernovae in this case is good old gravitational potential energy (fusion of electrons and protons releases some energy in form of neutrinos, but its impact is fairly small).

However, recent models point out that this in fact does NOT happen in most Ia supernovae. Instead, _just_ _before_ the Chandrasekhar limit is reached carbon burning is ignited. This burning happens catastrophically, releasing enough energy to totally unbind the star. There's literally nothing left after the explosion: no white dwarf, no neutron star, no planetary system.

Alex, those models are probably wrong.

At least if they're saying nothing is left. Which I doubt, but could be true of some models.

When the carbon shell ignites, there will be a lot of the mass that would form a neutron star thrown off instead because that mass is in the carbon shell and half of that mass is outside the median of that shell. This could easily be thrown off.

But the stuff closer to the star's centre than the median?

Thrown inward.

I thought the case against Ia origins included calculations that mass transfer from companion to binary would make far too many x-ray binary sources, especially if the WD initial mass was only 0.6Msun, which is typical WD mass. Does the White Widow model get around this problem?

If I understand the models correctly, it's not just a shell that detonates, but the entire star. A shock wave spreads out from the point where detonation is initiated, so that even if some of the mass is thrown inward, it still engages in fusion due to the enhanced pressure of the shock wave. Eventually the shock front reaches the center of the star, and it is no longer possible to throw mass inward. Thus, as Marvin the Martian would say, an Earth-shattering kaboom.

The Chandrasekhar limit applies when degeneracy pressure is the only thing counteracting gravity. Depending how the contraction or collapse occurs, you could get enough pressure in places to produce an exothermic fusion reaction (because the original star was never heavy enough to produce an iron core).

It's a bit of "neither is entirely wrong", Eric.

From what I remember, stars will sort of fractionate their fusion products (largely). This causes shells of Hydrogen, Helium, Carbon, Oxygen, etc.

The energy released per unit time for a fusion reaction goes up quickly with temperature (can't remember the order for H-H fusion, but the steps are right). T is temperature

H-H ~ T^8
He-He ~ T^14
C-C ~ T^16

So the reactions are very low (practically zero) at low temperatures but soon after they become possible, they quickly outpace the energy production of the slower increasing lighter element fusion.

That means when you get fusion in the Carbon shell, you get a LOT of fusion (there are all the upper layers holding it in).

Boom.

Of course, the extra boom from below causes even more fusion in the higher levels. Each introduce their own boom.

So it's a bit of both.

Lately I've been wondering how chunky the material blown out of a supernova is. Is the explosion just a mist of vaporized particles, or are there sizable chunks of metals and other solids as well? How large might one of these core fragments conceivably be? I would speculate the size distribution follows a power law function, but that's just a guess. If it is a mist of vaporized particles, then how would iron asteroids consolodate and form?

Can anyone comment on this?

Alan, have a look at the Veil Nebula, the result of a nearby supernova.

http://en.wikipedia.org/wiki/Veil_Nebula

As to your question: gas clouds collapse. If they collapse into smaller lumps, they only form planets. Bigger lumps, stars.

If a star forms from a collapse, the photon pressure from the star will strip away the gas cloud and stop much more collapse happening, hence in our solar system, where the inner planets didn't form in a dense area of cloud, we only have the rocky planets, wheras jupiter could gain weight quick enough to retain Hydrogen and Helium and ate up a lot of extra mass before the sun grew bright enough to stop it.

Thanks for the response Wow, but I don't think this addresses my question at all. I'm familiar with the basics of planetary evolution, and that wasn't what I was asking about.

My question was: Is there any "schrapnel" from a supernova explosion, or is it purely a hot gas of particles?

Alan,

There is -- in a Type Ia -- possibly sometimes some shrapnel, as you put it. Take a look at SN 1006, for example. Yes, there's the diffuse gas inside the bubble, but there's also a thin "ribbon" of dense matter at just one location on the bubble surface. (See here.)

The remnant of Kepler's supernova (SN 1604) also shows a similar visual "firework" structure, here.

It is unclear if this is the shockwave slamming into gas from the interstellar medium, or if this is shrapnel from the original explosion itself, but either way this is clearly more than just a "diffuse gas". Type Ia's tend to be roughly spherical, however, with most of the energy contained in the "bubble walls" as far as we can tell.

Sorry this isn't a definitive answer, but I hope it addresses some of your concerns.

Wow,

"At least if they’re saying nothing is left. Which I doubt, but could be true of some models.'
Sure, in other scenarios neutron star remains.

"When the carbon shell ignites, there will be a lot of the mass that would form a neutron star thrown off instead because that mass is in the carbon shell and half of that mass is outside the median of that shell. "

Again, you're thinking about a normal star. We're talking about a white dwarf, it doesn't have enough MASS to become a neutron star. Also, it's very homogeneous because it mostly consists of a carbon ash from a star core, there are no distinctive shells. There's a thin crust of helium and hydrogen on the surface, but we can safely ignore it.

Also, white dwarves are supported by degeneracy pressure so there are two additional compounding factors - degenerate matter is incompressible and it is very heat conductive.

So once carbon burning starts (models show that it happens near the center of the star) you have a perfect storm. The burning wave actually initially moves faster than the speed of sound (which is a good percent of lightspeed at these frequences!), so it's really an earth-shattering detonation.

"Again, you’re thinking about a normal star. We’re talking about a white dwarf,"

We can't be.

A white dwarf doesn't go nova. Or supernova. Or collapse. It IS collapsed. White dwarf is the end point.

If this post is indicative of your understanding of stellar evolution, you need to get back to Astrophysics 101.

Thanks Alex for provide "up-to-date" info on white dwarfs and pointing out that they explode just below the Chandrasekhar limit. As Dr. Wheeler said, the idea of the limit being exceeded causing the dwarf to explode is appealing, easy to visualize but wrong for the past 50 years. Ethan please take note, Cosmic Catastrophes, 2nd Ed, Dr. J.Craig Wheeler, pg 104. ;)

Also, I read the press release. It doesn't support your interpretation of the triggering mechanism of Ia supernovas, .i.e., "interstellar collisions between white dwarfs and other, normal stars".

Rather, Wheeler is just saying that instead of an evolved red-giant or another CO white dwarf, the companion star to the white dwarf is a class-M dwarf.

Wow,

"A white dwarf doesn’t go nova. Or supernova. Or collapse. It IS collapsed. White dwarf is the end point."

It can't do these things in _itself_. However, it can accrete matter from a companion star. If it accretes matter slow enough then you get novas (http://en.wikipedia.org/wiki/Nova ) which are essentially large thermonuclear explosions that happen on the surface of a white dwarf.

If a novae doesn't happen fast enough to expel accreted matter - then you get an Ia supernova.

And therefore your assertions about "when things go nova" cannot be talking about white dwarfs.

Wow,

Please, just type "nova" into Google and read the Wikipedia article. Let me quote a relevant passage: "A nova (plural novae) is a cataclysmic nuclear explosion in a white dwarf star. It is caused by the accretion of hydrogen on to the surface of the star, which ignites and starts nuclear fusion in a runaway manner. Novae are not to be confused with supernovae or luminous red novae."

And a white dwarf doesn't come before a nova.

So how can, when the subject is about what happens DURING a nova or supernova, white dwarfs be what you're talking about?

ESPECIALLY when you maintain that there would be nothing left there (i.e. after the event: NO WHITE DWARF).

I know what nova means.

I know what white dwarf means.

I know you're talking shite.

Maybe you need to read up on "Accreting Dwarf Binary" where a periodic variable can be caused by a white dwarf around a giant sun and where the accumulation of matter from the larger gas giant onto the surface of the white dwarf can lead to a nova event.

That is the only place where the white dwarf exists before the event.

However, that has even less chance of causing a complete destruction of the white dwarf because the white dwarf is already super condensed matter.

The ONLY possible way (apart from being torn up going in to a black hole) to disrupt a star to nothing is to do so BEFORE it becomes ultradense matter.

i.e. BEFORE it goes nova.

Even then I doubt extremely that it is actually even theoretically possible.

>That is the only place where the white dwarf exists before the event.

And in Ia supernovae: http://en.wikipedia.org/wiki/Supernova#Normal_Type_Ia

And yes, there's literally nothing left after the explosion. White dwarves have more than enough nuclear fuel to unbind themselves.

Yeah I was still concentrating on the version of reality that could possibly render a star's core nonexistent when it goes supernova.

But one that is an accretion supernova event is DEFINITELY NOT one of them.

The white dwarf is far far far FAR too dense to manage to be blown apart if it is heavy enough to retain the new envelope long enough to get a supernova.

A very small (and I'd be gobsmacked if it were even a 0.1 solar mass) white dwarf could become ripped apart if it were next to a supernova. But itself would not be able to retain the temperatures and pressures necessary to get a supernova event underway: the atmosphere would be blown off far far too early.

White dwars DO NOT have enough nuclear fuel to unbind themselves. It can't be ignited quickly enough and asymetrically.

It would be like trying to crush an egg by putting it in your hand and squeezing all the way around.

Not possible.

Wow.

You seem to have severe problems with reading comprehension. What dwarf becomes a supernova. The _whole_ white dwarf.

Explosion starts near the dwarf's barycenter and proceeds to destroy it completely. The dwarf's atmosphere probably doesn't even have enough time to engage in fusion before being blown apart by _neutrinos_.

No, you seem to have memory problems, Alex.

YOU claimed that the entire star could be ripped apart.

I said "Bollocks. Unless it's very small, but otherwise complete bullshit".

You seem to be segueing off to something completely different (and rather in line with the message Ethan gave at the top of the thread).

But a white dwarf ABLE to go supernova by accretion WILL NOT be ripped apart by going supernova.

A Brown Dwarf going supernova because of accretion MAY possibly be small enough to rip itself apart.

A white dwarf heavy enough to go supernova WILL NOT rip itself apart when it does. "the whole white dwarf going supernova" has feck all to do with that. It has to be heavy to GO supernova and if it is that heavy, it will NOT be able to be ripped apart by it going nova.

WILL NOT.

And what the fucking fuck are you blithering on about "blown apart by neutrinos" now????

You're going freaking nuts, mate.

Your cataclysm does NOT happen.

If the white dwarf doesn't undergo fusion IT DOESN'T GO SUPERNOVA (negating your idiotic "The _whole_ white dwarf" bollocks) because it would be merely the shell accreted going nova.

Your brains have exploded and dropped out your arse. Check your kecks for the bits.

I like this post, enjoyed this one regards for posting. "Good communication is as stimulating as black coffee and just as hard to sleep after." by Anne Morrow Lindbergh.

Wow, you're a moron.

Ethan, can you sort out this discussion?
Sanity check needed on the assertions.

Messier Monday: The Crab Nebula, M1

esiegel — Mon, 22 Oct 2012 15:31:52 +0000

Messier Monday: The Crab Nebula, M1

"This nebula had such a resemblance to a comet in its form and brightness that I endeavored to find others, so that astronomers would not confuse these same nebulae with comets just beginning to shine." -Charles Messier

Let's take a journey back in time to when our known Universe was a lot smaller. The only planets discovered were Mercury through Saturn: the naked eye planets. The well-known objects were our Moon, the (naked-eye) planets and their moons, and the stars and the Sun. After those, the only new objects that were routinely hunted in the night sky were those two-tailed recurring wonders: the comets!

Image credit: Loyd Overcash of DeerRidge Observatory, http://www.skyshooter.net/Comets.htm.

Other objects were known, such as novae and supernovae, but comet discovery was the primary goal of most astronomers of the day. In 1758, Charles Messier was no different, as he was eagerly anticipating the return of Halley's Comet, predicted by Halley himself to return in that year.

So you can imagine Messier's excitement when he looked through his large (for the time) telescope, and saw -- on September 12^th of that year -- something much like this.

Image credit: Chris Brankin's Deepsky (Messier) Objects, from http://www.stargazing.net/.

The bright star itself isn't interesting, but that nebulous blob above and to the left of it sure looked like the early stages of a brightening, returning comet to Messier! But, alas, this was no comet, as it neither brightened nor changed position nor altered in appearance over the subsequent nights.

Messier quickly realized that he was looking not at a comet, but at a much more permanent nebula in the night sky -- a faint, extended object -- that could be easily confused with a comet by someone who didn't know about its existence. And so began the Messier Catalog, a list of (eventually) 110 objects that would frustrate unsuspecting comet-hunters.

Image(s) credit: SEDS -- http://messier.seds.org/.

But each object in the catalog, containing not a single comet, has a remarkable story in its own right. Each Monday -- starting today, the first "Messier Monday" -- I'll be highlighting one of these Messier objects, visible through small telescopes (or binoculars) under good conditions, for you. (And we won't be going in order, so if you've got a favorite, let me know!)

To begin, here's how you find Messier 1, also known as the Crab Nebula.

Image credit: generated by me, using Stellarium, downloadable at http://stellarium.org/.

Tonight, if you step outside, the great constellation Orion should rise shortly after sunset. Many degrees above the top two stars -- Betelgeuse and Bellatrix -- but not quite as far as the very bright Alnath (or the planet Jupiter), you'll find a modestly bright star known as ζ Tauri, a 3rd magnitude star visible even within most cities on a clear night.

And if you point a good pair of binocular at ζ Tauri (under dark skies), here's what you're likely to see.

Image credit: Stellarium once again, configured by yours truly.

Among the bright stars, ranging from a deep orange to a bright blue in color, you'll find an unmistakably distended, faint, and fuzzy object. That's the Crab Nebula, or Messier 1.

Even in the hands of an amateur with an excellent quality telescope-and-camera, the level of detail that can be teased out of this object is breathtaking.

Image credit: Richie Jarvis; UK amateur astronomer and Flickr user.

What you're looking at is a star within our galaxy that died very recently: in 1054, to be precise! Since then, the supernova remnant has been expanding into the space surrounding it, creating the Messier object we know today as M1: the Crab Nebula.

And this spectacular object continues to evolve over time, as these two images -- from 1973 and 2000 -- demonstrate.

Image credit: © Adam Block / Mt. Lemmon Skycenter, combined with an older image from the Mayall 4m at Kitt Peak.

While the outer layers of this dead star continue to expand and cool, the inner core has collapsed into a pulsing, X-ray emitting neutron star, spectacularly visible to a space telescope like Chandra.

Image credit: NASA / CXC / MSFC / M.Weisskopf et al.

In fact, the pulsar -- spinning and pulsing some 30 times per second -- changes over time, as this seven-month timelapse video from the same Chandra team shows!

But, by far, the best view of this supernova remnant comes from the incomparable Hubble Space Telescope, which truly captures the detail of the expanding, filamentary structure from the outer layers of this dead star interacting with the interstellar medium.

Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University).

Although this image is an enhanced-color composite and mosaic (many images stitched together), the filamentary structure is real, as this detailed close-up illustrates.

Image credit: NASA, ESA, J. Hester and A. Loll (Arizona State University).

This supernova remnant may yet trigger the formation of new stars as it continues to expand and interact with molecular clouds, while the inner neutron star will continue to change over time, as its environment is far from being in equilibrium.

Don't believe that last part? Take a look at the Hubble close-up of the inner region, taken just months apart back in the 1990s, of the space around the pulsar itself!

Image credit: J. Hester and P. Scowan (ASU), NASA and HST.

This object -- the very first Messier object -- continues to evolve over time, and will achieve its 1,000-year anniversary, as best as we can tell, in July of 2054.

Enjoy the very first Messier Monday; it won't be your last!

esiegel Mon, 10/22/2012 - 11:31

Tags

I like this idea. I'll keep coming back for it.

Great idea. Nice post. One info is missing though: how far is it from us. I think that next time you should specify the distance.

Very nice post. Excellent way to start a new chapter in SWAB. The Hubble image is impressive, but the zoomed in image of the filaments is breath taking.

Question for Ethan. Pretend you've won a prize. As the winner of the prize, super advanced aliens will pick you up after work and take you instantaniously to the celestial destination of your choice, granting you superman powers to fly around and not die until you were ready to go home. What would you want to do/see if you could only pick one thing/location. You are constrained by time (no going back to just before the big bang b/c something tells me you would)

Can you give us some idea of the dynamics that leads to the filaments and the larger structures?

Great post . Love your work here - cheers

Nice article about the Crab. But one sentence is either a typo or makes no sense.

"Even in the hands of an amateur with an excellent quality telescope-and-camera, the level of detail that can be teased out of this object is breathtaking."

I mean... if it said "even... WITHOUT excellent...." then I could understand.
But if you HAVE excellent quality telescope and camera then you're not so much an amateur anymore, and it's normal that you'll get great detail.. that's why you have excellent quality :)

So in that sentence am not sure what you wanted to say :)

p.s.
The thought to have a weakly astronomy class on Messier objects... AWESOME!! :)) So looking forward to it.

UPS... sorry about the typo above... should be "weekly". :(

“Even in the hands of an amateur"

I think it makes sense as written. I would venture to suggest that a significant percentage of "excellent quality telescopes" are not only owned by amateurs, but spend many years confined to their basements once the novelty has worn off. A good telescope reflects more on the disposable income of its owner than on his skill in using it.

Part of the problem IMO is that you can get a scope and tripod for much cheaper than they are separately, but you get one that is only as good as the scope you have bought.

That means when you start off you have a cheap-ish scope and therefore a mount that only just manages it (e.g. a Skywatcher EQ2 and a 130mm Newtonian).

Problem is that if you like it and upgrade, you can't use that mount any more. So you have to buy a new one. Better would have been to buy one much better (EQ5 for example) because the mount lasts many telescopes.

That then makes you want to go for a more expensive scope so that it lasts longer.

And either you have too much to learn at once and get overwhelmed, find out that you don't really have the time or location or even inclination for this, or get on with it well enough.

Two chances to fail to use what you bought.

And although an SCT is a common starter scope, it is rather hard to get used to (especially if it is a GOTO) and still quite expensive. And hard to shift.

*singing* Just Another Messier Monday.

I know this is the first. Don't worry; I'll be recycling that comedic gold next week.

I'm pretty sure Ethan meant "amateur" in the literal sense of "unpaid", not the negative connotation of lacking skill. Making proper use of the good equipment requires skill. But both the equipment and the know-how is increasingly available to amateur astronomers. It's awesome because astronomy is one of those fields where enthusiastic amateurs can still make significant contributions.

Of course it *does* require a fair bit of disposable income. So yes, one could say that's the first thing possession of such equipment tells you about a person.

Personally I think the biggest problem is people trying to get into astronomy on their own, without a group, pretty much necessitating a GOTO scope to get any enjoyment out of it (for most people) and thus preventing the learning of important telescope-using skills. Fortunately I wasn't in that boat.

What you’re looking at is a star within our galaxy that died very recently: In 1054, to be precise!

Lucky for life on Earth it died several thousand years before it could be observed from our solar system in 1054. Oddly enough, the wiki link doesn’t appear to give the the actual date/distance.

We know the date on which it we first observed its death (which could be called 'when it happened' from our perspective, given special relativity and all) with far greater precision than we know it's distance. The wiki link does give the distance, and it's 6.5k +/- 1.6k light years.

It's nice to keep in mind that looking at distance objects is also looking back in time, but let's not try to be needlessly pedantic about it.

In the photo showing the difference between 1973 and 2000, I see some "stars" appear or disappear. Are these alien vessels, perhaps on their way here to demand Woody Woodpecker VHS tapes? I'm assuming yes, because I don't see any other explanation offered in this paragraph.

Donovan - re the first part of your comment
There is a difference in exposure/sensitivty between the two images. I would guess that some stars were too dim to see on the lesser exposure and 'appeared' due to the greater sensitivty of the later image.

As to the latter comments I have no idea what you are trying to say. Perhaps you could elucidate.

Donovan, there is at least one star (near top, right hand edge) which can't be explained by Shane's hypothesis as it varies too much. As M1 was seen as a possible comet, I would think it is quite close to the ecliptic, and that "star" is actually a planet.

I recall reading that the total energy output of the pulsar is around 100.000 times the luminosity of the sun, but the optical component is of course scattered by the nebula. So if this was a point source you would have a star at the distance of 6500 ly that was visible to the naked eye. Not bad.
--- --- --- --- --- ---
There are some supernovas that were never observed that have left a "light echo" in the interstellar medium, visible at the edge of sensitivity of the best telescopes. They not only show the approximate position of past supernovas, they also light up previously dark nebulas.

The crab nebula supernova was visible during the daytime.

That's how bright it was.

I am visible during the daytime, but that doesnt mean I'm bright.

You reflect the brightness around you, though.

Out in space, there's nothing to hear you gleam...

(you derserved that...)

I can't image what is more beautiful than space.

thatz beautiful

I will disappoint many people with this information, but the starting point of creating mythology of Jesus Christ served as a supernova M1 (Crab Nebula), which occurred May 11, 1184
. This is an astronomical phenomenon is reflected in the myth of
Phaeton. This period of our history can be considered and the date of the split
then the dominant religion in the three main branches.

Out in space, there’s nothing to hear you gleam

I understand a good number of 80s rock band members are bummed out because their music won't travel through space: there's nothing to make it glam.

thank you, thank you. don't forget to tip your waitress.

Well, it's kind of late now, but I've got another hypothesis to explain the difference in stars between the 1973 & 2000 images. It looks like vignetting to me. Notice that pretty much all the stars missing in the 1973 (purple) exposure are around the corners of the image. Thus, vignetting.
Another possibility would be variable stars, but I'd bet on camera/telescope limitations, i.e. the vignetting.

A Spectacular Chance for Gravitational Waves

esiegel — Tue, 21 Aug 2012 11:10:09 +0000

A Spectacular Chance for Gravitational Waves

"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov

One of the most spectacular and successful ideas of the 20^th Century was Einstein's General Relativity, or the idea that matter and energy determines the curvature of spacetime, and the curvature of spacetime in turn determines how gravitation works.

Image credit: Hyper-Mathematics - Uzayzaman / Spacetime.

From the orbits of planets to the bending of starlight, General Relativity governs all gravitational phenomena in the Universe, and accurately describes every observation we've ever made.

And the more concentrated energy is -- in any form -- in a given region of spacetime, the more severe the curvature that results. This means that if we can probe systems that are more extreme than we find in our own Solar System, we can potentially observe some aspects of General Relativity that are only theoretical predictions at this time.

Image credit: NASA.

While our Sun curves spacetime significantly enough to do things like bend starlight and cause a time-delay in communication signals, there are examples in the Universe that allow us to have a lot more fun with General Relativity.

Image credit: ESA and NASA.

In particular, white dwarfs -- like Sirius B, illustrated above -- condense a Sun's worth of mass into a volume of only the Earth, creating spacetime that's curved 100 times more severely than at our Sun's photosphere. One of the most extreme things that happens in our Universe is that we find multiple white dwarfs orbiting one another, creating a binary white dwarf system. (Binaries are very common; although our Sun isn't a binary system, our closest neighboring star is!)

According to General Relativity, these binary orbits are inherently unstable, and will eventually spiral in towards one another, coalescing, and eventually triggering a Type Ia supernova!

Image credit: NASA / Dana Berry, Sky Works Digital.

But objects that fall deeper into a gravitational potential well must somehow lose all that gravitational potential energy; where does it all go?

According to General Relativity, it gets radiated away, but not in the conventional form of radiation. Not in the form of known particles like photons and neutrinos; instead, this is a special type of radiation: gravitational radiation or gravitational waves.

Image credit: NASA.

Rippling through spacetime at the speed of light, these gravitational waves should be emitted each time a pair of masses orbits one another or each time a rotating object changes its shape. White dwarfs provide an increased curvature to spacetime compared to our Sun, but the most severely curved spacetime comes from neutron stars (which are a further factor of 1000 smaller than white dwarfs) and, in the most extreme case, black holes.

Thanks to long-term observations of a binary neutron star system, we even have indirect evidence for this orbital decay as predicted by general relativity; this discovery was so groundbreaking that it was worth a Nobel Prize.

Image credit: J.M. Weisberg, D.J. Nice, and J.H. Taylor.

All that's missing to complete the picture is a direct detection of this gravitational radiation. It's challenging, because a gravitational wave, when it passes through an object, only distorts its shape in this weird way, as the animation below shows.

Image credit: Markus Pössel of Einstein Online.

It appears to make a normal-shaped object first squished and fat, then normal again, then thin and stretched, then normal again, etc. Because all of spacetime is undergoing this, the object itself may have extraordinary difficulty noticing it, but there's no problem with seeing it for an outside observer.

Image credit: Auriga from the INFN in Italy.

On the other hand, this is happening in three-dimensional space, not in an idealized 2-D case, and they're coming from a source that is (probably) elliptical, rather than circular, in nature. So we have to take those things into account when we're looking for gravitational waves in reality.

Image credit: Markus Pössel of Einstein Online.

But the biggest problem with detecting them is that these gravitational waves are maddeningly weak. The amount of stretching/compressing that occurs in one direction relative to another is so small that, for even the Nobel-prizewinning binary pulsar, the number would be just 10^-26, meaning that a 1-meter object would stretch/compress by 10^-26 meters as a gravitational wave passed through.

So we fight this from two different angles: we look for sources that are even more powerful than the inspiraling neutron stars we talked about earlier, and we try to build detectors that are sensitive to the tiniest change in distance possible. The detector setup is known as an interferometer.

Image credit: LIGO/LSC, retrieved from albert.phys.uwm.edu.

Shine a monochromatic laser through a beam splitter, and send the two light beams off at 90 degrees to one another. This ensures that if a gravitational wave passes through, one "arm" will contract while the other expands, and vice versa. If the shift is sufficiently large, the interference pattern that shows up on the screen will shift in a predictable fashion, as dictated by General Relativity!

In practice, we have a few stations around the world that use this concept with two additions:

The entire apparatus is incredibly insulated from vibrations, motions, temperature variations, etc., here on Earth, and
They bounce the light back-and-forth along mirrors many times to artificially increase the path length.

Image credit: Ricky Geautreaux, Aero-Data Inc., Baton Rouge, LA.

This is what the LIGO collaboration/experiment, or Laser Interferometer Gravitational-Wave Observatory, is all about.

The difficulty is that it's only sensitive to signals stronger than about 10^-20, which is a very big number in this field, and it's only sensitive to very fast frequencies, or gravitational wave signals that repeat hundreds of times per second. The only astrophysical sources even capable in theory of being detected by LIGO are neutron star-neutron star mergers (not inspirals), neutron star-black hole mergers, black hole-black hole mergers, or a very fortuitous Type II (core-collapse) supernova.

Image credit: Amber Stuver of Living LIGO.

Unfortunately, this does not include the most common black hole mergers in the Universe: the ones occurring at the galactic center. They're so supermassive (and hence, their event horizons are so large) that they simply cannot be detected by the frequencies LIGO is sensitive to; the wavelength of the gravitational radiation will be too long for LIGO's "arms".

What makes this even more challenging is how close these (very rare) objects need to be to us in order to even have a shot at their gravitational waves. You see, the further away you are, the smaller the signal becomes. As always, we could get lucky.

Image credit: Dr. Christopher Burrows, ESA / STScI and NASA; Hubble Heritage team.

In 1987, the light from a Type II supernova that went off in the Large Magellanic Cloud reached Earth for the first time. It wasn't quite within our Milky Way, but it was close: just 168,000 light years (about 51 kpc) away. If LIGO was fully operational at the time, depending on the correct model for gravitational waves from Type II supernovae, it could have been detected.

Maybe.

Image credit: Harald Dimmelmeier, José A. Font, Ewald Müller, and Markus Rampp.

You have to get your amplitude up, at the proper frequency, into the detectable range. And it's difficult to know whether that's going to happen or not. After all, there are uncertainties here, and difficulties in modeling how something as complex as a supernova occurs!

Image credit: Davis Dulin of NC State, using an MHD simulation with genASiS.

Although supernovae are copious throughout the Universe, finding one within the 10 kpc (about 30,000 light years) normally used in simulations is an extremely rare occurrence, having happened maybe 9 times in recorded history, and only 2 of which were type II.

So rather than wait for the Universe to come to us, we can do something about it, and expand our sensitivity, which is exactly what LIGO's working on doing right now.

Image credit: H. Dimmelmeier, J. A. Font, & E. Müller (2002).

Expanding our search by upgrading to advanced LIGO should allow us to detect objects that are more than an order-of-magnitude farther away, while close by, we should be able to detect lower-amplitude objects.

One illustration of how the search expands from LIGO-in-its-current-form to the anticipated (2014) advanced LIGO is shown below, courtesy of David Shoemaker.

Image credit: David Shoemaker for the Advanced LIGO (LIGO II) Collaboration.

This may sound promising, but remember that our galaxy has had only 2 type II supernovae in the past 2000+ years, while the rate of binary mergers of collapsed objects is unknown but possibly far lower. Expanding our search range by a factor of between 10-to-maybe-50 (optimistically) could, conceivably, give us a few detections per year, but we could also see zero, and that wouldn't be surprising either. (Right, Clara, Sean, Nick?)

The fact of the matter is that LIGO isn't the ideal tool for the job of finding gravitational waves: LISA is, but we didn't fund it. Famous astrophysicist Kip Thorne may be predicting that LIGO will find gravitational waves by 2017, and this may happen, but it's unnecessarily optimistic. Advanced LIGO should come online in 2014, and assuming it reaches design sensitivity immediately (it took the first LIGO many years to get there), the event rates are on the high end of estimates, and the optimistic gravitational wave models are accurate, we'll definitely see multiple sources by 2017. Also, Kip Thorne will probably win a Nobel Prize; he'll be 77 in 2017.

But if even one of those assumptions is flawed, we have every reason to believe that gravitational waves still exist, and that Advanced LIGO won't see them. It's a spectacular chance for gravitational waves, but if we don't see them, it doesn't mean that relativity is wrong; it means we need to build a better tool for the job. I'm hoping this works as ideally planned, that it's working perfectly in 2014, and that we enter a new era of gravitational-wave astronomy. But if this isn't our entry, I'm not going to be surprised either, and neither should you.

The science is amazing enough without the sensationalism.

esiegel Tue, 08/21/2012 - 07:10

Tags

gravitational radiation

Where do Supermassive Black Holes Come From?

esiegel — Mon, 30 Jul 2012 19:55:17 +0000

Where do Supermassive Black Holes Come From?

"Black holes, which have no memory, are said to contain the earliest memories of the universe, and the most recent, too, while at the same time obliterating all memory by obliterating all its embodiments. Such paradoxes characterize these strange galactic monsters, for whom creation is destruction, death life, chaos order." -Robert Coover

Our Milky Way, the swath of light and dark that dominates the darkest skies here on Earth, contains a huge variety of stars: large and small, red and blue, from young to old to ancient.

Image credit: ESO / Serge Brunier, Frederic Tapissier, The World At Night.

But the very center of our galaxy contains, deep within its heart, one object that's unlike any other. Completely dark in the visible part of the light spectrum, due to the neutral gas and dust that prevent the light from getting through, we can successfully peer through to the center of the galaxy only in very specific wavelengths, and only from space.

When we do so, one region stands out from all the others, no matter how we look.

Images credit: NASA, ESA, SSC, CXC, and STScI; rectangles by me.

That bright region, outshining all the others in each wavelength? That's the innermost, supremely central region of the Milky Way. If we take our highest-resolution telescope, in the wavelengths most transparent to light, what do we find in this central region?

Image credit: Silas Laycock (CfA).

In short: a mess. Thousands upon thousands of stars crowded into a region of space that -- if it were of our local neighborhood instead -- would contain only our Sun.

Yet at one very small, special location, known as Sagittarius A*, an incredibly bright radio source lives among the young, hot, but otherwise relatively normal stars.

Image credit: ESO / R. Genzel et al. / Max-Planck-Institut fur Extraterrestrische Physik.

What's going on in that region marked by those two yellow arrows? The stars there are orbiting something with incredible speeds, something that, according to the known laws of gravity, is millions of times the mass of the Sun.

Image credit: KECK / UCLA Galactic Center Group / Andrea Ghez et al.

Oh, and also, it emits no light. That, my friends, is how we know we have a supermassive black hole at the center of our galaxy. It turns out that practically every galaxy has one, and the larger the galactic bulge, the larger the black hole at the center.

Composite image credit: X-ray - NASA, CXC, R.Kraft et al.; Radio - NSF, VLA, M.Hardcastle et al.; Optical - ESO, M.Rejkuba et al.

Most supermassive black holes are dormant -- or not active -- most of the time, and thus, like our own, are very difficult to detect. But looking deep into the Universe with the Chandra X-ray telescope, we were able to see a large number of active supermassive black holes.

Image credit: D. M. Alexander, F. E. Bauer, W. N. Brandt, et al., NASA and PSU.

When we extrapolate what we see here to the entire Universe, we find that about 300 million supermassive black holes are active and pointed at us at any given time.

That correlation of bulge-size to black hole mass is a good one, and there are only three known exceptions: one is when a merger kicks a black hole out of a galaxy, one is when a galaxy has some of its mass stripped away, as in the case of the galaxies below...

Image credit: X-ray: NASA/CXC/SAO/A.Bogdan et al; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF.

and perhaps most bizarrely, one is in the very early stages of the Universe, when the earliest supermassive black holes are more massive than you'd naïvely expect they would be. I was recently asked about this, and it is a very good question. So why do these supermassive black holes form, and why do they grow so massive so quickly?

After all, when we see supernovae, if they create a black hole at all, they only create a black hole that's a few times the mass of our Sun.

Image credit: R Jay Gabany of http://www.cosmotography.com/.

Maybe the largest supernovae we've ever seen created a black hole 20 or 30 times as massive as our Sun, but that hardly explains how we get up to millions or (in the largest cases) billions of solar-mass black holes.

To understand how this happens, I need to you imagine all the way back to the early stages of the Universe: before our Solar System existed, before large clusters of galaxies merged and formed, before generations of stars lived and died, before even the first clouds of gas and dust collapsed to form stars. Imagine back to when the Universe was relatively uniform, dark, and only beginning to have the most overdense regions begin to contract down, where they will eventually form the very first stars in the Universe.

Image credit: NASA / WMAP.

Eventually, the hydrogen and helium gases in the densest locations achieve high enough densities to ignite the first nuclear fusion reactions, causing stellar burning and star formation for the very first time. This is a Universe containing maybe 10²³ solar masses worth of hydrogen and helium, and the very first locations that are lucky to form stars will do it in chunks that range from many millions of solar masses down to may be as small as a few hundred thousand times the mass of our Sun.

Now, like all star-forming regions, there will be a huge variety of the types of stars that we form. Most of the stars will be long-lived, dim, low-mass stars, with progressively fewer of the heavier stars as we look to the more massive end of the spectrum.

But it is these most massive stars that are most interesting: the hottest, brightest, bluest and also shortest lived, these are the stars that will form heavy elements in their core (allowing for the eventual formation of planets), go supernova (enriching the Universe), and -- in certain cases -- collapse to form black holes.

Image credit: Nicolle Rager Fuller / NSF.

But it is the most extreme stars -- the ones that are over 130 times the mass of our Sun -- that are the most interesting as far as forming a supermassive black hole goes. Sure, less massive stars can form smaller black holes, but once you get above 130 masses, the interior of your star becomes so hot and energetic that the highest-energy radiation particles you create can form matter-antimatter pairs, which create an instability in the star that wind up blowing the entire thing into smithereens!

Image credit: NASA / CXC / M. Weiss.

Of course, this doesn't help you create a supermassive black hole at all, does it?

The thing is, this is only true for stars with masses above 130 solar masses and below 250 solar masses. If we get even more massive than that, we begin to create gamma rays that are so energetic that they cause photodisintegration, where these gamma rays cool down the interior of the star by blowing the heavy nuclei back apart into light (helium and hydrogen) elements.

In a star with more than 250 Solar Masses, it simply collapses entirely into a black hole. A 260 solar mass star would create a 260 solar mass black hole, a 1000 solar mass star would make a 1000 solar mass black hole, etc.

The question, of course, is do we actually make these, and do we make them in abundance that it's reasonable they would grow to form early supermassive black holes? To answer this, we turn to the largest star-forming region in our wimpy local group: the Tarantula Nebula located in the Large Magellanic Cloud.

Image credit: ESO / IDA / Danish 1.5 m / R. Gendler, C. C. Thöne, C. Féron, and J.-E. Ovaldsen.

This region of space is nearly 1000 light years across, with the massive star-forming region in the center -- R136 -- containing about 450,000 solar masses worth of new stars. This entire complex is active, forming new, massive stars.

It should be no surprise that our most recent, close supernova -- SN 1987a -- originated on the outskirts of the Tarantula nebula.

Image credit: the Hubble Heritage Team (AURA/STScI/NASA).

But it's not the outskirts, but the central, R136 region that is most spectacular. Let's dive right in to the hot, bright blue stars.

Image credit: NASA, ESA, & F. Paresce (INAF-IASF), R. O'Connell (U. Virginia), & the HST WFC3 Science Oversight Committee.

You may notice, right away, that there's one bright star that isn't blue at all, but rather red. This is an important star that may, in fact, become our night sky's next supernova.

Image credit: NASA, ESA, & F. Paresce, R. O'Connell, & the HST WFC3 S.O.C.

But this red giant, even if it forms a black hole, won't form a very massive one. Remember, we're on the lookout for stars with masses over 250 times the mass of our Sun.

The amazing thing is this: there is one in here!

Image credit: NASA, ESA, & F. Paresce, R. O'Connell, & the HST WFC3 S.O.C.

The most massive star known to humanity, R136a1, weighs in at 265 solar masses, and if its core gives out right now, it will collapse immediately to a black hole of 265 solar masses! This star, in particular, may not do that because of the heavy elements present, but in the early Universe, there are no heavy elements present, and so all stars above this mass threshold will simply get converted into black holes!

Because of how galaxies are thought to form in the early Universe -- by the rapid merger and accretion of collapsed, star-forming regions -- it's unthinkable that these early, large black holes wouldn't merge with one another and grow, forming increasingly larger and larger black holes at the centers of these objects: the Universe's first large galaxies.

Image credit: The National Astronomical Observatory of Japan.

If we can get just one 250 solar mass black hole for every 500,000 solar masses worth of stars, that means by time we get up to a Milky Way-sized galaxy, with maybe 2-400 billion solar masses worth of stars, we'd expect a central supermassive black hole of 100-200 million solar masses! This is exactly the type of growth we need to create the largest of the supermassive black holes we observe today, and we've got the evidence that the right type of stars form right in our own backyard.

So that's where the earliest supermassive black holes come from, and I hope you enjoyed your journey through time, space, stars and the elements: they brought you the Universe you get to have today!

esiegel Mon, 07/30/2012 - 15:55

Tags

In the picture with the three views (x-ray, near infrared, and infrared) there's another interesting region off on the left that's kind of box shaped. Any idea what that is? It's one of the few regions that also seems strong in all three.

Wow, I thought the supermassive black holes were just the first in the bunch, who got lucky to eat all neighbouring matter and grew to enourmous scales. I can't picture two black holes merging, what would it seems like?

That KECK-animated gif is too dodgy to be taken serious as proof for a Black Hole. Here is a video of how they found the spot:
http://www.youtube.com/watch?v=E-BM5_JyTeY

One picometer 'off-target' and 'our' view would have been blocked by some other star. Being able to capture this 'action' is almost the same chance as winning the lottery.

And the starts that seem to be twirling around that one spot, are just too vague to judge if they are in that specific area, and what their path is. This looks like a fraud ... emperor's new clothes.

The supermarket.

Easy.

The supermarket.

Easy.

The supermarket.

Easy.

Ethan - just let me thank you for doing such a GREAT job. Your content is comprehensive, accessible and sooo enlightening. I've been doing this astro thing for over 45 years and think myself relatively well informed (for an amateur), but you nearly always surprise me.

Hello Mr. Siegel! I have one question for you, if you don't mind. You said "Most supermassive black holes are dormant".... How can that be? How can a black hole not be active?

Thanks!
-Chelsea

Hmmm.

The site commenting system seems a little borken.

Post didn't appear. Tried under a fake ID to see if it were rate limiting, but that didn't appear either.

It looks like just this one.

That multipost wasn't me. The comment system is borked!

Chelsea- the difference between active & dormant is whether it's eating something or not. Our central black hole seems to have cleared the space immediately around it, so it's considered dormant. No ionized jets are visible. In other galaxies, we can see huge emissions from their cores, with spectacular jets shooting thousands of light years into space. I believe there were recent observations of one that indicated it had just eaten a whole star. Sorry I can't recall where it was, maybe Ethan knows?

Speaking of site problems, I push the Subscribe - RSS button at the top, but the reader says "no articles" and I never get any. It's been like that since the recent move. I'm running Safari over Lion on a MacBook Pro.

On topic, what might happen to these black holes as inflation accelerates? Will they rip apart?

@chelle: The "Keck animated video" Ethan posted is not an "artist's conception," and neither is some of the video you cited. They are both _real_data_!

The color coding indicates the signal intensity from the pixels of their CCD (the circles show you how much the point-like stars are smeared out when you look at them, which is called the "point spread function").

In your video, the boxed plot from 0:56 to 1:27 is exactly the same data, but shown in grey-scale rather than false color. Those are actual pictures of actual stars within ~3 lightyears of Sgr A*, not a cartoon.

We know that these stars are all orbiting a common point because we can _watch_ them, over the course of about a decade, and use that information to fit their orbital parameters. They are all following very nice Keplerian orbits around a central point, just like the planets, asteroids, and comets in our solar system.

Here are some links to papers with the actual research behind that very nice video you posted.

A good general review: http://arxiv.org/abs/1006.0064

The gas cloud G2, tidally disrupted and possibly on a capture orbit: http://arxiv.org/abs/1112.3264, http://arxiv.org/abs/1201.1414, http://arxiv.org/abs/1207.4215

The close-in star S2: http://arxiv.org/abs/0910.3069

You can find a lot of really good papers on different aspects of Sgr A*, including discussions of near future _direct_ observations of the central SMBH, by searching arXiv for "Sgr A" in quotes, http://arxiv.org/find/all/1/all:+EXACT+Sgr_A/0/1/0/all/0/1

Michael,

I'm not saying that this animated gif nor the video is an 'artist’s conception' they are real alright. I only question the claims of it being stars circulating da black hole in the center of our Milky Way. Like I said the chance of being able to look at precisely THIS area is about one in a million. Haven't you seen how the detection of this spot is a continuous zooming-in between thousands of other stars, ... just a tiny fraction to the side and we would be able to see it. Could we really be this lucky, is what I ask myself. Second the imagery is so vague that with some ingenious visual enhancements you can make it look as if they're all in that confinement of space, it makes me think of an illusion done by David Copperfield. And yes the papers are very nice, it is only that the visual proof doesn't look sufficient enough. Maybe I've been fooled too many times (once) in my life that I have become too skeptical about things that look too good to be true. If you like to take this as valid proof, than that you are entitled to do so, but I'm not very convinced. Also I'd like to see what is there to see in a section next to this one and compare, and if all around that particular spot there is nothing going on well than you might have convinced me, but not this early in the game.

One more thing, I also would like to compare it to an N-body simulation and the gravity interaction of a few stars closely packed together and given a group rotational velocity without a 'black hole' near it. It might produce the same type of stellar dance.

OMG, RSS has been fixed ALREADY! Thanks, whoever...

Dr. Siegel -- I wish to thank you for writing these wonderful explanations of the universe. You know how to hold my attention. Thank you, Robert Buckley

Well.that answered my question about the center of the galaxy.

Chelle, the mass of the object orbiting is given by the valocity of the stars orbiting. The size is given by the shape of the orbit.

The density resulting csnnot be reasonably be explained by stellar objects.

Additionally, the brightness of a suitable cluster central mass if stellar in origin (remember stephan's law) would be readily discernable.

Stars don't cut it.

Wow, I'm not going to argue about the fact if there is or isn't a Black-Hole in the center of our Milky Way or any other galaxy. We've already had a lot of debating regarding this point and I respect your opinion.

I'm only focusing here on the 'proof' of that KECK-gif and YouTube-video. Look at it again as of 0:55

I have cut that part out and transformed it into a .gif-file:
http://www.freeimagehosting.net/newuploads/kqjiu.gif (1.4 Mb)

Look how the timeline goes up from 2004 up to 2011, and back down to 2002. This creates the illusion that those stars are making some Kepler loops. Yes, they have put the years next to it, but along with some soothing music and some extra more impressive visuals, you are in a way misleading spectators and creating an illusion, covering up the weakness of the proof.

Maybe the YouTube material is very vague due to uploading, but transforming it into the 'precise' KECK-gif-animation that Ethan presents here on the blog, seems to be a too presumptuous leap to me. All this along with the one in a million chance of capturing it, leaves me with no other option than to conclude that it is probably a fraud.

Well why don't you go and simulate the N-body problem blah blah blah and answer your question?

@Chelle

what are saying man? You think that youtube video is a proof for black holes??? That's just a nicely presented summary of piles and piles of data and analasys bundled down to 1:50 mins or so...

You say that couple of images don't proove it. ANd they don't. But you're the only one who seems to think that's all there is to it. Did you even bother looking at the papers mr. Kelsey linked to you? My bet is you didn't. And you were even arogant enough to dismiss them with a slight of a hand. Saying: "And yes the papers are very nice, it is only that the visual proof doesn’t look sufficient enough."

Go and read those papers, and if you still disagree, put valid questions and doubts about the methodology with specific issues if you can, instead of bashing some ppl for making a cool animation based on data.

What the hell do you want anyways?

> "why don’t you go and simulate the N-body problem

http://en.wikipedia.org/wiki/N-body_problem

Sinisa,

Check this article:
http://www.nature.com/nature/journal/v455/n7209/full/nature07245.html

It clearly states that Sgr A* is located off-center from the suggested supermassive black hole that would be at the center of our galaxy. The 'proof' from KECK appears to be no good.

> "What the hell do you want anyways?"

I do like to be entertained when I go see a movie or a have a laugh with my friends, but when it comes to science I prefer the truth.

@Chelle

"It clearly states that Sgr A* is located off-center from the suggested supermassive black hole that would be at the center of our galaxy. The ‘proof’ from KECK appears to be no good."

mmmm... NO!

You either missread the paper that you linked just now, or you do not understand what they are saying.

Quote from the paper you linked: "...suggesting that the bulk of Sgr A* emission may not be centred on the black hole, but arises in the surrounding accretion flow."

Read it for what it is, and not what you want it to be.
They are saying that the majority of x-ray emissions seem to be coming from the accretion flow and not the center itself. Accretion flow of the BLACK HOLE.

"You either missread the paper that you linked just now, or you do not understand what they are saying."

It's a common problem for chelle.

"Read it for what it is, and not what you want it to be."

Hasn't happened yet.

chelle, why don’t you go and simulate the N-body problem?

you averred you have done it:

"I also would like to compare it to an N-body simulation and the gravity interaction of a few stars closely packed together and given a group rotational velocity without a ‘black hole’ near it. It might produce the same type of stellar dance"

SL, I think Chelle wants science to be wrong.

Just that.

"SL, I think Chelle wants science to be wrong."

Even more than that he wants himself to be right, with aliens, crop circles, worldwide scientific conspiracy, CERN destroying the universe, black hole fraud and the whole nine yards... Oh yes, and little quantum organisms swimming in eather.

Sinisa,

Here is the link to that paper itself:
http://arxiv.org/pdf/0809.2442v1.pdf

It says:

"A long-standing astronomical goal is to resolve structures in the innermost accretion flow surrounding Sgr A* where strong gravitational fields will distort the appearance of radiation emitted near the black hole ...
This is less than the expected apparent size of the event horizon of the presumed black hole, suggesting that the bulk of SgrA* emission may not be not centered on the black hole, but arises in the surrounding accretion flow."

And now let's look at that KECK-simulation that zooms straight in to where the radio source of the Black Hole is, and guess what, 'BINGO!' The Milky Way's Black-Hole is just right in front of our eyes with looping stars around it and even a 'flare', well the best thing is that we got it on tape. And gee, wow, that is a one in a million shot ... it must have been our lucky day! Well this is the stuff for 'true believers' like you and Wow, but not for me, sorry.

> "Oh yes, and little quantum organisms swimming in eather."

Ha ha, yes, I'm still busy with it, here's a little teaser:
http://youtu.be/CTqaiMpcOJg

p.s. Ethan I hope you don't mind this little off-topic plug, if Sinisa hadn't mentioned it ...

SL, I think that these "theories" of chelle are really just mechanisms to achieve the goal: "Science is wrong".

Wow,

That is a good observation. Indeed I'm trying tho prove that some theories of Science are wrong and that there are fraudulent illusions being used, and all this by using the Scientific method.

"Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge."
http://en.wikipedia.org/wiki/Scientific_method

"Indeed I’m trying tho prove that some theories of Science are wrong and that there are fraudulent illusions being used,"

ok, good luck with that. So basically you're saying Ethan and the rest of the community are frauds spreading disinformation.

So what in the world are you doing here?

Try integrating the knowledge that is new to you, rather than rejecting it all the time so that you can continue to peddle idiotic pseudoscience.

> "So what in the world are you doing here?"

First of all I'm here because Ethan's posts are presented in the most fun way, there is always a story to them, and they go straight to the heart. And it is not because I don't agree with all the material that he brings up, that I'm anti-science. Science is a far too broad field, to classify criticism about one subject as an attack on Science. In fact scientific research is about 99% failure and 1% success, and now I'm even being to optimistic, but that is the truth.

Second, I visit this place because I like to participate in the debate, but I also want to keep an honest view. And if I think that the LHC is a hazardous thing, than I will say so, even if it is the bread and butter for a lot of scientists who depend on it, physics is not sociology; and if I find this KECK-sim a fraud than I will also speak my mind; and I will also defend a possible NEW Aether because it is a super interesting concept with lots of possibilities. This is what science is about, sharing ideas and impressions, it is not only about listen & learn (integrating the knowledge that is new to you). Sinisa for a big part I see you doing the same thing; asking questions all the time, and sharing opinions. Perhaps I have an eye for some more global aspects, and not so much one for the more specified details that you are very good at. We all have different views, so it is imho best to keep an open mind.

Chelle,
Your point seems to be that its unexplainable or low-probability that we should be able to see this phenomenon. That it is suspiciosuly easy to do.

But Ethan's comments after the second picture describe just how difficult it is. We can only observe it using a few, specific, wavelenghts. Which are way outside the visible range. And which require space-based telescopes.

So I can't see what your issue is. Yes, there IS lots of stuff in the way. Yes, this stuff DOES block our view of it. Ethan says that very clearly - intervening gas and dust make it invisible in normal wavelengths. You are exactly right - it WOULD be suspicious if we had a clear visual shot of it. But you are wrong in implying that we have such a shot. We don't. Astronomers need exacting and unusual instruments to observe it precisely because we don't have a clear shot at it.

Its like arguing: isn't it suspicious how we can just see individual atoms with scanning tunneling microscopes? What are the odds that the instrument's capability exactly matches the size and properties of an atom? Answer: no, and 100%. Those instruments took a lot of time and effort to build, and they are designed precisely to overcome all the detection problems we have seeing individual atoms. There is nothing suspicious, easy, or suspiciously easy about it.

Eric,

> "it WOULD be suspicious if we had a clear visual shot of it."

Exactly, if you look at my first comment, the overall 3rd one in this thread, than you'll notice that I only question here the KECK-gif, that is intended to be 'a clear visual shot of it', and there is also this animation:
http://www.youtube.com/watch?v=E-BM5_JyTeY

You can argue about what a 'visual' shot is, as these 'images' are generated by captured radio-waves, but if I understand correctly, than those signals can also be simply blocked by a single star. Our Sun for example has a diameter of 1.4 million kilometers, so how could a radio telescope, even one that is a few kilometers wide, ever look at a very large area beyond one single star when it stands in its way, … and there are thousands of stars in that area that can 'visually' block the suggested Black-Hole in the center of our Milky Way. So yes with radio-waves we can look further through clouds of gas and dust, but not through other stars that block our vision. Anyway, to be able to capture what's going on at the exact spot of the grand BH of our Galaxy seems to me one hell of a lucky shot.

Excellent explanation Ethan!!

Chelle freely admits, "I’m anti-science... scientific research is about 99% failure and 1% success."

But even in this statement, Chelle misrepresents himself. He implies that he is only against the 99% of scientific research that ends in the dustbins of science history.

But Chelle is anti-science because he is against the 1% of science that is a success, i.e. that is supported by thousands (even millions) of observations.

wikipedia "Direct Doppler measures of water masers surrounding the nuclei of nearby galaxies have revealed a very fast Keplerian motion, only possible with a high concentration of matter in the center. Currently, the only known objects that can pack enough matter in such a small space are black holes."

My point is that 100s of failed explanations were tried; but the only 1 that worked, the successful explanation is that the "Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System, in a region called Sagittarius A." This is an example of the less than 1% of scientific research explanations that is correct (i.e. is in agreement with the thousands and millions of observations and data).

Our Sun for example has a diameter of 1.4 million kilometers, so how could a radio telescope, even one that is a few kilometers wide, ever look at a very large area beyond one single star when it stands in its way

Because (1) no stellar objects "stand" in our way, they move fairly rapidly across our field. Because (2) you are thinking of the signal origin as a point source 'hidden' behind a sun, when in fact the signal source is much much bigger than any stellar object that would move between it and us. To be 'bigger' than the sourse, it would have to be much closer to us, but the density of stars drops precipitously outside of the core. And because (3) stellar objects do not simply block light, they bend it, acting in some ways like a lens.

Though I think in this particular case, (3) is largely irrelevant because of the distances, distributions of stars, and speeds involved. You are essentially wondering how a GPS signal can reach my transponder with all the potential gnats in the way.

"You are essentially wondering how a GPS signal can reach my transponder with all the potential gnats in the way."

Lol, I have no problem accepting that there is a strong signal in the middle of our Galaxy that we can receive, but what I do question is the KECK-gif and that YouTube video, that claim to show some gnat circulating around the signal source, behind all the gnat that's flying in-front of it.

btw regarding that strong signal, I wonder if it couldn't be something like the mechanism that causes Brownian motion, an accumulation of small signals that acts as one big punch, as the center is surrounded by a wall of stars and dust, a lot of signals could be bouncing around, just like a guitar body that works like an amplifier :)

Chelle, a galaxy is far larger than 14 million km across. Our sun isn't bigger than a galaxy.

Wow, fill a page with hunderds of dots. Now try to draw a straight line from the outside towards the exact center without passing one dot. Now increase the situation to 200 billion, because that is the amount of stars in our Milky Way, and try to do the same thing, because we are on the outskirts of the spiral Galaxy, and the strong radio signal is in the middle. Keep in mind that every dot has a diameter of about a million km. See how difficult it is to get a peek at what's going on right in the middle. Of course you can pick up the big signal, but to hit 'bulls eye' is a case of extreme luck, it isn't just one Star that you have avoid, but columns and columns of randomly distributed stars, it all adds up, line after line, increasing at each step the chance of getting your view blocked. And it is not like looking further into deep space that can widen out, here everything gets to be more compact the further you look. That's why I find those claims highly suspicious.

"fill a page with hunderds of dots. Now try to draw a straight line from the outside towards the exact center without passing one dot. Keep in mind that every dot has a diameter of about a million km"

Don't forget the relative scale of things. Compared to the interstellar distances, 10^6 km would be an essentially infinitesimal size. There is so much space between the dots that it would be difficult for one to actually get the way.

Chelle,

Remember, the universe is very very old and very very big so extremely unlikely events happen a lot more frequently than your able to wrap you human brain around. The universe doesnt care what you think should and shouldn't be. The piles and piles of data/observations lead us to the best possible explination. I don't get whats so hard to accept. You have been given several excellent reasons why stars and dust dont block the view. Whats the hang up?

The hang up is that, for chelle, the science cannot be right.

Ergo the explanations on how its right cannot be correct.

Close binary systems are hundreds of millions of km apart.

Or less than 1/100th the size of the star.

That are CLOSE BINARY separations.

The 4 light year separation between us and the nearest star is not unusual, however, which is 80000 times further.

Lol, I have no problem accepting that there is a strong signal in the middle of our Galaxy that we can receive, but what I do question is the KECK-gif and that YouTube video, that claim to show some gnat circulating around the signal source, behind all the gnat that’s flying in-front of it.

Your example shows why your intuition is wrong. We see gnats behind gnats all the time, because they don't move together. Relatively different movement makes it easy to subtract foreground objects to get the background.

And again, like Jasso in that I think your intuitions about object density are all wrong. As a more astronomically relevant metaphor, does the asteroid belt doesn't occlude our view of Jupiter? No.

[In fact, getting object densities in space wrong is a very typical sci-fi gaffe. Movies show ships having to dodge and weave to avoid getting hit. In real belts, the asteroids are so distantly spaced that you'd need a telescope to see one object from another.]

There's a lot of gas and dust in the way, but Real galactic densities are much lower than you

err... there's an extra "doesn't" in there and that last line should finish with "expect."

"The orbits of stars within the central 1.0 X 1.0 arcseconds of our Galaxy. In the background, the central portion of a diffraction-limited image taken in 2010 is displayed. While every star in this image has been seen to move over the past 15 years, estimates of orbital parameters are only possible for the seven stars that have had significant curvature detected. The annual average positions for these seven stars are plotted as colored dots, which have increasing color saturation with time. Also plotted are the best fitting simultaneous orbital solutions. These orbits provide the best evidence yet for a supermassive black hole, which has a mass of 4 million times the mass of the Sun. " http://www.astro.ucla.edu/~ghezgroup/gc/pictures/orbitsOverImage10.shtml

"Stellar orbits at the Galactic center proving the existence of a black hole. The star S0-2 dominates our knowledge about the central potential, since with an orbital period of 16 years it has been tracked throughout a whole orbit. The other stars have longer orbital periods and therefore only a fraction of their orbits is covered by observations... With care, the planned astrometric and spectroscopic adaptive optics observations for Ro, along with measurements of other short-period stars, should enable measurements of stellar orbits with sufﬁcient precision to detect non-Keplerian effects due to General Relativity (GR) and extended dark mass. The leading order effects are the special relativistic transverse Doppler shift and the gravitational redshift. These effects should be observable when S0-2 goes through its next closest approach in 2018 thereby marking a test of Einstein’s equivalence principle... A detection of GR effects in the orbital motions of the short-period stars at the Galactic enter would probe an unexplored regime of GR, which is the least tested of the four fundamental forces of nature" http://arxiv.org/pdf/1207.6755v1.pdf

So not only to we have 15+ years of orbital data. from which the composite images and videos sammarize. That astronomy research program aimed at the center of our Milky Way galaxy is precise enough that by 2018; it will have collected enough data to " test of Einstein’s equivalence principle" and "unexplored regime of General Relativity".

This is very nice, spectacularlly persistent, precise and excellent astronomy research of the highest calibre. Absolutely amazing.

Chelle chooses to NOT question the pretty good working hypothesis of how supermassive black holes are formed; in which there is room for discussion about various details of the excellent explanation that Ethan gives..

Chelle chooses to question the most precise astronomical measurements imaginable; he question observational research data that had been carefully, precisely gather for 2 decades and will continue in with even more precision and diligence for next decade.

Chelle chooses to argue against the most successful of the 1% of science successes; i.e. the most precise observations, verified by the best telescopes around the world and in space (Hubble) in an international research program that has spanned 20 years.

This is why Chelle is anti-science; because he attacks the very best science;
as he promotes psuedoscience analogies "Brownian motion.. one big punch... a guitar body that works like an amplifier"

And NEVER, does Chelle stop and refelect and say, "I did not know that. that is amazing science." Chelle learn something and bring something important/relevant to the science discussion.

OKThen,

Oh yeah, sure I am an Anti-scientist, no problemo :mrgreen:

Jasso, Wow, crd2 and Eric,

I have been talking about chance and until a certain point it is clear that we are lucky to peek straight into the heart of our Milky Way, and yes this is for al large part to due because of the scale of things. Nonetheless, there could have been some star in the way blocking our view. Anyway, for winning the lottery you need to have all the numbers correct, of lets say a ticket with 8 digits. Now let's compare this to our situation, and I agree that we have clearly all the first seven digits correct, because until a certain point we have a clear view at the heart of the Milky Way. Now comes the question do we also have the 8th and last number correct? It is here that I would like to take a look at the information that we have. I made an overview for ya'll:
http://m.UploadEdit.com/bat/1343919122764.jpg

As you can see in the first image (A) with all the 'Normal Stars' that Ethan originally posted here on the blog, you can see that we have a clear entrance towards 'the center'. The next question now is, what is the center and how do we now that it IS the center? Here it is the Complex Radio Source 'Sagittarius A' that shows us the way, that you can see in (B), and a close-up (C) with the location of the proposed Black Hole 'Sgr A*'.

To now look through all the clouds of dust we use the images from the Keck Observatory, made with the Observatory Adaptive Optics (AO) systems and its Laser Guide Star (LGS). It gives us the Central 4"x4" image (D), and it is full of Stars. And we can look more closely at 1"x1" (E) where we start noticing a lot of movement and 7 stars that follow the Kepler Ellipses (F). All the way at the right, we there's a 0.5" x0.5" image (G), that shows all the details.

What I find strange when looking at these pictures, is that our supposedly giant Black Hole Sgr A* is located in a dark bay-area 'off-shore' from where all the red-action is (C), but than again that dark bay is full of Stars (D), and they're all moving around just like we can see in the KECK-gif that is presented here. What I would like to know is if there are no other Kepler type of motions going in on in that large Bay-area, instead of only that particular spot, and what IS actually going on in the red-hot land section?

Next, let's have a look at picture (F); there we can see in the upper-left corner a very large bright object, perhaps one Star or a group of stars, but it is a rather significant body, very close to Sgr A*, and it makes me think that a lot of that Central Core of our Milky Way (Sagittarius A), might be full of that kind of objects that could be visually blocking parts of the core, as it would be the case when we would move a picometer ‘off-target’ in our first image (A), or in image (D)... there is even the question of how deep we have to zoom-in (???) because some Wikipedia says that: "The exact distance from the Sun to the Galactic Center is notoriously uncertain.

All this makes me question if we have indeed got our 8th and final number correct, and got to be very lucky; or if we got just very close and have picked something that looked as funky as a Black Hole, but that may in fact be some n-body celestial interaction of which there could be many more in the center of our Milky Way.

"and until a certain point it is clear that we are lucky to peek straight into the heart of our Milky Way"

You mean that certain point of actually thinking about whether it's a lucky happenstance or a pretty normal occurrence?

"Nonetheless, there could have been some star in the way blocking our view."

How likely is that?

> How likely is that?

True. You can indeed also pose the question; how lucky one could be to find a star in it's way, it works in both ways. I would say pretty lucky once you enter that central parsec, look at that 4"x4" it is still packed full with Stars, and that region isn't even in the zone where the strongest radio noise comes from.

Radio-wise it also seems to be rather problematic to tell what the actual center is, because beyond a certain point the center is just there, and finding that one particular Black Hole looks like finding a needle in a haystack. There doesn't seem to be a clear signal, what I would expect from a Super Black Hole that is roughly 100.000 solar masses, it mainly is that big radio cloud.

I hve posed the question. You, however are presuming an answer.

You don't get to 'say it both ways' because you are claiming incredulity based on a specific answer.

If you cannot show it unlikely to be clear of obstruction, you must withdraw the claim.

You know it's pointless arguing with someone who reverse-engineers their way from the answer to the evidence using analogies and unexamined gut feelings, right? They'll either eventually wake up and realize how logic and reasoning work (or at least consider it worth while to find out), or they'll continue to fill up the internet with drivel, spurred on by the attention.

But hey, I'm not telling anyone how to spend their time. If it's what amuses you that's cool. If not... successful troll is successful.

CB,

That's a true story.

Anyway It looks like I've found the missing link in the 'reverse-engineer' process:
http://www.astro.utu.fi/~cflynn/galdyn/GalCntr_lg.gif

This red-island fits, with some twisting and turning, into the bay-area of that 'Complex Radio Source' image, and has a clear dot it the middle, and looks like a bit the eye of a hurricane.

@eric
I loved your typo:
"Real galactic densities are much lower than you"
A rather good assessment of chelle's density.

I would expect from a Super Black Hole that is roughly 100.000 solar masses, it mainly is that big radio cloud.

On what do you base your expectation? Did you do a calculation that disagrees with published measurements?

Look, maybe its best that you just stop using metaphors and analogies altogether (to be fair, I will too), because they seem to be leading you to wrong conclusions. Just re-look at Ethan's 5th picture. The center is very crowded, yes, but it seems pretty clear that we can resolve individual objects in this region.

What is your alternative hypothesis for this? Do you think astronomers are doctoring their images? Do you think its not a black hole? Its gravitational and spectral properties don't seem to match anything else. What do you think image 5 is really showing, if not what Ethan says it is?

Eric,

My problem is that I'm skeptical about the existence of Black Holes as a singularity, because I personally guessed that as a singularity it would stick out more in space, due to the proposed Hawking Radiation, I find it also strange that one type would continuous suck up energy and such. Therefor I was skeptical about finding such a Black Hole, and I always thought of the origin of a Galaxy as something that is similar to the mechanics of a Hurricane; a matter of the Thermo Dynamics in the DM & DE / Aether and plasma and dust clouds, along with the forces of gravity, therefor I imagined that the core of a galaxy would be like the eye of a tornado, with lots of particles twirling and spinning around. So when I saw that animated gif I thought it would have been nothing else but a shot of one of the many the solar bodies that are vastly around moving in and around the center. Also the Black Hole / Galaxy Center seems have the 'weight' of the amount of stars that makes up a galaxy, in an n-body situation that might level out I suppose, and gravity would be the most intense in the core. For example in the case of a F4 tornado here on earth, there is an equivalent energy input of 100+ Tsar Bombs concentrated in such a vortex, while in the eye it is calm.
But now it looks in the images exactly like the eye of a hurricane in a giant storm, just a single dot in a closed off section that differs from the next area around it, spiraling out etc.

Seeing how those 7 stars rotate around that central point, still leaves the door open for a non-singular object also because the orbits don't seem to fit perfect. Although I can accept the physical correctness of a Galaxy with a super massive BH in the center. I'm just wondering of the current path of Science just checking if my intuition makes sense or not.

Nonetheless no one can't deny that is quite amazing to be able to see and capture the exact motion of those stars at in the center, we have been lucky.

"because I personally guessed that as a singularity it would stick out more in space, due to the proposed Hawking Radiation"

You will need to read up on what Hawking Radiation is first:

http://en.wikipedia.org/wiki/Hawking_radiation

cliff notes version: you're doing it wrong.

Forget the nonsense that certain folks CHOOSE to spout to deliberately obfuscate, misinform, etc.. all with purpose to discredit science. Of course such anti-scientist "are constantly at work to invent so-called alternative theories and craft legislation.. to require.. to teach unscientific notions." Daniel J. Fairbanks pg 7.

But such anti-science pugalists do science the great service of forcing scientist communicate science more clearly. e.g. Daniel J. Fairbanks excellent, astonishing new book Evolving (The Human Effect And Why It Matters) 2012 is science writing at its best. http://www.goodreads.com/book/show/14289169-evolving

Science today precisely deals with the seemingly seemingly impossible experiments and observations.

"Particle physics uses a standard of "5 sigma" for the declaration of a discovery. At five-sigma there is only one chance in nearly two million that the result is wrong, i.e. the measurement seen is a random fluctuation."

"In October 2006, the X Prize Foundation, working in collaboration with the J. Craig Venter Science Foundation, established the Archon X Prize for Genomics,[47] intending to award US$10 million to "the first Team that can build a device and use it to sequence 100 human genomes within 10 days or less, with an accuracy of no more than one error in every 1,000,000 bases sequenced, with sequences accurately covering at least 98% of the genome, and at a recurring cost of no more than US$1,000 per genome."... In June 2009, Illumina announced that they were launching their own Personal Full Genome Sequencing Service at a depth of 30× for US$48,000 per genome... Jay Flatley, Illumina's President and CEO, stated that "during the next five years, perhaps markedly sooner," the price point for full genome sequencing will fall from US$48,000 to under US$1,000... In May 2011, Illumina lowered its Full Genome Sequencing service to US$5,000 per human genome, or US$4,000 if ordering 50 or more."

From genomics to particle physics to astronomy; observations and experiments are being done with mind-boggling precision. And that incredible precision is the standard process of production in research, medicine and engineering.

"Six Sigma became well known after Jack Welch made it a central focus of his business strategy at General Electric in 1995, and today it is widely used in many sectors of industry... A six sigma process is one in which 99.99966% of the products manufactured are statistically expected to be free of defects (3.4 defects per million). Motorola set a goal of "six sigma" for all of its manufacturing operations, and this goal became a byword for the management and engineering practices used to achieve it."

Get use to it!

Chelle, your last post is so filled with bs that I can't help but reply. Over and over again you claim you're here to learn and preach scientific methods and what science is suppose to be, yet your last post obviously marks you as total opposite.

"I’m skeptical about the existence of Black Holes as a singularity,"
- lie... they needn't be singularities at all. Just need to have enough gravitational pull to not allow even EM radiation to escape. This very thing was a topic of one of Ethan's posts a while back. And you even read and commented on that post. So don't put singularities here as excuse.

"I personally guessed that as a singularity it would stick out more in space, due to the proposed Hawking Radiation"
- lie... with this sentence you clearly show you haven't got even a basic notion of what Hawking radiation is.

"Therefor I was skeptical about finding such a Black Hole"
-lie...after more than a year on this blog you haven't learned a single thing. Why is that is beyond me. Your notion of BH is non-existant since you lack the knowledge of even the fundamental notions of physics of BH's. "such" a black hole as you think of them are only in your head. Not science, but your haphazard daydreams.

"I always thought of the origin of a Galaxy as something that is similar to the mechanics of a Hurricane;"
- that's your problem and your own lack of knowledge. Not the problem of people here or physics in general. God knows you had plenty of opportunity to learn, you chose not to.

"a matter of the Thermo Dynamics in the DM & DE / Aether and plasma and dust clouds,"
- there is so much bs in this sentence that I won't even comment it. Perhpas this sentance is the best representation of your total persona. Let's mix and mash some fancy sounding words that might seem related to cutting age science and some kid might think I'm cool. Not a scientist but a total sharlatan and fraud.

"I imagined that the core of a galaxy would be like the eye of a tornado,"
- yes.. you imagined. Physics and this blog don't deal with unicorns, lepricons, hobbits, crop circles and imagined things. They deal with scientific concepts and experiments. You are the only one putting up fictional bs where it doesn't belong. I love sci-fi and epic fantasy, but I don't write about that here, nor do others.

"in an n-body situation that might level out I suppose"
- lie... you haven't got the faintest idea of what would happen, you just desperately want to sound like you know what you're talking about. You're not fooling anyone here.

"Seeing how those 7 stars rotate around that central point, still leaves the door open for a non-singular object"
- again bs. Seeing what? singularity or non singularity has nothing to do with rotation of stars. You've just shown all of us here you don't even know how gravity works.

"also because the orbits don’t seem to fit perfect"
-lie.. you would so wish to sound educated and important. Fit what? Perfect? What would the perfect orbit be?

"Although I can accept the physical correctness of a Galaxy with a super massive BH in the center"
-lie... you don't know enough physics to accept to decline anything dealing with cosmology. You've shown that in previous sentances

"I’m just wondering of the current path of Science"
- the sooner you leave it be, the better of Science will be. God forbid we ever get "scientist" like you.

"just checking if my intuition makes sense or not."
- it doesn't

"we have been lucky"
- guess what brainiac, luck has nothing to do with it. A lot of hard work by a great number of dedicated and professional people made all that possible. Without them we wouldn't see anything. This isn't lottery.

“I’m skeptical about the existence of Black Holes as a singularity,”
- lie… they needn’t be singularities at all. Just need to have enough gravitational pull to not allow even EM radiation to escape. This very thing was a topic of one of Ethan’s posts a while back. And you even read and commented on that post. So don’t put singularities here as excuse.

You might be right although it says on the wiki-page:

Since the central singularity is so far away from the horizon, a hypothetical astronaut traveling towards the black hole center would not experience significant tidal force until very deep into the black hole. - http://en.wikipedia.org/wiki/Supermassive_black_hole

And the singularity HAS NOTHING TO DO WITH HAWKING RADIATION YOU BLITHERING BUFFOON.

It isn't visible because its buried in the event horizon.

"the singularity ... It isn’t visible because its buried in the event horizon."

That's an interesting point. I would have thought that it was 'beyond' the event horizon. Arrr, bring me that horizon so I can check it out: http://youtu.be/CMZCK7dsmc0 (0:50)

What do you think the difference is?

> "What do you think the difference is?"

In the case of something like a hurricane, the wall that makes up the eye in the middle, would also be the event horizon, and this ring-wall would indeed be where the massive object is.

If it would be something like a single massive object, like a star, than the event horizon would surround that object and thus the 'singularity' would beyond it.

The difference is, that the former is the result of a 'whole' lot of action and energy going around making up that event horizon wall, while the latter is considered to be an object by itself, a singularity.

Can't see how te hurricane analogises. Where's this singularity analogy?

"Can’t see how te hurricane analogises. Where’s this singularity analogy?"

Exactly.

Exactly none?

OK. There wasn't a point, then.

And you didn't answer what the difference was, did you. Just went off on one of your signature idiot tangents.

Ethan,

Really great article, a fast and easy read, fantastic photos, especially the animation and the Tarantula nebula shots, well done. I look forward to many more.

Thank You,
Mike

Wow,

I did answer your question, my point was, that there is no point that causes the attraction in the case of a hurricane, versus the singularity that is a massive object. It is a group mechanism versus an individual object (Black Hole). Just like how pulling the plug in you bath creates a whirlpool, there is only an opening, not an object, and a lot of pressure of the whole of the water in your bath, the speed of the stuff that gets to be swung around, is the cause of a global mechanism, not that of a singularity.

There is a REPULSION in a hurricane centre. Gravity, the operating force in a black hole is ATTRACTIVE.

Therefore the two are not analogous.

Despite that, you did not answer the question which was what is the difference between buried inside an beyond the event horizon.

PS do you know anything about how a hurricane (or indeed any low depression cyclonic storm)?

..forms.

(Oopsie, clicked send too early)

There is a REPULSION in a hurricane centre. Gravity, the operating force in a black hole is ATTRACTIVE.

Here is an image showing what's going on:

http://tinyurl.com/hurricane-mechanics

There is NO repulsion in the hurricane center, and like I've now said plenty of times, the hurricane has no massive point in the center (singularity), so there is nothing beyond or inside the event horizon. The wall that makes up the eye of the hurricane, is the event horizon, that is the difference.

Read up on centrifugal forces, kid.

The geostrophic equation gas a term for that in there which puts a limit on the depth of a depression.

The centrifugal force has got nothing to do with, do you never take a bath, If so than you would notice that the drag of the whirlpool of the water, energy flowing out, sucking everything along with it there is no repulsion. What do you think the DM & DE Fluid is doing there, just hanging tight?

Regarding the 'geostrophic equation' look at that radio image of the center of the Milky Way and compare it to this temperature image of an hurricane's eye:

http://www.nasa.gov/centers/goddard/images/content/135564main_goes_ir_l…

It was this radio image that I was referring to:
http://www.astro.utu.fi/~cflynn/galdyn/GalCntr_lg.gif

"The centrifugal force has got nothing to do with, do you never take a bath"

You missed out a middle to that sentence.

And the bath plughole would need to be fifty miles across for cyclonic flow to cause the spinning we see in synoptic systems (which is what you're alluding to, because you are getting Coriolis forces mixed up with centrifugal ones).

You are as clueless about the hurricanes you so obsess over and see everywhere as you are about just about everything else.

"Regarding the ‘geostrophic equation’ look at that radio image of the center of the Milky Way"

Bugger me.

You really are even more clueless than I believed possible in a mobile human being.

Several problems here, all in a single tiny package.

1) There is no friction, pressure or lamelar flow in a galaxy, therefore you cannot apply the geostrophic equations.

2) If you look at the water going down a plughole, you'll see rotation just like the low pressure systems, but caused by a different mechanism.

3) That picture also looks like a cowpat. However, nobody is pretending that the Great Green Arkleseizure is doing a jobbie on the universe here.

4) Look at the centre of a non-spiral-arm galaxy. E.g. M81. You're looking for a pattern you WANT to see. And, unsuprisingly, you're able to find the pattern. Your idiocy is in thinking that just because you can find a pattern you understand what's causing it.

"There is no friction, pressure or lamelar flow in a galaxy"

Are you braindead?

No. Just because you're an idiot and don't like it, doesn't mean that the answer to anyone correcting you is "are you braindead?".

Chelle
Here's the deal.
There is a difference in arguing to win your case regardless the absurdity of your case (i.e. like a defense lawyer); and using your best arguments to learn and understand (i.e. like a scientist).

You argue like a defense attorney not a scientist.

So for example, when Wow explains, "There is a REPULSION in a hurricane centre. Gravity, the operating force in a black hole is ATTRACTIVE." The appropriate learning response should be, "Oh, I did not know." By the way I did not know. What I do know is that when Wow explains the science; he explains it correctly.

The you Chelle say, "Here is an image showing what’s going on: http://tinyurl.com/hurricane-mechanics There is NO repulsion in the hurricane center"

But have you looked at the very image that you show us. Look at the arrows in your image moving upward (red arrows) and outward (blue arrows). That outward is the repulsion that Wow describes.

There is nothing scientifically wrong with saying, "Oh, I did not know." Of course a defense attorney wants to win his argument regardless of reasonableness. But a scientist will throw out his best idea when it conflicts with observation (i.e. the various velocities measurements of the speed and direction of wind from the eye of a hurricane outward.)

Now a defense attorney will argue with such meteorologic data; but a scientist would rather be wrong and learn.

thus I thank Wow for explaining hurricanes better; I really haven't thought about them much. But if we are going to have good gneral relativity sense about something like a black hole; then we need to have a good classical mechanical sense about something like a hurricane. And understand how they are different, very different phenomenon.

So we each get to decide if we will be or not be scientifically minded. Being lawyerly minded regarding scientific things is to be a psuedoscientific, or anti-scientific.

Well, correctly enough for words.

To be correctly correct, you need the maths.

But the results of the maths can be REALLY weird. E.g. evanescent waves. Or the Lamb Shift. Heck, even the proof of why cyclones go anticlockwise in the northern hemisphere is kind of weird without the maths (or three pairs of double-jointed hands...).

A Hurricane is caused by the divergence of upper air wind. This causes the lower pressure in the centre (since there's less air there, there's less mass in the air column, therefore lower pressure).

The surrounding air is pulled in by the pressure gradient, along the isobaric pressure lines.

This causes rotation on a synoptic scale in accordance with the coriolis force.

However, the air is going IN and therefore describing a smaller and smaller circle around the low pressure zone, which means that it is turning a tighter and tighter circle. Which means the centrifugal force counters the pressure force inward.

These two forces balance out and you get a maximum pressure drop for a low pressure system and in the more extreme case of a hurricane, a calm area where the air cannot manage to get in because the incoming air is forced out by the centrifuge effect.

And therefore the air spirals up, the centre of the storm is somewhat self-sustaining and as long as enough energy is coming in to keep it going, the hurricane will survive a long time.

Upper air divergence occurs when something like the jet stream turns north, where the momentum change causes the air to slow. So we get a lot of temperate zone low pressure zones

See

https://www4.uwsp.edu/geo/faculty/ritter/geog101/textbook/weather_syste…

for a picture.

@OKThen,

"There is NO repulsion in the hurricane center”

But have you looked at the very image that you show us. Look at the arrows in your image moving upward (red arrows) and outward (blue arrows). That outward is the repulsion that Wow describes."

Come on, you can do better than that. Of course there is stuff flying out of the center, but not in the middle (centrifugal force) and that was what Wow was talking about.

Anyway here is an image of Gamma Ray jet's flying out and the bubbles that are formed: http://tinyurl.com/GAMMA-RAY-BUBBLES

p.s. if you find my style of discussing pseudoscientific anti-scientism than so be it, I don't care, what are you going to do, burn the witch?!

@Wow,

Yes that's a nice synopsis, and I agree with the fact that; "you need the maths". But something like a hurricane is a very complex organically evolving structure, you can calculate the forces but the whole mechanics of it is an interplay of many different factors. Similarly the mechanics of a Spiral Galaxy is something very complex and there is the questions of what the Dark Matter is doing towards the center, does it gradually changes 'temperature', are there flows, does the density changes, like you explain about a hurricane's center "... it is turning a tighter and tighter circle", what about such a more compact area of DM that interacts gravity-wise ... look how much empty space there is between those stars and how much more matter there could be compressed like foam, you could be talking about perhaps 10^x times more matter per cube, and you quickly come to the conclusion that a Black Hole (singularity) is the easiest answer ... and If you say that it is, than I will respect your opinion because mathematically it might work, but maybe in reality a Supermassive BH is more something of a process than an actual object.

The center of a hurricane is an eye; the center of a black hole is a singularity.

Hurricanes, bathtubs and toilet bowls do not have event horizons; despite Chelle's private definition "The wall that makes up the eye of the hurricane, is the event horizon."

We try to educate witches; and point out that witch people (e.g. like Chelle) generally add confusion to scientific discussion by parading private psuedoscience definitions, e.g. "center of hurricanes" and "event horizons of hurricanes".

What do you think pressure is, if not repulsion, chelle?

Are you here to get beaten up? Is that how you get your kicks? Because you're not even pretending to think any more.

OKThen & Wow,

I made my point, if you don't like than so be it.

Have fun!

What was the point?

You're clueless? Unloved? A troll?

Yes, I am a clueless unloved troll. :mrgreen:

Have fun!

I see the comments have turned from discussing the data and the models to personal attacks.
I’ll add my bit.
The Ghez papers discuss the data and suggests there are over a million suns size mass within 40 AU (use to be 60 AU) of the focus of the stars she tracked. What is the distribution of this mass? There were calculations (Richstone I think) that suggested that if Newtonian mechanics with gravity applied, then countering the self gravity would require a rotation velocity great enough to fling all the mass out. (I see the hurricane analogy but the mass is much greater than the analogy could allow.) Since this has not happened, the conclusion is there is some other force unmodeled by standard physics at work OR the mass would self gravitate to a supermassive black hole. There is some data that suggest it is not a supermassive black hole such as the periodic X-ray bursts (radiation in the X-ray band without accompanying radiation in other bands) and the apparent quiet nature of the mass (call a sleeping black hole in some papers). Here we have the problem.
I’m sure the scientists who would like to be funded wish the inconsistencies would just go away.
Certainly, all science models are wrong as if that is any news. Of course, current models will be replaced. Current models do explain considerable amount of data. Like General Relativity corresponded to Newtonian mechanics in limited circumstances, so the new model (currently called the “Theory of Everything”) should build on current models.