astro
catdynamics | January 26, 2009wherein you can learn about the "No Teleportation Theorem" and why there is no classical Scattering Theorem
or some such nonsense...
me, podcast with bonus video feed.
Argh.
one of the nice, but occasionally disturbing things about the Kavli Institute of Theoretical Physics is that they podcast and video essentially all their talks,
including
this one, with the soporifiic droning of yours truly
this is very, very disturbing...
there is also an audio podcast, not that I'd recommend having this on your iPod on long drives.
catdynamics | January 23, 2009it is still raining?!
so we have an east coaster telling us about actual data
on x-ray binaries
in clusters, globular clusters
in other galaxies...
there is an open-to-the-program-members blog over on the cluster09 wikispace.
It has some good summary of yesterdays in depth discussion on runaway mergers in the afternoon session.
Chandra image of NGC4697
so our pivot point is the issue of low mass x-ray binaries (LMXBs) - mass transfer binaries, with compact primary, generally a neutron star, and a companion with a mass lower than some vague mass that is either about a solar mass, or…
catdynamics | January 23, 2009Carnival of Space #87
yes, it is carnival time again - the science carnivals have been fading recently, good to see something is still going
catdynamics | January 22, 2009it is raining, might as well liveblog the morning session...
runaway mergers of colliding stars - the quick and dirty intro...
stars are, in fact extended bodies.
This is mostly irrelevant to astronomers, since typical stellar separations are very large.
But, in dense stellar clusters, the density of stars can be a billion times higher than in the field - and hence separations thousand times smaller - and then the finite size can be really important.
Especially if stars also happen to be in binaries, but that is a different story...
So... to make a long story short, sometimes stars go "…
catdynamics | January 21, 2009Multiple stellar populations in globular clusters (overview).
like this in NGC2808 (paper)
or even good old M4, and and NGC1851, and of course Omega Cen.
the original view of globular clusters is that they are the quintessential coeval sets of stellar populations - that all the stars in any given cluster ought to have formed more or less simultaneously, with an age spread of no more than a few million years or so
but, now that we have very good colour-magnitude data from wide field Hubble images, with proper-motion selected field decontamination, it turns out that many, maybe most,…
catdynamics | January 21, 2009Change is good, right?
Nice of Sean to take the blame, just in case someone is feeling curmudgeonly about it.
Not that they should, since the option of continuing the old way by default is still there...
That is change we can live with.
catdynamics | January 20, 2009getting organized
- unlike the totally laid back string theorists, the astrophysics program has daily morning meetings to discuss progress
except today
today we get to meet after lunch, everybody was kinda busy this morning for some reason...
then we get informal short talk presentations once a week on thursdays, on top of the seminars, colloquia and lunch talks - the thursday talks will be recorded and podcast and video feeds made available online
ooh, first monday seminar will be:
""Emergent phenomena in negative heat capacity systems: fundamental physics from dense star clusters"
by, er…
catdynamics | January 20, 2009New calculations suggest the question of whether the universe is holographic or not is testable, and recent data is consistent with the model, and consistent with the universe actually being holographic.
h/t Jake at Pure Pedantry
Prof Craig Hogan, the new director of the Center for Particle Astrophysics at Fermilab, has written a series of very interesting papers suggesting that space-time quantization at the Planck scale ought to show up as white noise in the transverse displacement of laser interferometers, with a power spectrum that is just √(tp/2), independent of frequency, given some…
catdynamics | January 15, 2009D
we set D equal to the measured value from A.N. Experimenter et al (2009)
we set D = 8π3/2/3 (Stokes 1854)
we set D = 8π3/2(1 + ε)/3, where ε = 4.2*10-7 is the Me-Stokes parameter (Me 1973), correcting for second order effects.
do you mean a total derivative or a partial derivative?
well, the "D"s cancel, so we can approximate it as just δy/δx ~ y/x...
if you choose D=2 we can get an exact solution
consider the qualitative behaviour of the solution as we vary the number of dimensions
you mean ℘?
(curse html 4.0 and its lack of proper symbols...)
Ð!
catdynamics | January 15, 2009I am currently at the Kavli Institute for Theoretical Physics, hanging out at the "Formation and Evolution of Globular Clusters" workshop.
Apparently I am, for now, also the official "program blogger" program rapporteur...
cause you know everything sounds fancier in french
Who knew.
When David suggests something is a good idea, it becomes a good idea.
So, right now I am kinda busy trying to keep up with the workshop - there are some interesting new things, which I'll get to in due time. Real Soon Now.
Y'all can participate through the multimedia online presence, including video (live and…
catdynamics | January 14, 2009Hubble supplemental decisions are done, e-mails are coming out this morning.
Score!
bloomin' heck.
Now what do we do...?
So, how did y'all do?
Hold on.
Phase II is due when?
(Jan 27 in case you wondered, that is less than 2 weeks)
Aargh.
catdynamics | January 6, 2009random snippets from the 213th semi-annual meeting of the American Astronomical Society in Long Beach
not that I am there...
Hannah - one of the co-bloggers at Women in Astronomy is liveblogging from the AAS
I hear there were some excellent talks and posters on black holes and galaxies and white dwarfs and stuff...
the Universe Today crowd are doing a good job covering the meeting
if you want to read just one snippet, the allegedly recoiling supermassive black hole is a good one
catdynamics | January 5, 2009not only am I missing the 213th (semi)annual meeting of the American Astronomical Society for the second year in a row, due to external extenuating circumstances, but I am managing to do so while actually in southern california, near where the meeting is...
bummer
Anyway, there's a bunch of bloggers down there chewing through the press releases and doing multimedia casts, check out:
Universe Today
Astro Engine
Star Stryder
US Node of International Year of Astronomy, 2009
actually looks like the Universe Today affiliates own this one, not even Phil P. made it to the meeting
if you're a…
catdynamics | December 31, 2008The Spiral Star.
Pretty.
Pretty Funky.
What is this?
Well, it is AFGL3068, aka Carbon Star L3068, aka IRAS 23166_1655, one of the poster images for the "Asymmetrical Planetary Nebula IV" meeting last year.
Soon, hopefully, to be an observing target of the Advanced Camera for Surveys on the Hubble Space Telescope, if Servicing Mission 4 ever takes place, and ACS is actually fixed, and Cycle 17 gets underway.
It is kinda funky.
Tempting to think of a binary companion explanation, but I am curiously prone to think of a binary companion as an explanation for most anything...
Here's the paper…
catdynamics | December 29, 2008The Sun undergoes quasi-periodic cycles of 22 years, which manifest most observably as 11 year sunspot cycles.
There have been 23 of these 11 year cycles in recorded history, going back to about 1750.
NOAA has a good summary.
The pre-historic cycles are done through reconstruction, and there is evidence for century scale variations superposed on the regular cycle, notably the multi-decade Maunder Minimum.
We just went through solar minumum, and cycle 24 is underway.
But, the current level of activity remains quite low.
It is not in the worryingly anomalous range yet - not like we can say we'…
catdynamics | December 18, 2008The Near-Infrared Camera and Multi-Objects Spectrograph on the Hubble has been resuscitated.
Damn, that means those 50 odd supplemental proposals are in the running as well as the almost three hundred WFPC2 proposals already in the queue...
"As of 1:20pm EST Tuesday 16 December 2008, the compressor on
the NICMOS Cooling System / NICMOS Cryo-cooler (NICMOS
NCS/NCC) was restarted and the system has since started
cooling successfully, with NICMOS expected to be operational
in a few weeks from now."
They let the pump warm to 10C, the blockage must indeed have been water ice and it is gone - cold…
catdynamics | December 11, 2008The next decadal survey of astronomy and astrophysics has been formed and the panel is about start meetings and townhalls.
Astronomy has a tradition of decadal surveys of research priorities, which have been enormously successful.
The surveys are a National Research Council run activity under the Board on Physics and Astronomy and the Space Studies Board, and is supported by NASA and heavily relied on by NASA Science Missions Directorate for guidance on big mission priorities.
A new survey is urgently needed, given our rather interesting times, and likely changes in directions and priorities…
catdynamics | December 11, 2008As you know, Bob, the Large Hadron Collider broke, after it was turned on and demonstrated to function, but before any full design energy collisions took place.
Before the LHC there was the SSC which also met its demise in strange ways.
Coincidence?
I think not...
Now these are large, complex, expensive machines.
As such they are subject to political whims, and engineering flaws.
But, some of the smartest people on Earth have teamed up to get together the resources and build and operate these supercolliders, to probe physics at the highest energies. And they've always worked before.
On the…