Posted by “They credited us with the birth of that sort of heavy metal thing. Well, if that’s the case, there should be an immediate abortion.” -Ginger Baker
As hard as it may be to believe, take a look outside. I don’t mean a glance, I mean to take a real look. At all the things there are to see — the rocks, trees, mountains, skies, clouds, Sun, water, and everything alive — all of it.
Image credit: Fir0002/Flagstaffotos, under the GFDL.
Now ask yourself, “what’s it made of?”
At a fundamental level — like everything else you know of — everything on Earth is made of atoms. Oxygen, Hydrogen, Carbon, Nitrogen, Calcium, Iron, Gold, etc., all the elements of the Universe combine together in a huge variety of ways to create everything we know of an observe in the Universe. When we peer inside of them, we can find the very thing that gives each and ever atom its special properties.
Image credit: 2011 CrystalMaker Software Ltd.
Unbelievably, it’s simply the number of protons in each atom’s nucleus. And this huge variety of things that we have in our world only comes about because of the huge variety and abundance of these elements, from Hydrogen to Uranium and beyond.
Image taken (and modified) from Kyle Pounds' Powers of Ten page.
But these elements haven’t always been around. And they certainly haven’t been around for all that long in the abundances they’re found in today.
In fact, just a few minutes after the big bang, the Universe has cooled to low enough temperatures that it’s done undergoing all the nuclear reactions it can possibly undergo. And at that point, we can take a look at what all the elements in the Universe are.
Image credit: James Schombert at University of Oregon.
Perhaps surprisingly, the Universe is made up of (by mass) about 76% Hydrogen, 24% Helium, and less than 0.0000001% of everything else, combined. The Universe has no problem cooling and forming neutral atoms after this, but with just Hydrogen, Helium, and minuscule, trace amounts of everything else, you’ve got to wonder at what we have today.
Image credit: NASA/ESA, Russian Federal Space Agency, Maxim Suraeva and Oleg Kotov.
In other words, where does all this come from?
How we made all the elements we have today is the same way we’re making them right now: in stars.
Image credit: NASA/JPL-Caltech/L. Allen and the IRAC GTO Team.
Our Sun, like the vast majority of stars, is fusing hydrogen into helium, and that’s what’s powering it. But the heaviest, most massive stars burn through their fuel far more quickly.
And once they burn through their hydrogen, they fuse that helium into carbon, and then into nitrogen, oxygen, neon, and sodium, and then into silicon and sulfur, and then into iron, nickel, cobalt and copper.
Image credit: Demetris Nicolaides.
The ones that make it this far are anywhere from eight times the mass of our Sun up to hundreds of times as massive. While our Sun takes somewhere in excess of ten billion years to burn through all of its fuel, these more massive stars take anywhere from tens of millions of years down to just tens of thousands of years before they exhaust the fuel in their core! And then, what happens next is simply spectacular.
The star in question goes supernova, where enough energy is released to form all the elements in the Universe, and to form them in great abundance.
And, as you can see in the video above, these elements are released out into the Universe. If you’re a hydrogen/helium “purist”, you might say that they pollute the Universe. But if you’re all in favor of these heavy metals and elements throughout space — like me — you’d say that they enrich the Universe.
In some regions, where you had lots of high-mass stars in the past — particularly if you’ve had multiple generations of stars — you’d expect that you’d wind up with plenty of metals. Perhaps, in fact, that’s the picture you have in your head when you think about our Sun. After all, when we take a look at our Sun, we see an incredible number of spectral absorption lines, surefire indications of heavy elements!
Image credit: N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF.
Unlike the “pristine” Universe, our solar neighborhood is enriched, with about 2% of all the elements found in it heavier than hydrogen or helium. Our Sun has been through at least two previous generations of stars that have formed, burned their fuel, died, and enriched their region of space. But it is by no means one of the most enriched regions of the Universe, or even of our own galaxy.
Where do we look for that?
Image credit: NASA, ESA and Michael West (ESO).
It’s the centers of the most massive galaxies — the brightest, most active, violent regions known in the Universe — that possess the greatest abundances of elements heavier than helium, collectively known as metals.
Galaxies can form stars just 50-100 million years after the Big Bang in our Universe, and can go through not just one or two but many generations — in the most massive, rich galaxies — before we ever see the light from them.
Which is why every time I see a report like this (or this):
In a surprising find, scientists have detected carbon much earlier in the Universe’s history than previously thought,
I’m completely baffled. Because unless they mean “in the 1920s” when they say “previously,” that’s not what we think at all!
Image credit: NASA/STScI/NAOJ.
This is TN J0924-2201, the most distant radio galaxy ever discovered. (At a redshift, z, of 5.19. For redshifts, higher numbers mean the Universe was younger and the object is farther away.) And this is the scientific paper that was written about it. But is this a surprise that there are so many heavy metals in this galaxy? Let’s quote from the article itself:
there is no redshift evolution of… metallicity in the redshift range of 2.0 < z < 4.5. Using near-infrared spectroscopic observations… Jiang et al. (2007) found no strong evolution of… metallicity up to z ∼ 6. Recently, Juarez et al. (2009)… found that the metallicity is very high even in quasars at z ∼ 6. These results indicate that the major epoch of chemical evolution in AGNs is at z > 6.
So don’t be fooled; the Universe is well-known to be rich, full-of-metals, and highly evolved just a few hundred million years after the Big Bang, or when it’s only 5% of its current age!
For example, take a look at this “baby” galaxy.
Image credit: NASA, ESA / JPL-Caltech / B. Mobasher.
This galaxy, a mere 700 million years old, is so redshifted that even the light coming from it — most of which is blue and ultraviolet in color — has been shifted out of the visible part of the spectrum! Yet this galaxy is not only eight times the mass of the Milky Way, but is even richer in these heavy elements than our Sun is!
And yet, we know that — at some point in the past — the truly first stars formed, made up only of hydrogen and helium. Well, where did that happen? Our only choice is to keep looking back.
Image Credit: NASA, ESA, G. Illingworth, R. Bouwens, and the HUDF09 Team.
This is the current record-holder for most distant galaxy ever: UDFj-39546284, from when the Universe was only 480 million years old, or 3.5% of its current age!
This galaxy is a small collection of hot, blue stars, with not even 1% of the mass of the Milky Way! Is this where we were forming the first stars? Or is this galaxy even typical of the galaxies that are out there at this early stage in the Universe?
Our best theories tell us that we wouldn’t be surprised if galaxies as far back as this one were abundant, rich in metals, and — in many cases — of comparable masses to our own Milky Way, already. But at some point, some distant galaxy was first. And we want to know where that was, and when that was.
At this point in time, there’s only one plan in the works to find that out.
Image credit: NASA.
Add just one more reason to the list of why we need the James Webb Space Telescope!
So until we get there, don’t be surprised that the distant Universe is full of heavy metals, evolved stars, or massive galaxies. The Universe is a place where everything we know can not only happen, it happens fast. It does make you wonder, though, just how long ago — under the right conditions — planets, and even life, could have formed!
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