maggiekb at February 11th, 2014 10:54 — #1
nathanrudy at February 11th, 2014 12:33 — #2
I wonder what the night sky would look like if we could even up the amount of time the light had taken to travel. Some of the starlight has traveled 10 years to get here, some 50 million, some more. But it all arrives at the same time.
I wonder if anyone could render a picture of only the light that was sent our way 100 million years ago, so all stars younger than that would be eliminated. How much would be missing?
jeremysmyth at February 11th, 2014 12:48 — #3
If stars shine through fusion, making heavier atoms from lighter ones, surely a star of any age tends to having heavier atoms over time rather than lighter. I don't understand the science in this story. Can someone explain how such an old star can have so few heavy atoms in its spectrum?
chenille at February 11th, 2014 12:57 — #4
Little stars last the longest but only fuse hydrogen up to helium, so don't really produce heavier elements. Those are formed in the later stages of larger stars - and to simplify some, even there you tend not to see so much, since the layers aren't mixed as well and so the heaviest elements remain around the core while it lasts.
Combining the two, when you see lots of truly heavier atoms in the atmosphere of a star, you can conclude they were mostly already in the mix of gases that it formed from. So a star with none is one that ought to have formed before such elements started being released.
miasm at February 11th, 2014 13:02 — #5
I haven't even finished the article yet and my jaw is already on the floor.
Just 6000 light years away
Ok, so it's not light from ages ago at the edge of the visible universe. It is only 6000 light years away and isn't moving near the speed of light through the galaxy. It is not composed of heavy metallic elements but is noted as being a second generation star, not too cold, 0.8 solar masses...
It can't be that old.
My money is on some kind of new star forming mechanism which somehow strips out metal or light elements to form a star... I mean, what the hell has it been burning otherwise?
chenille at February 11th, 2014 13:46 — #6
Stars even a little smaller than the sun are expected to last a lot longer. That's partly because the brightness falls off quickly, but also because in the sun only the outer layers are cool enough to convect, so only the hydrogen around the core is available to sustain fusion. As stars get smaller, though, more and more of the gas is mixed together and so available as fuel. I think models give a 0.8 solar mass star as lasting maybe 20 billion years; a 0.2 solar mass star should last trillions.
So actually, a question about population III stars is why there aren't lots of them still floating around. An explanation I had heard is that they probably only formed much larger; elements like carbon act like catalysts for hydrogen fusion, so before them proto-stars maybe took longer to ignite and thus tended to accumulate more mass first.
hannesalfven at February 11th, 2014 13:58 — #7
Relative to other "hard" sciences, cosmology and astrophysics are actually incredibly speculative endeavors. Note that Air & Space Magazine is currently running an article on the "Dark Flow" and "Cold Spot" observed in the most recent attempts to observe the CMB, and the very existence of these claimed anisotropies casts doubt upon the entire big bang theory.
So, just realize that while we continue to talk about the inferred timeline for these stars, that that very timeline is itself still something which is being contested. After all, if we are observing large-scale anisotropies in the CMB -- as appears to now be the case -- then that calls into question whether or not the CMB is indeed originating from the edge of space. The simplest explanation for large-scale anisotropies is that the microwave emissions are in fact locally generated.
We'd be wise to use far more cautious language than has become customary within science reporting today. After all, radio astronomer Gerrit Verschuur has claimed to have observed many dozens of correlations between the WMAP hotspots (which are supposed to originate at the "edge" of the universe) and local hydrogen emissions associated with kinks in interstellar filaments of (HI) hydrogen.
In response to these claims, the WMAP team ran some automated algorithms which they claim failed to show Verschuur's correlations. But, for those who actually read Verschuur's papers and books, he is very clear that he could never have come to his results with automated algorithms. There is a very simple reason for this: These frequencies are important to us largely because they pass through dust grains. So, what we see is numerous signals on top of one another, all originating at different locations in the universe. In order to sort these different signals out, a human must be involved in the processing. It takes Verschuur many thousands of hours of hand-processing to come up with his correlations.
So, when the WMAP team runs an algorithm and tells the world that there is nothing to see here, people should realize that this is a bit like shaking one of those 8-balls until you get the answer you expected.
tachin1 at February 11th, 2014 14:52 — #8
You mean like this?
O yeah, and the article actually contains the following "we don’t actually know the star’s age… quoting any age is pretty much made up."
awjt at February 11th, 2014 15:07 — #9
But there's got to be something about gravity too. Whatever came before these small, slow-burners had to have exploded in such a way that any heavier elements were separated out into those stars, and masses of nearly pure hydrogen went thataway over into these stars. There must have been some form of a fractionalization of materials. Maybe not gravity; just using that as an example of what I mean.
miasm at February 11th, 2014 15:11 — #10
yah, I like the idea that SETI should be focusing on Red Dwarfs with tidally locked inner planets.
seems like there might be some contention on the mass of the star...
anthonyc at February 11th, 2014 15:27 — #12
I blame starlifting type II civilizations.
glitch at February 11th, 2014 15:49 — #13
To find a star which is so devoid of metals, it must be old. Very old. Old as balls.
chenille at February 11th, 2014 16:23 — #14
I'm not really sure what you mean. Stars do end up with a bit different compositions, but the separation between the main populations is by time.
The idea is that things started with mainly hydrogen and helium, and then the amount of heavier elements scattered in our galaxy gradually went up as dying stars released them. So the newer population I stars formed with a fair bit; the older II with less; the original III would have formed before there was any.
The difference the size of the star makes is just whether it is still here. The largest stars die fast so all the ones we see are young; population III stars would only still be around if they were a bit smaller than the sun. Does that go with what you were saying?
awjt at February 11th, 2014 18:38 — #15
If type III stars formed from "original material," as you said, then what I was saying is moot. I was postulating that if these type III stars came from previous stars, then those previous stars would have created some metals before they supernovaed. And if that were the case, then there would have to have been some separation mechanism to move the heavier elements away, leaving just the hydrogen to make these stars.
But if these oldies didn't come from previous stars, then I guess the theory is that they came from cooled material that condensed directly from the big bang. And that this thing is only 6000 ly away because it survived all the galactic mergers and acquisitions untouched for the last ~14 billion years.
If we developed faster-than-light space travel, this is one of the first places I'd visit. What if it has a mega-old planet orbiting it, with old civilizations? Maybe they're nice?
boundegar at February 11th, 2014 21:51 — #16
It's the Excession, of course.
newliminted at February 11th, 2014 23:23 — #17
halloween_jack_ at February 12th, 2014 07:41 — #18
Heh, first thing I thought of.
From the original article:
Tiny class M red dwarfs may live for up to a trillion years – no red dwarf has ever died in the Universe, because the Universe itself isn’t old enough yet.
maggiekb at February 16th, 2014 10:54 — #19
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