The 1st stars in the universe formed earlier than thought

Mar 19, 2020
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Seems that we keep reading about everything forming earlier and earlier than previously proposed. Galaxies, stars, black holes, all apparently forming much earlier then BB physics (had) predicted, or so it seems. Well, as most "models" predicted. One must assume (hope?) that the folks who have been telling us all this stuff have some wiggle room up their theories.

As more and more of these "early birds" are found, one can only wonder what the earliest really is. It would appear that we still don't have the faintest glimmer, figuratively and literally!

Could there be an inherent flaw in the prevailing BB dogma? Stay tuned.........
 
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Seems that we keep reading about everything forming earlier and earlier than previously proposed. Galaxies, stars, black holes, all apparently forming much earlier then BB physics (had) predicted, or so it seems. Well, as most "models" predicted.
Did the models claim 400 million years was too early for formation?

One must assume (hope?) that the folks who have been telling us all this stuff have some wiggle room up their theories.
Yes, that's very likely, but future observations (e.g. JWST) will improve the unwanted degrees of wiggle. Part of the problem is trying to understand how having only hydrogen and a little helium would form a star, how big they could be, etc. These stars don't exist even in the old globular clusters.

Could there be an inherent flaw in the prevailing BB dogma? Stay tuned.........
I suspect all is in order, but we still need observations to help build better models.
 
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I suspect all is in order, but we still need observations to help build better models.
Helio, I have seen a number of proposals for the first galaxies, stars, etc over the years. For galaxies, it seems that many started around 1 billion years after BB, or they used to. Then they got younger and younger. It seems like every year or so they are re-modeled based on new observations rather than theory. Clearly empirical evidence is (or should be) defining.

So , have been watching the time-frame on these "original" objects appear to go down over time, not in "strict" keeping with most BB models (at those times). Not even sure what the latest story is, nor does anyone else I suspect.

As you suggest, the primary aspects of BB physics is probably correct. Details are the devil as usual. Hoping for the JWST to tell us more, assuming it ever gets up there.
 
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Helio, I have seen a number of proposals for the first galaxies, stars, etc over the years. For galaxies, it seems that many started around 1 billion years after BB, or they used to. Then they got younger and younger. It seems like every year or so they are re-modeled based on new observations rather than theory. Clearly empirical evidence is (or should be) defining.
That's sounds logical. The objective evidence available to tweak that early period is very scant, though the overall age does come with strong evidence.

So , have been watching the time-frame on these "original" objects appear to go down over time, not in "strict" keeping with most BB models (at those times). Not even sure what the latest story is, nor does anyone else I suspect.
The article seems to strongly discount the 500M to 1B yr period for early formation. These stars and galaxies, regardless of their formation period, must exist to explain today's stars and galaxies, reionization, etc., so it's just a matter of time before equipment and techniques get us to where we need to be.

I am a little surprised that more isn't known. I recall a U Texas paper that, among other claims, revealed a galaxy estimate for the universe of roughly 2 trillion. It wasn't that long ago the estimate was 250 billion. They too used lensing and incredible subtraction techniques to let us see those more distant galaxies.

It is interesting how the 13.8 B yr. age is so accurate, though it was 13.7 B years a year ago or so. But that is due to very detailed evidence found in things like the CMBR, so the BBT requires each piece of the puzzle to be better resolved even though we have all the side pieces in place, so to speak. This isn;t surprising given how broad BBT is.
 
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Yes, the existing data is very poor, after reading up on Pop-III stars. They are in fact hypothetical, and deemed (by many) to have been formed exclusively as super giants, with 100s of SMs. Other concepts put them in a range of sizes, with some of them still existing today. It seems that this is all based on metallicity.

I recall reading, not sure where, that some smaller stars could have formed very early, during the formation of Pop-III stars, and that a few of them still exist. Seem to recall that one super-low metallicity star was observed in a binary in the Milky Way, but don't recall the details.

There is no proof that the earliest stars (Pop-III) were all super-giants and now long gone. Was surprised to hear that there are none in globular clusters, but then that observation may simply be defined as size, rather then metallicity? How can you measure the metallicity of all (e.g.) 100,000 stars in a cluster?

I do recall the formation of blue stars in globular clusters (GCs), by the fusion of two old yellow stars. The combined mass of hydrogen was enough to light them up as blue giants. Is it possible that some of the stars in GCs are actually fused Pop-III stars that started smaller than models suggest they should?

It seems likely that there are a few Pop-III stars out there that are low mass and long-lived. If so, they would offer unique opportunities to study the earliest stars.
 
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Seem to recall that one super-low metallicity star was observed in a binary in the Milky Way, but don't recall the details.
Yes, but even these are likely not considered in the Pop III class. There were no metals for the first stars since Li and Be were so rare.

Was surprised to hear that there are none in globular clusters, but then that observation may simply be defined as size, rather then metallicity?
Those clusters consists of very old stars, but only the less massive stars survive for very long periods, and smaller stars are more convective so as they produce heavier elements. These, I assume, would rise to the surface, and their spectrum will reveal their greater metallicity.

How can you measure the metallicity of all (e.g.) 100,000 stars in a cluster?
IIRC, the Sloan Survey used fiber optics that ran through metal templates to align perhaps a few hundred stars for each imaging section to get the spectrum of each star. The Hobby-Eberly a year or so ago was taking time to do something similar but on a larger scale with its 9 meter mirror, and all for spectroscopy.

Is it possible that some of the stars in GCs are actually fused Pop-III stars that started smaller than models suggest they should?
Good question. It's my understanding that these clusters are still enigmatic as to how they are what they are.

It seems likely that there are a few Pop-III stars out there that are low mass and long-lived. If so, they would offer unique opportunities to study the earliest stars.
Outside of the globular cluster regions that are normally outside the galactic plane, it might take a rogue intergalactic star to remain unaffected by the spewing of normal stars, novae, and supernovae. But it would suffer with growing metalicity over time and, being small, the convective issue as mentioned above.
 
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Noting supernova, your comments have led me to two mechanisms I was unaware of for the end-stage of "super giant" stars :

"Photodisintegration" and "Pair-instability" supernova. The former leads to black holes and a lot of ejecta, the latter only to ejecta, no remnant. Both are apparently theoretical as I find no immediate evidence that they even occur. They would certainly be rare in our neighborhood. I can see that Pair-instability supernova are quite unique, but Photodisintegration supernova appears closely related to the standard core-collapse of smaller giant stars. I don't seem to find an exact size relating to either mechanism. Perhaps they are competing theories on the end fate of super giants.

This is pretty wild stuff. Are there any other proposed fates for super giant stars? Any that collapse into a BH without radiation or ejecta? Seem to remember that somewhere, but it might be mish-mashed from some of my readings on this rapid course in Pop-III stars, etc.

My first and only prior exposure to super giant stars is Eta Carinae, estimated around 150 SMs. Apparently the largest star known to exist in the Milky Way. No doubt you are aware of this star, and it is believed to be short-lived, and could go off at any moment. As this star is so large, is it expected to undergo one of the above supernova mechanisms? A remnant BH would quickly distinguish the two mechanisms, one would think.

Very interesting story on the Sloan Survey. Will have to do some looking into that.
 
Very interesting story on the Sloan Survey. Will have to do some looking into that.
Wiki has a nice article:

Wiki said:
The spectrograph operates by feeding an individual optical fibre for each target through a hole drilled in an aluminum plate. Each hole is positioned specifically for a selected target, so every field in which spectra are to be acquired requires a unique plate. The original spectrograph attached to the telescope was capable of recording 640 spectra simultaneously, while the updated spectrograph for SDSS III can record 1000 spectra at once. Over the course of each night, between six and nine plates are typically used for recording spectra. In spectroscopic mode, the telescope tracks the sky in the standard way, keeping the objects focused on their corresponding fibre tips.

Every night the telescope produces about 200 GB of data.
 
In the 1970s, searches for Population III stars looked at red dwarfs (very logical because these stars burn H very slowly and last much longer than 13.8 billion years). None found. Population III star EOS modified to make them larger, burn faster, and disappear earlier in BB cosmology while seeding the early universe with r-process and s-process elements. Astronomy is correct to search for this type of star, predicted by BBN and a requirement it seems. So far Population III stars remain undiscovered, i.e. not verified like other stars. Perhaps the issue is BBN. The universe never existed in the primordial condition for BBN, thus the creation of Population III stars did not take place in the early universe. If this is the situation (Pop III simply never there), much is at stake for BB cosmology now and the search for these 1st generation stars. I prefer confirmed stellar spectra to show Pop III stars existed or are still in the universe.
 
Astronomy is correct to search for this type of star, predicted by BBN and a requirement it seems. So far Population III stars remain undiscovered, i.e. not verified like other stars. Perhaps the issue is BBN.
What is the BBN? Is this the same as the BBT (Big Bang Theory)?

BBT also predicts that they will be incredibly hard to see given that their more easily detectable light would have zipped by us billions of years ago. The JWST might get lucky since it is more focused in the IR band and Pop III stars have large redshifts.

The universe never existed in the primordial condition for BBN, thus the creation of Population III stars did not take place in the early universe.
Given that Pop II stars require metals that were produced by Pop III stars, and that the BBT has only H and He (9 to 1 number ratio) as the only atoms to form (Li & Be were very low in number), then I am puzzled by what you mean.

If this is the situation (Pop III simply never there), much is at stake for BB cosmology now and the search for these 1st generation stars. I prefer confirmed stellar spectra to show Pop III stars existed or are still in the universe.
It's the other 20 or so lines of evidence that have produced an overwhelming confluence of validity for the theory, hence it is fair to assume the Pop III discoveries are inevitable once we can see more (better scopes). This is similar to planet formation theory that "suffers" due to the fact that most exoplanets are large (contrary to the models). But this was expected since the small ones are much harder to detect.
 
FYI Helio. BBN = Big Bang Nucleosynthesis. Observations of Gamma-Ray Burst Reveal Surprising Ingredients of Early Galaxies "These galaxies have more heavy elements than have ever been seen in a galaxy so early in the evolution of the Universe. We didn't expect the Universe to be so mature, so chemically evolved, so early on…"

In 1948, BBN had a very different equation of state for the early universe, Universe Creates All Elements in the Periodic Table in 10 Minutes, “Nineteen years after Edwin Hubble’s discovery that the galaxies seem to be running away from one another at fabulously high speeds, the picture presented by the expanding universe theory—which assumes that in its original state all matter was squeezed together in one solid mass of extremely high density and temperature—gives us the right conditions for building up all the known elements in the periodic system. According to calculations, the formation of elements must have started five minutes after the maximum compression of the universe. It was fully accomplished, in all essentials, about 10 minutes later.” —Scientific American, July 1948

The current BBN model is very different than the original. No Population III stars, could overthrow the current BBN model.
 
FYI Helio. BBN = Big Bang Nucleosynthesis. Observations of Gamma-Ray Burst Reveal Surprising Ingredients of Early Galaxies "These galaxies have more heavy elements than have ever been seen in a galaxy so early in the evolution of the Universe. We didn't expect the Universe to be so mature, so chemically evolved, so early on…"
But I take this in the context that only more recently have models surfaced to explain how massive Pop III could form, so early compositional models had to struggle, I expect. This is still new and exciting territory.

In 1948, BBN had a very different equation of state for the early universe, Universe Creates All Elements in the Periodic Table in 10 Minutes, “Nineteen years after Edwin Hubble’s discovery that the galaxies seem to be running away from one another at fabulously high speeds, the picture presented by the expanding universe theory—which assumes that in its original state all matter was squeezed together in one solid mass of extremely high density and temperature—gives us the right conditions for building up all the known elements in the periodic system. According to calculations, the formation of elements must have started five minutes after the maximum compression of the universe. It was fully accomplished, in all essentials, about 10 minutes later.” —Scientific American, July 1948
This was about 6 years before Hoyle introduced our more modern understanding thanks to his brilliant work on C12 resonance.

The current BBN model is very different than the original. No Population III stars, could overthrow the current BBN model.
Agreed, but the current BBN isn’t about metal production.

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"Agreed, but the current BBN isn’t about metal production." Yes, and that is the problem if there never were Population III stars. Those first stars would then contain some metals and so far, Population III is not confirmed. Deep redshift surveys as I cited show metals still in the gas. This would be bad news for current BBN thinking if no Pop III stars in the beginning.
 
"Agreed, but the current BBN isn’t about metal production." Yes, and that is the problem if there never were Population III stars. Those first stars would then contain some metals and so far, Population III is not confirmed. Deep redshift surveys as I cited show metals still in the gas. This would be bad news for current BBN thinking if no Pop III stars in the beginning.
Right, it would be very disruptive if Pop III stars are not found, eventually. The 1948 view has been refuted with things like the Lyman-Alpha Forest.

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Very good. Gas found between galaxies is not pure or pristine either, some metal shows up. https://astronomy.com/news/2019/08/how-galaxies-live-breathe-and-die.
Yes, but there are many times I have to separate kind from degree. The metals are there but, apparently, to the degree expected.

I have seen more than one astronomer and prominent solar "expert" say the Sun is white because its light has all the colors. It's shocking to hear this or see it in print since they well know, assuming they get a tiny bit serious about it, that the light from all stars include the entire spectrum of colors, so suddenly blue stars and red stars are now white by their erroneous definition.

Though, in retrospect, perhaps the Forest isn't a fair counter to a metal producing BBN, after all.

The CMBR, once again, may be the key to refuting it.
 
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Helio, yes the CMBR is the cornerstone of current BB cosmology. Showing metal abundances starting from the pristine and primordial gas clouds created during the BBN phase (zero metals, possible bit of Li) that *evolved* before Pop III stars that then evolved into Pop III stars, that then continued to evolve to the present stars with metals observed is not easy. You can see that when comparing metallicity values using the [Fe/H] log scale. I periodically compare the Sun [Fe/H] measure to other stars that have exoplanets reported at http://exoplanet.eu/ and https://exoplanetarchive.ipac.caltech.edu/index.html, including their stellar evolution ages provided. I plan to wait for the announcement that Pop III stars are confirmed like Population I and II stars. Searches continue, still MIA apparently :)
 
Helio, yes the CMBR is the cornerstone of current BB cosmology. Showing metal abundances starting from the pristine and primordial gas clouds created during the BBN phase (zero metals, possible bit of Li) that *evolved* before Pop III stars that then evolved into Pop III stars, that then continued to evolve to the present stars with metals observed is not easy.
How could H and He "evolve" into the post Pop III levels of metallicity, which then gave us the Pop II stars, The fusion temperatures necessary require some of these very massive stars, so if we can eventually see to a time just after atoms formed (Reionization) and no Pop III are found, then a very big challenge will be on the table.

I would be surprised to see any cosmologist be worried about the lack of Pop III after the 400 M yr. limit per the article. Remember, "absence of evidence is not evidence of absence."

Searches continue, still MIA apparently :)
Yep.
 
Seems that we keep reading about everything forming earlier and earlier than previously proposed. Galaxies, stars, black holes, all apparently forming much earlier then BB physics (had) predicted, or so it seems. Well, as most "models" predicted. One must assume (hope?) that the folks who have been telling us all this stuff have some wiggle room up their theories.



As more and more of these "early birds" are found, one can only wonder what the earliest really is. It would appear that we still don't have the faintest glimmer, figuratively and literally!



Could there be an inherent flaw in the prevailing BB dogma? Stay tuned.........
Of course we have a glimmer and of course the new cosmology famously solves the star age problem. Before the cosmic background radiation spectra was discovered, the big bang cosmologies differed with a factor 2 on universe age [!] and there were stars that were definitely too old for some of the expansion rate measurements. That does not happen any longer, stars will overlap at worst - star ages are poorly understood - but not break the cosmology.

All thanks to the fantastic advancements you deride! Which changes, by the way, show that there is no 'dogma' involved. Your 'dogma' proposition is just a common anti-BB dogma. ;-)

Here is the thing: understanding galaxies is the new research edge in cosmology. "Perhaps the simulations' single biggest lesson so far is not that scientists need to revise their overarching theory of cosmology, but rather that problems lurk in their understanding of astrophysics at smaller scales. In particular, their theory of star formation comes up wanting, Springel says." [ https://www.sciencemag.org/news/2018/05/galaxy-simulations-are-last-matching-reality-and-producing-surprising-insights-cosmic.
 
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My observations of newer stars, galaxies, etc. all apparently forming much earlier then BB physics (had) predicted IS based on the "new cosmology". And there has been some wiggling going on, although some are sure to deny it. Helio certainly had no problems with refining the new cosmology.

And yes, it may sound derisive to people who lack a sense of humor. Having read though hundreds of posts and articles on the BB and events following it, there is no real consensus.

As I recall, some have posted that 'we know 99.9% about everything in the universe'. Such comments are due for some derisive commentary simply based on the arrogance of such notion(s). No hostility meant, but we are far from absolutes in any of this.

Just for an example, there is no hard evidence that population III stars ever existed. They are purely hypothetical. But they do play a role in a lot of BB models. Some accept them as fact, and that anyone questioning them is ill-informed.

Some will say that facts are not dictated. To be sure, facts are demonstrated. And no one has demonstrated population III stars existence, much less beyond doubt. I prefer my facts be beyond doubt, and as far as BB goes, we are not there, by a long shot.
 
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Yes, but there are many times I have to separate kind from degree. The metals are there but, apparently, to the degree expected.



I have seen more than one astronomer and prominent solar "expert" say the Sun is white because its light has all the colors. It's shocking to hear this or see it in print since they well know, assuming they get a tiny bit serious about it, that the light from all stars include the entire spectrum of colors, so suddenly blue stars and red stars are now white by their erroneous definition.



Though, in retrospect, perhaps the Forest isn't a fair counter to a metal producing BBN, after all.



The CMBR, once again, may be the key to refuting it.
Well, "white hot" is technically black body radiation as all other hot objects including colored stars, it is a very pity description.

So is Pop III stars, which have a lot of problems such as how they would be formed. Don't be surprised if such objects turn out to be direct collapse objects that doesn't conform to our idea of a star. But BBN is, as you note, very secure as a key pillar of current LCDM cosmology. If we want to look at missing parts of the cosmology, we have the energy range from inflation at ~ 10^-3 of Planck energy down to standard particle range at ~ 10^-19 of Planck energy, or matter/antimatter asymmetry, et cetera.

I know it is fashionable to obsess over current cosmology, but until 40 years ago we knew very little what the universe was - what it consisted of, how old it was and what was its destiny - but today we know 100 % of the universe content, how old it is and that it is destined for heat death (at some 1 % uncertainty). I wouldn't obsess over Pop III, but at the same time it is an interesting part where we may expect future discoveries.
 
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My observations of newer stars, galaxies, etc. all apparently forming much earlier then BB physics (had) predicted IS based on the "new cosmology". And there has been some wiggling going on, although some are sure to deny it. Helio certainly had no problems with refining the new cosmology.

And yes, it may sound derisive to people who lack a sense of humor. Having read though hundreds of posts on the BB and events following it, there is no real consensus.

As I recall, some have posted that 'we know 99.9% about everything in the universe'. Such comments are due for some derisive commentary simply based on the arrogance of such notion(s). No hostility meant, but we are far from absolutes in any of this.
Oy. Is that your reaction to responses that has content? What's with the personal attack, how can you claim "no hostility", and what does it say of your own person?

But as it happens I enjoyed Helio's comment and put in some refinement of the current research edge myself. That we know 100 % of the universe matter-energy content is simply a matter of fact, I don't see why it would bother anyone to remind us of it. And I think we agree that science is not about absolutes, while also minding that nature has absolutes (water is one oxygen and two hydrogen atoms, there is a universal speed limit and LCDM is absolutely the best cosmology we know of so far).
 

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