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Author Topic: Why are there no first generation stars?  (Read 5621 times)

Offline Vern

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Why are there no first generation stars?
« on: 21/10/2009 17:21:45 »
While doing research for this post I realized that first generation stars do not seem to have ever existed. Such stars would contain no heavy elements, since the heavy elements must be created in novas.

Edit: Here's the pertinent quote from the link:

Quote from: the link
No one has detected stars without heavy elements above Helium. In, fact astronomers have observed evidence of elements like carbon and iron in objects that are claimed to be from the early eras of the Big Bang.4,5,6 Indeed, there is evidence that some GRBs contain metals such as iron and magnesium.7 Heavier elements like carbon or iron, according to big bang ideas, could not be produced in the big bang itself but instead must have been produced in supernova explosions that took place when large stars died. Astronomers who operate by naturalistic assumptions and do not allow for supernatural creation as Genesis describes must resort to complicated scenarios like these to explain the origin of the chemical elements.
« Last Edit: 21/10/2009 17:24:36 by Vern »


 

Offline graham.d

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Why are there no first generation stars?
« Reply #1 on: 21/10/2009 17:43:59 »
Isn't it the case that these stars did not last long and would have only existed in the early universe? If so it would be very difficult to see any as they would have to be very far off. Even though they were undoubtedly very large and bright, it would be very difficult to detect them with present telescopes. The lack of detection is therefore no indication of their lack of existence.

The comment sounds like a "creationist's creation" to try to argue against the concept that the universe may be a natural phenomenon.
 

Offline Vern

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Why are there no first generation stars?
« Reply #2 on: 21/10/2009 18:40:07 »
The link did come from a creationist site. However, I am no creationist; I was just using the research. I had first seen reference to the recent gamma ray burst at a better site. When I found it again the reference to the heavy elements wasn't there.
Quote
Even though they were undoubtedly very large and bright, it would be very difficult to detect them with present telescopes. The lack of detection is therefore no indication of their lack of existence.
The opposite would probably hold though. If the earliest light we could detect contained no evidence of heavy elements, it would be evidence for the Big-Bang scenario.
« Last Edit: 21/10/2009 18:42:45 by Vern »
 

Offline LeeE

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Why are there no first generation stars?
« Reply #3 on: 21/10/2009 22:32:33 »
I think that the phrase "...the early eras of the Big Bang' need to be qualified here.

Also, the original articles that the creationist article references say that stars need to 'evolve' for at least 700 million years before they could create the heavier elements.  This seems way too long to me, as very large stars only stay on the main sequence for as little as a few million years.  This would give plenty of time for the heavy elements to form, depending on how long that 'early era' of the universe is defined to be.
 

Offline Vern

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Why are there no first generation stars?
« Reply #4 on: 21/10/2009 23:46:49 »
We could argue that the early stars tended to be huge due to the abundance of close packed star stuff in the early universe. Huge stars die fast. So, there is room for stars to go nova and create the heavy elements. I agree that the creationist article fudged the numbers a little.

The main point I wanted to make is that the absence of first generation stars does not preclude the Big Bang scenario, but the presence of first generation stars would strongly support it. If the universe has been around forever, there is no possibility that first generation stars will be found.
« Last Edit: 21/10/2009 23:56:04 by Vern »
 

Offline PhysBang

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Why are there no first generation stars?
« Reply #5 on: 22/10/2009 14:19:30 »
We could argue that the early stars tended to be huge due to the abundance of close packed star stuff in the early universe. Huge stars die fast. So, there is room for stars to go nova and create the heavy elements. I agree that the creationist article fudged the numbers a little.
I don't doubt that they fudged the numbers, but even if they are right and it takes 700 million years for stars to produce enough metals to create uniform populations of stars with metal content, that's fine. I don't think that we can resolve stars from that era of the universe. That is, these stars would be so far away that it would be impossible with current technologies to see the individual stars rather than simply the galaxies or galaxy clusters that they are in. (It may be able to detect the presence of these stars in other ways than simply seeing them individually.)
Quote
The main point I wanted to make is that the absence of first generation stars does not preclude the Big Bang scenario, but the presence of first generation stars would strongly support it. If the universe has been around forever, there is no possibility that first generation stars will be found.
There are scenarios where there might be the creation of 1st gen. stars. I haven't gone through all the details put forward by Quasi-Steady State Cosmology, but the model has the creation of light elements in high-dense areas. This might create areas of only light elements (though I doubt it). QSSC doesn't really have much to support it, though, and it certainly doesn't do anything for creationists!
 

Offline Vern

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Why are there no first generation stars?
« Reply #6 on: 22/10/2009 20:51:39 »
According to this Wiki we should more likely find first-generation stars in small galaxies than large galaxies. But small galaxies should be younger it seems to me.

Quote from: the link
The next generation of stars was born out of those materials left by the death of the first. The oldest observed stars, known as Population II, have very low metallicities;[2] as subsequent generations of stars were born they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations. As those stars died, they returned metal-enriched material to the interstellar medium via planetary nebulae and supernovae, enriching the nebulae out of which the newer stars formed ever further. These youngest stars, including the Sun, therefore have the highest metal content, and are known as Population I stars.

Across the Milky Way, metallicity is higher in the galactic centre and decreases as one moves outwards. The gradient in metallicity is attributed to the density of stars in the galactic centre: there are more stars in the centre of the galaxy and so, over time, more metals have been returned to the interstellar medium and incorporated into new stars. By a similar mechanism, larger galaxies tend to have a higher metallicity than their smaller counterparts. In the case of the Magellanic Clouds, two small irregular galaxies orbiting the Milky Way, the Large Magellanic Cloud has a metallicity of about forty per cent of the Milky Way, while the Small Magellanic Cloud has a metallicity of about ten per cent of the Milky Way.
 

Offline Soul Surfer

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Why are there no first generation stars?
« Reply #7 on: 24/10/2009 00:07:01 »
Large stars run through their lives very much quicker than small stars and may only last a few million years beefore they explode and spread most of thir material through space.  The heavy elements are a catalyst and only a very small quantity of them is needed to have a fundamental effect on the speed of the nuclear synthesis reactions.  Altough there was only a very small amount of higher atomic weight nucleii formed in the big bang it was not zero and this had a very big effect on the ease of the syenthesis reactions in the first stars which were probably much larger than the current generation of stars.
« Last Edit: 24/10/2009 00:09:08 by Soul Surfer »
 

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Why are there no first generation stars?
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