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canuck
super member
Reged: 02/22/05
Posts: 129
Loc: Nova Scotia, Canada
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Recent (?) Hubble images of the Orion nebula revealed stars not seen before from earth-based telescope images. Apparently these are very young stars, as yet not burning hydrogen. What then would be their composition/fuel, just elementary particles and fused nuclei?
John V
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Jarad
Post Laureate
Reged: 04/28/03
Posts: 3850
Loc: Atlanta, GA
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Before a young star ignites fusion, it is just a condensing ball of whatever gasses were present in the cloud it formed from. Usually mostly hydrogen, with some helium and heavier elements that had been blown off by previous supernova's. They are still hot from the effect of gravity and pressure on the condensing gas (PV=nRT).
Jarad
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canuck
super member
Reged: 02/22/05
Posts: 129
Loc: Nova Scotia, Canada
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Jarad, thanks for the quick reply, which also raises a question. You wrote of young stars, gas ball, and previous 'coats' that were "blown off by previous supernova's". Do stars go through more than one supernova?
John V
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Anonymous
Unregistered
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No. One supernova event per star. Some percentage of the ejected material from a supernova event can find itself being used in the creation of another star.
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Jarad
Post Laureate
Reged: 04/28/03
Posts: 3850
Loc: Atlanta, GA
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When a large star goes supernova, it has used up the hydrogen in its core, but still has a lot of hydrogen in the outer layers, and also tends to blow off a trememdous amount of hydrogen as solar wind before it explodes. When it explodes, it blows a lot of that hydrogen and helium out into a huge cloud. It is possible for multiple smaller stars to form out of the left-over gasses in that cloud (and this is thought to be quite common - the shockwave of the explosion causes condensations to start which triggers new star formation).
The first generation stars were composed of almost all hydrogen, with some helium but nothing heavier. The second generation stars formed from the material blown out by 1st gen SN's, so contained more helium and some heavier elements. Later generations have higher proportions of heavier elements than earlier ones because there have been more SN's to blast the heavier elements into the various gas clouds.
Jarad
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Anonymous
Unregistered
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Quote:
The first generation stars were composed of almost all hydrogen, with some helium but nothing heavier.
There could been some trace lithium present according to some models. Observation of population III stars could confirm this, but thus far to my knowledge, pop III stars have not yet been observed directly.
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