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BigDon
2007-Feb-28, 03:10 AM
Or at least very, very dirty?

(Whew! Raining furiously outside at the moment, with hail setting off car alarms!)

Anyway, when truely massive stars give up the ghost in that spectacular way that they do, and produce prodigious amounts of heavier elements, is it possible to form a new star out of mostly nitrogen or oxygen or other "metal"? I assume you would need a cluster of large stars so wave fronts could hit each other instead of just going "outward".

And would a heavier gas than hydrogen need less than the 80 or so Jovian masses to begin fusion? Sorry if this is worded awkwardly. Been thinking about this for a while. Even talked about it on a camping trip or two over the campfire.

Does anybody know of any youngish, seriously metal rich stars?

Thank you.

StupendousMan
2007-Feb-28, 02:10 PM
Anyway, when truely massive stars give up the ghost in that spectacular way that they do, and produce prodigious amounts of heavier elements, is it possible to form a new star out of mostly nitrogen or oxygen or other "metal"?


To answer this properly, one would need to do combine sophisticated simulation of a supernova explosion with hydrodynamic code and run it over a very, very wide dynamic range of timescales and spatial scales ... It certainly hasn't been done yet, nor will it be done properly in the near future. So the answer must be "well, maybe." But I would guess it's unlikely.



And would a heavier gas than hydrogen need less than the 80 or so Jovian masses to begin fusion?


This one I know. Stars which have large fractions of heavy elements can undergo hydrogen fusion at lower total masses than those made purely of hydrogen and helium. I recall one of my classmates playing with a stellar model code and finding that a star with roughly 90% uranium and 10% hydrogen could reach a stable equilibrium even at some absurdly small mass, like 1 or 2 Jovian masses. But that was a long time ago ...

You can find software to make models of stellar interiors in a number of places for free; why not grab one and play with it? You could answer some of your questions for yourself?

korjik
2007-Feb-28, 11:03 PM
If I remember right, most stars that supernova still are mostly hydrogen. The core on most large stars is really a fairly small fraction of total mass (I mean like 20% not 2%). I think this would give you a star that might be like 10 to 20 percent metal, but not much more. A high metal star would be bright for its mass

triclon
2007-Feb-28, 11:31 PM
If you somehow managed to get enough oxygen or other element lighter then iron to make a star, it could start nuclear fusion in its core. The star would have to be extremely massive, and would not last very long, and go supernova when its core started fusing iron. So far most (if not all) living stars in the universe are made mostly of hydrogen though, so I don't know if it can be done.

BigDon
2007-Mar-01, 03:31 AM
You can find software to make models of stellar interiors in a number of places for free; why not grab one and play with it? You could answer some of your questions for yourself?

StupendousMan, such things exist? Pray tell, were would I find one?

Thanks for the replies guys.

StupendousMan
2007-Mar-01, 04:15 PM
StupendousMan, such things exist? Pray tell, were would I find one?

Thanks for the replies guys.

http://theory.kitp.ucsb.edu/~paxton/EZ-intro.html

http://planck.phys.uwosh.edu/mike/82-304/zams/zams.html

And, to a lesser extent,

http://rainman.astro.uiuc.edu/ddr/stellar/advanced.html

The first edition of Carroll and Ostlie's book "An Introduction to
Modern Astrophysics" contains the source code for a simple
stellar model. I don't know if the more recent edition does ...