Free Republic
Browse · Search
News/Activism
Topics · Post Article

To: aristeides; longshadow; ASA Vet; VadeRetro; general_re
Taken from this essay:

http://nedwww.ipac.caltech.edu/level5/ESSAYS/Carr/carr.html

The term ``Population III'' has been used to describe two types of stars: (1) the ones which form out of the pristine gas left over after cosmological nucleosynthesis and generate the first metals; and (2) the ones which have been hypothesized to provide the dark matter in galactic halos. Stars of the first kind definitely exist, but may not warrant a special name. Those of the second kind may not exist, because galactic halos could also be composed of some sort of elementary particle, but they certainly warrant a special name if they do, and they could have many interesting cosmological consequences. Population III stars of either kind could be pregalactic, but they might also have formed during the first phase of galaxy formation.

It is not necessarily required that Population III stars be pregalactic. Some of the arguments for their having a different initial mass function (IMF) would also apply if they formed protogalactically, and this gives rise to a less radical hypothesis, in which the Population III objects form during the first phases of protogalactic collapse. In this case, the Population III stars or their remnants would be confined to galaxies, whereas they would be spread throughout space in the pregalactic case.

39 posted on 10/30/2002 7:27:06 PM PST by RadioAstronomer
[ Post Reply | Private Reply | To 29 | View Replies ]


To: RadioAstronomer
The term ``Population III'' has been used to describe two types of stars: (1) the ones which form out of the pristine gas left over after cosmological nucleosynthesis and generate the first metals;.... [snip]

Just a point of clarification; if I understood the original article correctly, the star in question is NOT one of the original pre-galactic giants. It appears to be at least one generation removed from that, as it does have SOME "heavy" elements that could not have been synthesized within its own core; hence, there MUST have been a generation of stars prior to its formation that DID support synthesis, and these must be much larger than 0.8 solar masses to get synthesis of anything beyond helium.

41 posted on 10/30/2002 8:55:37 PM PST by longshadow
[ Post Reply | Private Reply | To 39 | View Replies ]

To: RadioAstronomer
Hi, RadioAstronomer! Here's a bump for an interesting read!
42 posted on 10/30/2002 9:22:34 PM PST by Alamo-Girl
[ Post Reply | Private Reply | To 39 | View Replies ]

To: RadioAstronomer
OK, here's a question. If heavy elements were created in the cores of first-generation stars, and this star's been around for the entire time, wouldn't it have the same concentration of heavy elements as the rest of the universe? I mean, it's not like it's been frozen in time all this time.
47 posted on 10/31/2002 12:12:20 PM PST by inquest
[ Post Reply | Private Reply | To 39 | View Replies ]

Free Republic
Browse · Search
News/Activism
Topics · Post Article


FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson