<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1522" name=GENERATOR></HEAD>
<BODY>
<DIV><SPAN class=931331419-28112005><FONT face=Arial color=#0000ff size=2>My
graduate simulation work on Pop III stars, from formation to late life core
ignition events, demonstrated that they had a significantly higher mass
function, and much larger stars may be stable (up to 200-500
Msol). Consequently, the population burns much faster than Pop II.
They explode much more readily too. Smaller Pop III stars
are very long-lived, however; you'd expect to see them
everywhere today if they existed in any significant number, with
photospheric metallicities much the same as when they formed. Since we don't,
this is another argument for the high mass function. You
can build Pop II metallicities from scratch in n*10^6 years, where 1 < n
< 100, depending on your mass function.</FONT></SPAN></DIV>
<DIV><SPAN class=931331419-28112005><FONT face=Arial color=#0000ff
size=2><BR>Reason</FONT></SPAN></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
extropy-chat-bounces@lists.extropy.org
[mailto:extropy-chat-bounces@lists.extropy.org]<B>On Behalf Of </B>Robert
Bradbury<BR><B>Sent:</B> Monday, November 28, 2005 9:09 AM<BR><B>To:</B> ExI
chat list<BR><B>Subject:</B> Re: [extropy-chat] Qualia
Bet.<BR><BR></FONT></DIV>Adding to Amara's comment...<BR><BR>Since we are
detecting supernova's out to 10+ billion light years, it is clear that the
heavier elements synthesized through the r&s-processes that Amara points
out have been around in the Universe for quite some time (probably 2+ times
the age of our solar system). The creation of elements heavier than iron
through the r(rapid)-process comes from stars which go supernova while the
evolution of those elements derived from the s(slow)-process takes place in
lower mass (< 8 M_sun) stars. But the lower mass stars which are
quite abundant today are going to take some time (billions of years) to build
up large quantities of s-process elements.<BR>Most stars which we see *are*
evolving relatively large quantities of C/N/O as they are essential elements
in the natural fusion processes that take place in stars. Of course
these are only distributed into the galaxy to seed other stars/solar systems
late in stellar lifetimes when they go through red-giant or nova/supernova
phases. So C/N/O as well as heavier elements largely came from stars
similar to or heavier than our sun in mass which "died" billions of years
ago. The discussions which are interesting are what are the minimal
element abundances necessary on planets for life to evolve. I'll always
toss into the mix that it seems that evolution (nature) is clever enough to
work around most constraints with respect to element abundances so long as
there is carbon around and you have temperatures which can allow the formation
of complex carbon based structures. Worth noting is that carbon is one
of the more abundant elements in the universe (after you discard H &
He).<BR><BR>Robert<BR><BR></BLOCKQUOTE></BODY></HTML>