# of star generations needed to produce observed element abundances

In article ,
writes:
My question is this - approximately how many "generations" of stars
needed to supernova to produce the observed abundances of high Z
elements currently observed?

Suppose you start with 3000 solar masses of hydrogen gas. At current
star formation efficiency, you might form 30 solar masses of stars.
In the early Universe, with an initial mass function strongly biased
to high masses, this might consist of just a single star. This star
would become a supernova, and you might get a solar mass of heavy
elements out of it. This is already enough to give the heavy element
abundances seen in globular clusters. If you want the _solar_ metal
abundance, though, you need something like 100 more generations of
processing, especially as the IMF will produce lots more low-mass
stars after the first few generations (we think!).

Of course what I've left out is that not all the hydrogen gas will
collapse into star-forming clumps. But on the other hand, the star
formation efficiency in the early Universe might have been a lot
higher than what we see today. So the above is really rough; the
true answer is that nobody knows for sure. It is a topic of very
active research, but I think the answer won't be known until JWST
data come in.

My second question is this - on earth we have a distilled amount of
high Z atoms. Is this density consistent with what was available in
the proto star that eventually became the sun and the planets?

The early solar nebula is thought to have been mostly hydrogen and
helium, like the Sun is today. Most of the hydrogen and helium have
escaped.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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Steve Willner wrote:
In article ,
writes:
My question is this - approximately how many "generations" of stars
needed to supernova to produce the observed abundances of high Z
elements currently observed?

Suppose you start with 3000 solar masses of hydrogen gas. At current
star formation efficiency, you might form 30 solar masses of stars.
In the early Universe, with an initial mass function strongly biased
to high masses, this might consist of just a single star. This star
would become a supernova, and you might get a solar mass of heavy
elements out of it. This is already enough to give the heavy element
abundances seen in globular clusters. If you want the _solar_ metal
abundance, though, you need something like 100 more generations of
processing, especially as the IMF will produce lots more low-mass
stars after the first few generations (we think!).

What's the approximate lifetime of these stars and is there currently
any conflict between the current solar metal abundances and the
# of generations needed to produce the abundance? There could either
have been too few generations or perhaps even too many (and so we
should
expect even higher abundances?

Thanks,

Ted