# Pop 111 stars

Gold Member
Dearly Missed
http://arxiv.org/abs/astro-ph/0507340

Nucleosynthesis of PopIII Core Collapse Supernovae and the Abundances of Extremely Metal Poor Stars
Authors: Marco Limongi (INAF-OAR), Alessandro Chieffi (INAF-IAS)
Comments: 6 pages, 4 figure, Proceedings of the IAU Symp. No. 228 "From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution", V.Hill, P.Francois & F.Primas eds

We present a new analysis of the abundances observed in extremely metal poor stars based on both a new generation of theoretical presupernova models and explosions of zero metallicity massive stars and a new abundance analysis of an homogeneous sample of stars having [Fe/H]<-2.5 (Cayrel et al. 2004).

## Answers and Replies

Science Advisor
Gold Member
What mass range for Pop III stars? From that paper
The two lower panels of Figure 2 shows the comparison between the AGV04 star and the ejecta provided by a generation of massive stars (in the mass range 13-80 M) averaged over a Salpeter IMF for two choices of the slope $$\alpha$$ . In particular, in the standard case ($$\alpha$$=-2.35), where the low mass massive stars dominate, N and O are both underproduced while Al is quite well fitted. An opposite behavior is found when the slope of the IMF is lower ($$\alpha$$=- 0.35) and the relative contribution of the more massive stars is higher. In any case N is significantly underestimated because the high primary N production occurs in a very narrow mass interval around the 25 M.
So not so very massive after all...
I wonder, what about the [102 - 104]M range?
Garth

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Science Advisor
Gold Member
A very speculative paper in my estimation.

misskitty
What does all this really mean?

~Kitty

Science Advisor
Gold Member
misskitty said:
What does all this really mean?

~Kitty
That our knowledge of the first stars that formed out of the products of the BBN is very sketchy and speculative.

What we do know is:
1. There is very early metallicity observed in Lyman alpha forests of quasar spectra, back to z>6.
2. There was an extended period of re-ionisation of the IGM at an even earlier period prior to z=10.5.
3. Stars forming out of a primordial gas with little or zero metallicity would be more massive than PopI or PopII stars. This is because metallicity is important to radiate away energy to enable a proto-star to collapse; without it greater gravitational forces are required. Once formed massive stars are expected to have only short lifetimes and they and their demise are expected to have been very bright events. Such bright PopIII stars have not been observed, but it is conceivable that their hyper-novae could be the source of the background GRBs.
This population could therefore be the source of the re-ionisation and early metallicity, that is if there are enough of them.
4. There are massive black holes in galactic centres, which may have preceded and been part of the formation of the galaxies themselves.
5. There seems to be about 10X the amount of mass in galactic halos and clusters than can be directly observed. This may be partially or totally accounted for by BH's of various masses.

So it is probably correct to say that there are a lot of BHs about. Some of these may be the end product of a ubiquitous population of PopIII stars. The question is of what mass range, and why have these PopIII stars not been observed?

Garth