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First Stars III
Contact:
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Poster
Title: The weak s-process at low metallicity Author(s): Pignatari Marco Abstract: In massive stars (M > 10 Msun) the s-process (slow neutron capture process) mainly works during convective He-burning core and convective C-burning shell and it produces the major part of the s isotopes between the Fe peak and the Sr peak in the Solar System distribution (the weak s component). The main neutron source is the Ne22(alpha,n)Mg25 reaction, where the Ne22 amount depends on the initial CNO abundances. For this reason, the neutron production by Ne22 depends on the initial metallicity of the star, affecting the s-process distribution beyond iron. We present weak s-process calculations for models with different initial star masses (M = 15,20,25,30 Msun) at low metallicity. The most important uncertainties in the nuclear network and in the intial isotopic distribution are considered and discussed.
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