Kavli Affiliate: Anna Frebel
| First 5 Authors: Khalil Farouqi, Anna Frebel, Friedrich-Karl Thielemann, ,
| Summary:
Low-metallicity stars preserve the signatures of the first stellar
nucleosynthesis events in the Galaxy, as their surface abundances reflect the
composition of the interstellar medium from which they were born. Aside from
primordial Big Bang nucleosynthesis, massive stars, due to their short
lifetimes, dominate the ejecta into the interstellar medium of the early
Galaxy. Most of them will end as core-collapse supernova (CCSN) explosions, and
typical ejected abundance distributions, e.g. in terms of the
alpha-element-to-Fe ratios, reflect these contributions. Essentially all CCSNe
contribute 56Fe. Therefore, low-metallicity stars can be used to test whether
the abundances of any other elements are correlated with those of Fe, i.e.
whether these elements have been co-produced in the progenitor sources or if
they require either a different or additional astrophysical origin(s). The
present analysis focuses on stars with [Fe/H]<-2, as they probe the earliest
formation phase of the Galaxy when only one or very few nucleosynthesis events
had contributed their ejecta to the gas from which the lowest metallicity stars
form. This was also the era before low and intermediate mass stars (or type Ia
supernovae) could contribute any additional heavy elements. Following earlier
works into the origin of heavy r-process elements [1], we extend the present
study to examine Pearson and Spearman correlations of Fe with Li, Be, C, N, Na,
Mg, Si, S, Ca, Ti, Cr, Ni, Zn, Ge, Se, Sr, Zr, Ba, Ce, Sm, Eu, Yb, Lu, Hf, Os,
Ir, Pb, Th, and U, using high-resolution stellar abundance data from the SAGA
[2] and JINA [3] databases. The main goal is to identify which of the observed
elements (i) may have been co-produced with Fe in (possibly a variety of)
CCSNe, and which elements require (ii) either a completely different, or (iii)
at least an additional astrophysical origin.
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