The minimum stellar metallicity observable in the Galaxy - AstrophysicsReport as inadecuate

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Abstract: The first stars fundamentally transformed the early Universe through theirproduction of energetic radiation and the first heavy chemical elements.
Theimpact on cosmic evolution sensitively depends on their initial mass functionIMF, which can be empirically constrained through detailed studies ofancient, metal-poor halo stars in our Galaxy.
We compare the lowest magnesiumand iron abundances measured in Galactic halo stars with theoreticalpredictions for the minimum stellar enrichment provided by Population III starsunder the assumption of a top-heavy IMF.
To demonstrate that abundancesmeasured in metal-poor stars reflect the chemical conditions at theirformation, and that they can thus be used to derive constraints on theprimordial IMF, we carry out a detailed kinematic analysis of a large sample ofmetal-poor stars drawn from the SDSS survey.
We assess whether interstellaraccretion has altered their surface abundances.
We find that accretion isgenerally negligible, even at the extremely low levels where the primordial IMFcan be tested.
We conclude that the majority of the first stars were verymassive, but had likely masses below ~140 M.

Author: Anna Frebel, Jarrett L.
Johnson, Volker Bromm



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