S317p.28 — Clues About the First Stars from CEMP-no Stars

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Aug 4th at 6:00 PM until 6:00 PM

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Author(s): Georges Meynet3, André Maeder3, Arthur Choplin3, Raphael Hirschi1, Sylvia Ekström3, Cristina Chiappini2

Institution(s): 1. Keele University, 2. Leibniz-Institut fuer Astrophysik , 3. University of Geneva

The material used to form the CEMP-no stars presents signatures of material processed by the CNO cycle and by He-burning from a previous stellar generation called the source stars. In order to reproduce the absolute amounts of CNO elements observed at the surface of CEMP-no stars ([X/H] values), as well as the relative abundance ratios, for instance C/N, O/N or 12C/13C, some mixing between the two burning regions must have occured in the source stars and only the outer layers of the source stars, with modest amount coming from the CO core, must have been expelled either through stellar winds or at the time of the (faint) supernova event. With new models at low metallicity including rotational mixing, we shall discuss how the variety of abundances observed at the surface of CEMP-no stars can be reproduced. Some new results about the s-process nucleosynthesis by massive metal-poor rotating stars will also be presented.