SIMBAD references

2019A&A...622L...4A - Astronomy and Astrophysics, volume 622, L4-4 (2019/2-1)

Carbon and oxygen in metal-poor halo stars.

AMARSI A.M., NISSEN P.E., ASPLUND M., LIND K. and BARKLEM P.S.

Abstract (from CDS):

Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive PopulationIII stars. We reanalyse carbon, oxygen, and iron abundances in 39 metal-poor turn-off stars. For the first time, we take into account 3D hydrodynamic effects together with departures from local thermodynamic equilibrium (LTE) when determining both the stellar parameters and the elemental abundances, by deriving effective temperatures from 3D non-LTE Hβ profiles, surface gravities from Gaia parallaxes, iron abundances from 3D LTE FeII equivalent widths, and carbon and oxygen abundances from 3D non-LTE CI and OI equivalent widths. We find that [C/Fe] stays flat with [Fe/H], whereas [O/Fe] increases linearly up to 0.75dex with decreasing [Fe/H] down to -3.0dex. Therefore [C/O] monotonically decreases towards decreasing [C/H], in contrast to previous findings, mainly because the non-LTE effects for OI at low [Fe/H] are weaker with our improved calculations.

Abstract Copyright: © ESO 2019

Journal keyword(s): radiative transfer - stars: abundances - stars: late-type - stars: Population II

VizieR on-line data: <Available at CDS (J/A+A/622/L4): table1.dat table2.dat table3.dat table4.dat>

Simbad objects: 42

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2021.01.27-18:48:49

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