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arXiv · 1612.01622

Ages of 70 dwarfs of three populations in the solar neighborhood: considering O and C abundances in stellar models

Z. S. Ge·S. L. Bi·Y. Q. Chen·T. D. Li·J. K. Zhao·K. Liu·Fergusion J. W.·Y. Q. Wu
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Abstract

Oxygen and carbon are important elements in stellar populations. Their behavior refers to the formation history of the stellar populations. C and O abundances would also obviously influence stellar opacities and the overall metal abundance $Z$. With observed high-quality spectroscopic properties, we construct stellar models with C and O elements, to give more accurate ages for 70 metal-poor dwarfs, which have been determined to be high-$α$ halo, low-$α$ halo and thick-disk stars. Our results show that high-$α$ halo stars are relatively older than low-$α$ halo stars by around 2.0 Gyr. The thick-disk population has an age range between the two halo populations. The age distribution profiles indicate that high-$α$ halo and low-$α$ halo stars match the in situ accretion simulation by Zolotov et al., and the thick-disk stars might be formed in a relatively quiescent and long-lasting process. We also note that stellar ages are very sensitive to O abundance, since the ages clearly increase with increasing [O/Fe] values. Additionally, we obtain several stars with peculiar ages, including 2 young thick-disk stars and 12 stars older than the universe age.

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Z. S. Ge, S. L. Bi, Y. Q. Chen, T. D. Li, J. K. Zhao, K. Liu, Fergusion J. W., Y. Q. Wu. 2016-12-06. Ages of 70 dwarfs of three populations in the solar neighborhood: considering O and C abundances in stellar models. https://doi.org/10.3847/1538-4357%2F833%2F2%2F161

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