AGES OF 70 DWARFS OF THREE POPULATIONS IN THE SOLAR NEIGHBORHOOD: CONSIDERING O AND C ABUNDANCES IN STELLAR MODELS
- Department of Astronomy, Beijing Normal University, Beijing 100875 (China)
- Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
- Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia)
- Department of Physics, Wichita State University, Wichita, KS 67260-0032 (United States)
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 somewhat older than low- α halo stars by around 2.0 Gyr. The thick-disk population has an age range in 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.
- OSTI ID:
- 22661327
- Journal Information:
- Astrophysical Journal, Vol. 833, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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