中国物理B ›› 2008, Vol. 17 ›› Issue (4): 1518-1525.doi: 10.1088/1674-1056/17/4/061

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The lack of carbon stars in the Galactic bulge

吕国梁1, 王兆军1, 张军1, 朱春花2   

  1. (1)Department of Physics, Xinjiang University, Wulumuqi 830046, China; (2)School of Science, Xi'an Jiaotong University, Xi'an 710049, China；Department of Physics, Xinjiang University, Wulumuqi 830046, China
  • 收稿日期:2007-08-29 修回日期:2007-12-03 出版日期:2008-04-20 发布日期:2008-04-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10647003), and the Foundations of Xinjiang University, China (Grant Nos 070195 and BS060109).

The lack of carbon stars in the Galactic bulge

Zhu Chun-Hua(朱春花)a)b), LüGuo-Liang(吕国梁)b), Wang Zhao-Jun(王兆军)b), and Zhang Jun(张军)b)†   

  1. a School of Science, Xi'an Jiaotong University, Xi'an 710049, China; b Department of Physics, Xinjiang University, Wulumuqi 830046, China
  • Received:2007-08-29 Revised:2007-12-03 Online:2008-04-20 Published:2008-04-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10647003), and the Foundations of Xinjiang University, China (Grant Nos 070195 and BS060109).

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摘要： In order to explain the lack of carbon stars in the Galactic bulge, we have made a detailed study of thermal pulse-asymptotic giant branch (TP-AGB) stars by using a population synthesis code. The effects of the oxygen overabundance and the mass loss rate on the ratio of the number of carbon stars to that of oxygen stars in the Galactic bulge are discussed. We find that the oxygen overabundance which is about twice as large as that in the solar neighbourhood (close to the present observations) is insufficient to explain the rareness of carbon stars in the bulge. We suggest that the large mass loss rate may serve as a controlling factor in the ratio of the number of carbon stars to that of oxygen stars.

关键词: carbon stars, thermal pulse-asymptotic giant branch (TP-AGB), population synthesis, Galactic bulge

Abstract: In order to explain the lack of carbon stars in the Galactic bulge, we have made a detailed study of thermal pulse-asymptotic giant branch (TP-AGB) stars by using a population synthesis code. The effects of the oxygen overabundance and the mass loss rate on the ratio of the number of carbon stars to that of oxygen stars in the Galactic bulge are discussed. We find that the oxygen overabundance which is about twice as large as that in the solar neighbourhood (close to the present observations) is insufficient to explain the rareness of carbon stars in the bulge. We suggest that the large mass loss rate may serve as a controlling factor in the ratio of the number of carbon stars to that of oxygen stars.

Key words: carbon stars, thermal pulse-asymptotic giant branch (TP-AGB), population synthesis, Galactic bulge

中图分类号:  (Main-sequence: late-type stars (G, K, and M))

  • 97.20.Jg
97.20.Li (Giant and subgiant stars)