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- Yoichi Takeda
- 1Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-8588 E-mail (YT): takedayi@cc.nao.ac.jp
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- Masahide Takada-Hidai
- 2Research Institute of Civilization, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-12
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説明
<jats:p>The abundances of carbon and helium were determined for representative late-B and early-A supergiants based on the CI lines (9078, 9089, 9095, 9112) in the near-IR, CII lines (4267, 6151), and the He I 6678 line, in an aim to investigate the nature of the envelope-mixing in these evolved stars based on the anomaly (if any) of these elements combined with that of N and O published before. It turned out that N tends to increase with a decrease in C, showing a tendency of conserving the sum of C+N nuclei, which suggests that the anomaly of C and N may be reasonably interpreted as being due to mixing of the CN-processed material. However, this increase/decrease in N/C, indicative of dredge-up of the H-burning product, is not accompanied by any He-enrichment. Even surprisingly, the observed tendency is just the opposite, i.e., [He/H] appears to decrease progressively in accordance with a lowering of [C/H]. Instead of regarding this apparent characteristics as being real, we tentatively speculate that some activity-related line-weakening mechanism (e.g., irradiance of X-rays) might act on the formation of He I lines, the extent of which is indirectly related to the efficiency of envelope mixing via stellar rotation.</jats:p>
収録刊行物
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- Publications of the Astronomical Society of Japan
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Publications of the Astronomical Society of Japan 52 (1), 113-125, 2000-02-01
Oxford University Press (OUP)
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詳細情報 詳細情報について
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- CRID
- 1360011144309335168
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- ISSN
- 2053051X
- 00046264
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- データソース種別
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- Crossref
- OpenAIRE