Chemical mixing by turbulent convection in the overshooting region below the convective envelope of RGB stars
文献类型：期刊论文
| 作者 | Lai XJ(赖祥军)1,2,3 ; Li Y(李焱)1,2
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| 刊名 | RESEARCH IN ASTRONOMY AND ASTROPHYSICS
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| 出版日期 | 2011-11 |
| 卷号 | 11期号:11页码:1351-1370 |
| 关键词 | stars: convection stars: interiors stars: HR diagram-blue loops-Cepheids Galactic open clusters |
| ISSN号 | 1674-4527 |
| 产权排序 | 第一完成单位 |
| 通讯作者 | Lai, XJ (reprint author), Chinese Acad Sci, Yunnan Observ, Natl Astron Observ, Kunming 650011, Peoples R China. |
| 英文摘要 | Based on the turbulent convection model (TCM), we investigate chemical mixing in the bottom overshooting region of the convective envelope of intermediate-mass stars, focusing on its influence on the formation and extension of blue loops in the Hertzsprung-Russell (HR) diagram. A diffusive mixing model is adopted during the Red Giant Branch (RGB) phase. The properties of the blue loop are changed by modification of the element profiles above the H-burning shell, which results from the incomplete mixing in the bottom overshooting region when the stellar model evolves up along the RGB. Such modification of the element profiles will lead to an increase of opacity in the region just above the H-burning shell and a decrease of opacity in the outer homogeneous convection zone, which will result in a quick decrease of the H-shell nuclear luminosity L-H when the stellar model evolves from the RGB tip to its bottom and, finally, a much weaker and smaller convection zone will be obtained in the stellar envelope. This helps to form a longer blue loop. The extension of the blue loop is very sensitive to the parameters (C-X and alpha(TCM)) of the diffusive mixing model and of the TCM. The results mainly show that: 1) comparing the results of the classical model with the mixing-length theory, the lengths of the obtained blue loops with different combinations of the values of C-X and alpha(TCM) are all increased and the length of the blue loop increases with the values of parameters C-X and alpha(TCM); 2) the diffusive mixing model can significantly extend the time of stellar models lingering on the blue side of the HR diagram, even though the length of the blue loop for the 7M(circle dot) star has a less prominent difference between the classical and diffusive mixing model; 3) both the observations referring to the location of the Cepheid instability strip and the number ratio N-B/N-R of blue to red evolved stars in the Galactic open clusters can confine the two parameters in a range of 0.5 <= alpha(TCM) <= 0.9 and 10(-5) <= C-X <= 10(-4) for the model of 5M(circle dot). However, for the case of the 7M(circle dot) star, there seems to be no such definite range to even only account for the observed number ratio N-B/N-R. In any case, our results based on the diffusive mixing model are on the whole in accordance with not only other theoretical ones but also the observations. |
| WOS标题词 | Science & Technology ; Physical Sciences |
| 学科主题 | Astronomy & Astrophysics |
| 类目[WOS] | Astronomy & Astrophysics |
| 研究领域[WOS] | Astronomy & Astrophysics |
| 关键词[WOS] | INTERMEDIATE-MASS STARS ; RED SUPERGIANT RATIO ; BLUE-TO-RED ; STELLAR EVOLUTION ; CLASSICAL CEPHEIDS ; AGB STARS ; ASTROPHYSICAL APPLICATIONS ; DYNAMICAL EVOLUTION ; OBSERVATIONAL TESTS ; INSTABILITY STRIP |
| 收录类别 | SCI |
| 原文出处 | http://iopscience.iop.org/article/10.1088/1674-4527/11/11/010/meta |
| 语种 | 英语 |
| WOS记录号 | WOS:000297441300010 |
| 源URL | [http://ir.ynao.ac.cn/handle/114a53/5205]  |
| 专题 | 云南天文台_恒星物理研究组 云南天文台_中国科学院天体结构与演化重点实验室 |
| 作者单位 | 1.National Astronomical Observatories / Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011, China 2.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650011, China 3.Graduate University of Chinese Academy of Sciences, Beijing 100049, China |
| 推荐引用方式 GB/T 7714 | Lai XJ,Li Y. Chemical mixing by turbulent convection in the overshooting region below the convective envelope of RGB stars[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2011,11(11):1351-1370. |
| APA | Lai XJ,&Li Y.(2011).Chemical mixing by turbulent convection in the overshooting region below the convective envelope of RGB stars.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,11(11),1351-1370. |
| MLA | Lai XJ,et al."Chemical mixing by turbulent convection in the overshooting region below the convective envelope of RGB stars".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 11.11(2011):1351-1370. |
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来源：云南天文台
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