| 中等质量恒星在赫罗图中由E-AGB星进入TP-AGB星的分界点 |
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| 引用本文： | 洪雅芳,蒋苏云.中等质量恒星在赫罗图中由E-AGB星进入TP-AGB星的分界点[J].天文学报,2011,52(4):275-287. |
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| 作者姓名： | 洪雅芳 蒋苏云 |
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| 作者单位： | 浙江师范大学数理与信息工程学院 金华 321004 |
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| 摘 要： | 通过对3～10 M_☉恒星在赫罗图上演化轨迹的研究,分析恒星内部氦壳层燃烧峰值处能量、密度、温度、氦壳层表面光度与恒星表面光度比及恒星半径的变化,给出了中等质量恒星由早期AGB星演化至热脉冲AGB星阶段在赫罗图上的分界点,与119颗碳星的观测结果吻合得相当好.同时提出:在恒星演化至该分界点之后,其星风物质损失公式可能需要引入一个与表面光度无关的量以主导超星风的形成.在此基础上,通过对考虑湍流压效应下5 M_☉恒星的结构和演化及星风物质损失率的分析,发现湍流压在热脉冲AGB星阶段对星风物质损失影响较大,从而使得热脉冲AGB星的湍流压不可忽略,进而提出了影响热脉冲AGB星星风物质损失的可能的物理因素.
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| 关 键 词： | 恒星:演化 恒星:AGB星 恒星:赫罗图 恒星:质量损失 湍流 |
The Demarcation Point from E-AGB to TP-AGB in HR Diagram for Intermediate-mass Stars |
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| HONG Ya-fang,JIANG Su-yun.The Demarcation Point from E-AGB to TP-AGB in HR Diagram for Intermediate-mass Stars[J].Acta Astronomica Sinica,2011,52(4):275-287. |
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| Authors: | HONG Ya-fang JIANG Su-yun |
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| Institution: | HONG Ya-fang JIANG Su-yun (College of Mathematics Physics and Information Technology,Zhejiang Normal University, Jinhua 321004) |
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| Abstract: | Stars with the initial masses in the range of 3≤M/M?≤10 have evolved from the main-sequence phase to the end of the asymptotic giant branch（AGB）.The evolutionary tracks in the Hertzsprung-Russel diagram（HR diagram） are investigated.The temporal variations of the energy productive rate,density and temperature at the maximum of helium burning in the helium-shell,stellar radius,and the ratio of the luminosity at the upper border of helium-shell to that of the stellar surface are analyzed.The demarcation point from E-AGB to TP-AGB in HR diagram for the intermediate-mass stars are proposed.They are in excellent agreement with the millimetric observations of 119 carbonrich giants.In order to form continuous superwind,a mass-loss function,which is unaffected by the luminosity of stellar surface after the demarcation point,is possibly necessary. Based on the above ideas,turbulent pressure has been taken into account for the mass-loss, structure and evolution of stars with masses of 5 M?.The effect of turbulent pressure cannot be overlooked in the TP-AGB phase,particularly for stellar mass-loss.Also,the possible physical factors influencing on the superwind during the TP-AGB phase are discussed. |
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| Keywords: | stars:evolution stars:AGB stars:Hertzsprung-Russell diagram stars:mass-loss turbulence |
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