Mass loss mechanisms in evolved stars
Mass loss mechanisms in evolved stars
复制标题
演化恒星的质量损失机制
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
N. Berruyer
中科院分区：
文献类型：
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作者：
J. Lafon;N. Berruyer
质量损失是恒星演化中一个非常重要的现象。在恒星的晚期，它变得相当高(高达10−4M⊙/年)，但膨胀速度大大降低(约30 Kms−1)。它也可以是可变的，零星的。现在，虽然第一个冷恒星质量损失的观测证据通常被归因于1935年的亚当斯和麦考马克，而且自这一发现以来，尽管许多观测和理论论文都致力于此，但我们只知道在主导物理条件下可能有效的机制，但没有一个机制或机制的组合能够产生观察到的效果。最常被引用的(热气体压力、辐射压力、声波、冲击波、阿尔芬波、⋯)将被描述和批评，重点是至少在冷大气外部工作的尘埃颗粒的辐射压力。还讨论了膨胀大气的几何形状和内容，以及在小尺度上可能重要的机制。理论和观察都被考虑在内。
SummaryMass loss is a very important phenomenon for stellar evolution. In the late stages of stars it becomes fairly high (up to 10−4 M⊙/yr) though with a much decreased expansion velocity (about 30 kms−1). It can also be variable, sporadic. Now, though the first observational evidence for mass loss from cool stars is usually attributed to Adams and McCormak in 1935 and though a lot of observational and theoretical papers have been devoted to it since this discovery, we only know mechanisms which are probably efficient under the dominant physical conditions, but neither one mechanism nor a combination of mechanisms is able to produce the observed effects. Those most invoked (thermal gas pressure, radiation pressure, acoustic waves, shock waves, Alfvén waves, ⋯) will be described and criticized, with emphasis on the radiation pressure on dust grains at work at least in the outer part of cool atmospheres. The geometry and the content of expanding atmospheres are also discussed together with the mechanisms that may be important at small scales. Both theory and observations are taken into accout.