Magnetic activity in late-type giant stars: Numerical MHD simulations of non-linear dynamo action in Betelgeuse
Magnetic activity in late-type giant stars: Numerical MHD simulations of non-linear dynamo action in Betelgeuse
复制标题
晚型巨星的磁活动：参宿四非线性发电机作用的数值 MHD 模拟
DOI：
10.1051/0004-6361:20040435
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发表时间：
2004
影响因子：
6.5
通讯作者：
S. Dorch
中科院分区：
文献类型：
--
作者：
S. Dorch
磁流体力学数值模拟提供了晚型巨型恒星存在磁活动的证据。一颗恒星参数与猎户座参宿四(αOrionis)相似的红色超巨星被模拟为具有高阶“铅笔代码”的“盒中之星”。线性运动学和非线性饱和发电机作用都是可能的：非线性磁场以超均分值饱和，对应于场强高达∼500Gauss的表面磁场。在线性区域中，发现了两种不同的发电机作用模式，其指数增长率分别为∼4年和25年。据推测，晚型巨星的磁活动可能会影响尘埃和风的形成，并可能导致这些恒星外部大气的加热。
Evidence is presented from numerical magneto-hydrodynamical simulations for the existence of magnetic activity in late-type giant stars. A red supergiant with stellar parameters similar to that of Betelgeuse (α Orionis) is modeled as a "star- in-a-box" with the high-order "Pencil Code". Both linear kinematic and non-linear saturated dynamo action are possible: the non-linear magnetic field saturates at a super-equipartition value corresponding to surface magnetic field of field strengths up to ∼500 Gauss. In the linear regime two different modes of dynamo action are found with exponential growth rates of ∼ 4a nd 25 years, respectively. It is speculated that magnetic activity of late-type giants may influence dust and wind formation and possibly lead to the heating of the outer atmospheres of these stars.