The Effect of Combined Magnetic Geometries on Thermally Driven Winds. II. Dipolar, Quadrupolar, and Octupolar Topologies
The Effect of Combined Magnetic Geometries on Thermally Driven Winds. II. Dipolar, Quadrupolar, and Octupolar Topologies
复制标题
组合磁几何对热驱动风的影响。
DOI：
10.3847/1538-4357/aaaab5
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
S. Matt
中科院分区：
文献类型：
--
作者：
Adam J. Finley;S. Matt
在类太阳或低质量恒星的一生中，大量的角动量通过磁化的恒星风被移除。这个过程通常被认为是由磁场的偶极分量控制的。然而，观测到的磁场可能会有很强的四极和/或八极分量，这可能会影响星星上的自旋下降扭矩。在论文I中，我们使用MHD程序PLUTO计算了包含偶极和四极几何混合的恒星风的稳态解。我们表明，组合风比具有这些单独分量的风的简单总和更复杂。这项工作遵循与论文I相同的方法，包括八极几何，这不仅增加了场的复杂性，而且更重要的是，首次将相同的对称场族结合起来，偶极子和八极几何的场极性在赤道上反转（不像对称四极）。我们表明，在纸我，最低阶组件通常占主导地位的自旋扭矩。具体而言，偶极子组件是最重要的在管理的自旋扭矩的混合几何形状和在大多数条件下的真实的恒星。我们提出了一个通用的扭矩公式，其中包括复杂的，混合的字段，预测的扭矩为所有的模拟精度在20%以内，和大多数在105%以内的影响。这可以被用作旋转演化计算的输入的情况下，个别的磁性组件是已知的。
During the lifetime of Sun-like or low-mass stars a significant amount of angular momentum is removed through magnetized stellar winds. This process is often assumed to be governed by the dipolar component of the magnetic field. However, observed magnetic fields can host strong quadrupolar and/or octupolar components, which may influence the resulting spin-down torque on the star. In Paper I, we used the MHD code PLUTO to compute steady-state solutions for stellar winds containing a mixture of dipole and quadrupole geometries. We showed the combined winds to be more complex than a simple sum of winds with these individual components. This work follows the same method as Paper I, including the octupole geometry, which not only increases the field complexity but also, more fundamentally, looks for the first time at combining the same symmetry family of fields, with the field polarity of the dipole and octupole geometries reversing over the equator (unlike the symmetric quadrupole). We show, as in Paper I, that the lowest-order component typically dominates the spin-down torque. Specifically, the dipole component is the most significant in governing the spin-down torque for mixed geometries and under most conditions for real stars. We present a general torque formulation that includes the effects of complex, mixed fields, which predicts the torque for all the simulations to within 20% precision, and the majority to within ≈5%. This can be used as an input for rotational evolution calculations in cases where the individual magnetic components are known.
影响因子：
6.5
作者：
S. Saikia;S. Jeffers;J. Morin;P. Petit;P. Petit;C. Folsom;S. Marsden;J. Donati;J. Donati;R. H. Cameron;J. C. Hall;V. Perdelwitz;A. Reiners;A. Vidotto;A. Vidotto
通讯作者：
S. Saikia;S. Jeffers;J. Morin;P. Petit;P. Petit;C. Folsom;S. Marsden;J. Donati;J. Donati;R. H. Cameron;J. C. Hall;V. Perdelwitz;A. Reiners;A. Vidotto;A. Vidotto
影响因子：
20.9
作者：
A. Reiners
通讯作者：
A. Reiners
â 波江座：一颗活跃的 K 矮星和一颗拥有恒星的行星？
影响因子：
6.5
作者：
Jeffers;Marsden
通讯作者：
Marsden