磁激励线驱动恒星风的动力学模拟：II。场向旋转效应
Dynamical Simulations of Magnetically Channeled Line-Driven Stellar Winds: II. The Effects of Field-Aligned Rotation
摘要：
建立在我们以前的磁流体模拟研究磁沟道辐射驱动恒星风，我们在这里研究恒星{\em旋转}的额外动力学效应在（仍然）2-D轴对称的情况下，一个对齐的偶极子表面场。除了磁约束参数$η_{\ast}$介绍了在纸我，我们的特点的恒星旋转的参数$W \equiv V_{\rm{rot}}/V_{\rm{orb}}$（赤道表面的旋转速度轨道速度的比率），检查具体的模型与中等强旋转$W =$ 0.25和0.5，并比较这些类似的非旋转的情况。定义了相关的阿尔文半径$R_{\rm{A}} \approx η_{\ast}^{1/4} \Rstar$和开普勒共转半径$R_{\rm{K}} \approx W^{-2/3} \Rstar$，我们发现旋转效应对于具有$R_{\rm{A}} < R_{\rm{K}}$的模型是弱的，但是对于具有$R_{\rm{A}} \gtwig R_{\rm{K}}$的模型可以是显著的，甚至是主导的。特别是，通过扩展我们的模拟磁约束参数（最高可达$η_{\ast} = 1000$）远高于（$η_{\ast} = 10$）在论文I中考虑，我们能够使用$R_{\rm{A}} \gg R_{\rm{K}}$研究案例;我们发现，这些确实显示了在以前的分析模型中预测的{PDMATHAMM刚体}盘的清晰形成，然而，以限制盘体质量积累的向下下沉和向外爆发两个事件为特征的动力学行为。总的来说，结果提供了一个有趣的一瞥旋转和磁约束之间的复杂的相互作用，并形成了一个完整的MHD描述的刚性体磁盘的基础，预计在强磁性Bp恒星，如$σ$ Ori E。
英文摘要：
Building upon our previous MHD simulation study of magnetic channeling in radiatively driven stellar winds, we examine here the additional dynamical effects of stellar {\em rotation} in the (still) 2-D axisymmetric case of an aligned dipole surface field. In addition to the magnetic confinement parameter $η_{\ast}$ introduced in Paper I, we characterize the stellar rotation in terms of a parameter $W \equiv V_{\rm{rot}}/V_{\rm{orb}}$ (the ratio of the equatorial surface rotation speed to orbital speed), examining specifically models with moderately strong rotation $W =$ 0.25 and 0.5, and comparing these to analogous non-rotating cases. Defining the associated Alfvén radius $R_{\rm{A}} \approx η_{\ast}^{1/4} \Rstar$ and Kepler corotation radius $R_{\rm{K}} \approx W^{-2/3} \Rstar$, we find rotation effects are weak for models with $R_{\rm{A}} < R_{\rm{K}}$, but can be substantial and even dominant for models with $R_{\rm{A}} \gtwig R_{\rm{K}}$. In particular, by extending our simulations to magnetic confinement parameters (up to $η_{\ast} = 1000$) that are well above those ($η_{\ast} = 10$) considered in Paper I, we are able to study cases with $R_{\rm{A}} \gg R_{\rm{K}}$; we find that these do indeed show clear formation of the {\em rigid-body} disk predicted in previous analytic models, with however a rather complex, dynamic behavior characterized by both episodes of downward infall and outward breakout that limit the buildup of disk mass. Overall, the results provide an intriguing glimpse into the complex interplay between rotation and magnetic confinement, and form the basis for a full MHD description of the rigid-body disks expected in strongly magnetic Bp stars like $σ$ Ori E.
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