On the Torque Exerted by a Magnetically Threaded Accretion Disk
On the Torque Exerted by a Magnetically Threaded Accretion Disk
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DOI：
10.1086/309649
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发表时间：
1995-08
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影响因子：
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通讯作者：
Y.-M. Wang
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文献类型：
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作者：
Y.-M. Wang
对于吸积盘对旋转磁化物体（例如，可能是中子星、白矮星或金牛座T星）施加的扭矩，可以推导出简单的表达式。在平衡状态下（在恒星上没有净扭矩），开普勒盘的内缘R0非常接近旋转半径Rc，对于缠绕场分量的耗散时间的物理合理假设；“牢度参数”ω的平衡值ω临界值≡(R0/Rc)3/2在0.875 ~ 0.95之间。因此，要求ω临界值显著小于单位的经验约束与螺纹磁盘模型不相容。
Simple expressions are derived for the torque exerted by an accretion disk on a rotating, magnetized object (which may, for example, be a neutron star, a white dwarf, or a T Tauri star). In the equilibrium state (for which there is no net torque on the star), the inner edge of the Keplerian disk R0 is located very close to the corotation radius Rc, for physically plausible assumptions about the dissipation time of the wound-up field component; the equilibrium value ωcrit of the “fastness parameter” ω ≡ (R0/Rc)3/2 lies in the range 0.875-0.95. Empirical constraints requiring ωcrit to be significantly less than unity are thus incompatible with the magnetically threaded disk model.