论文标题
tauri星中磁层积聚的三维模拟
Three-dimensional Simulations of Magnetospheric Accretion in a T Tauri Star: Accretion and Wind Structures Just Around Star
论文作者
论文摘要
我们对托里恒星中的磁层积聚进行了三维磁流失动力学模拟，以研究恒星附近近距离的吸积和风结构。积聚在恒星上的气体由磁层边界的气体和失败的磁盘风组成。积聚气体通常是一种多柱积聚，这与观察结果一致。磁盘风的磁场和湍流的磁层内和附近的湍流磁场消除了积聚流量的角动量的很大一部分。结果，与基于质量吸积率的简单估计相比，积聚扭矩显着降低。恒星自旋通过改变磁层边界的稳定性条件来影响锥形磁盘风的时间变化。然而，时间平均磁层半径仅弱取决于恒星自旋，这与经典理论的预测不同，恒星自旋通过磁性扭矩控制磁层半径。磁层边界处的环形磁场与磁场强度的比率（这是磁性扭矩的关键参数）也对自旋不敏感。它是由磁盘动力学决定的。考虑到新发现的三维效应，我们获得了与稳定的角动量传输方程的Ghosh＆Lamb关系非常相似的磁层半径的缩放关系。
We perform three-dimensional magnetohydrodynamic simulations of magnetospheric accretion in a T Tauri star to study the accretion and wind structures in the close vicinity of the star. The gas accreting onto the star consists of the gas from the magnetospheric boundary and the failed disk winds. The accreting gas is commonly found as a multi-column accretion, which is consistent with observations. A significant fraction of the angular momentum of the accreting flows is removed by the magnetic fields of conical disk winds and turbulent failed winds inside and near the magnetosphere. As a result, the accretion torque is significantly reduced compared to the simple estimation based on the mass accretion rate. The stellar spin affects the time variability of the conical disk wind by changing the stability condition of the magnetospheric boundary. However, the time-averaged magnetospheric radius only weakly depends on the stellar spin, which is unlike the prediction of classical theories that the stellar spin controls the magnetospheric radius through the magnetic torque. The ratio of the toroidal to the poloidal field strengths at the magnetospheric boundary, which is a key parameter for the magnetic torque, is also insensitive to the spin; it is rather determined by the disk dynamics. Considering newly found three-dimensional effects, we obtain a scaling relation of the magnetospheric radius very similar to the Ghosh & Lamb relation from the steady angular momentum transport equation.
