论文标题
年轻恒星磁化积聚磁盘的动力学
Dynamics of magnetized accretion disks of young stars
论文作者
论文摘要
我们研究了具有化石大规模磁场的年轻恒星积聚盘的动力学。作者的积聚磁盘的磁性水力动力学（MHD）模型被推广，以考虑磁场对气体旋转速度和磁盘垂直结构的动态影响。在开发的MHD模型的帮助下，模拟了太阳能质量tauri星的积聚盘的结构，以不同的吸积率$ \ dot {m} $和灰尘粒度$ a_d $。磁盘的径向结构的模拟表明，磁盘中的磁场是运动的，电磁力不会影响气体的旋转速度$ \ dot {m} = 10^{ - 8} \，m_ \ odot \ odot \ odot \，\ odot \，\ mbox \，\ mbox {yr} {yr}^^$a________________。就大尘谷物而言，$ a_d \ geq 1 $毫米，磁场被冷冻到气体中，并在距离星形$ r \ gtrsim 30 $ 30 $ au的径向距离时产生了动态强的磁场，其紧张速度将旋转速度降低了$ \ \\ $ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ $ \ \ \ \ \ \ \ \ \ \ \ \\ $ \ \ \ \ \ \\ $ \ \ \ \ \ \\ $ \ \ \ \\ $ \ \\ $ \ $ \ applerian velocity velocity velocity velocity的1.5 $％。这种作用与气压的径向梯度的贡献相当，并且可能导致吸积盘中尘埃晶粒的径向漂移速度的增加。在高积聚率的情况下，$ \ dot {m} \ geq 10^{ - 7} \，m_ \ odot \，\ mbox {yr}^{ - 1} $，磁场在磁盘的内部区域也动态强，$ r <0.2 $ au。磁盘的垂直结构的模拟表明，根据磁盘表面的条件，磁性压力的垂直梯度可以导致磁盘的特征厚度减小和增加，而静水压音高为5-20％。磁盘厚度的变化发生在低电离馏分和有效磁扩散区域（“死亡”区域）之外，该区域从$ r = 0.3 $延伸至典型参数的$ 20 $ au。
We investigate the dynamics of the accretion disks of young stars with fossil large-scale magnetic field. The author's magnetohydrodynamic (MHD) model of the accretion disks is generalized to consider the dynamical influence of the magnetic field on gas rotation speed and vertical structure of the disks. With the help of the developed MHD model, the structure of an accretion disk of a solar mass T Tauri star is simulated for different accretion rates $\dot{M}$ and dust grain sizes $a_d$. The simulations of the radial structure of the disk show that the magnetic field in the disk is kinematic, and the electromagnetic force does not affect the rotation speed of the gas for typical values $\dot{M}=10^{-8}\,M_\odot\,\mbox{yr}^{-1}$ and $a_d=0.1 μ$m. In the case of large dust grains, $a_d\geq 1$ mm, the magnetic field is frozen into the gas and a dynamically strong magnetic field is generated at radial distances from the star $r\gtrsim 30$ au, the tensions of which slow down the rotation speed by $\lesssim 1.5$ % of the Keplerian velocity. This effect is comparable to the contribution of the radial gradient of gas pressure and can lead to the increase in the radial drift velocity of dust grains in the accretion disks. In the case of high accretion rate, $\dot{M}\geq 10^{-7}\,M_\odot\,\mbox{yr}^{-1}$, the magnetic field is also dynamically strong in the inner region of the disk, $r<0.2$ au. The simulations of the vertical structure of the disk show that, depending on the conditions on the surface of the disk, the vertical gradient of magnetic pressure can lead to both decrease and increase in the characteristic thickness of the disk as compared to the hydrostatic one by 5-20 %. The change in the thickness of the disk occurs outside the region of low ionization fraction and effective magnetic diffusion (`dead' zone), which extends from $r=0.3$ to $20$ au at typical parameters.
