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首页> 外文期刊>The Astrophysical journal >HALL EFFECT CONTROLLED GAS DYNAMICS IN PROTOPLANETARY DISKS. II. FULL 3D SIMULATIONS TOWARD THE OUTER DISK
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HALL EFFECT CONTROLLED GAS DYNAMICS IN PROTOPLANETARY DISKS. II. FULL 3D SIMULATIONS TOWARD THE OUTER DISK

机译:霍尔效应控制着原代盘中的气体动力学。二。面向外盘的完整3D模拟

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摘要

We perform three-dimensional stratified shearing-box magnetohydrodynamic (MHD) simulations on the gas dynamics of protoplanetary disks with a net vertical magnetic flux of B z0. All three nonideal MHD effects, Ohmic resistivity, the Hall effect, and ambipolar diffusion, are included in a self-consistent manner based on equilibrium chemistry. We focus on regions toward outer disk radii, from 5 to 60?AU, where Ohmic resistivity tends to become negligible, ambipolar diffusion dominates over an extended region across the disk height, and the Hall effect largely controls the dynamics near the disk midplane. We find that at around R = 5?AU the system launches a laminar or weakly turbulent magnetocentrifugal wind when the net vertical field B z0 is not too weak. Moreover, the wind is able to achieve and maintain a configuration with reflection symmetry at the disk midplane. The case with anti-aligned field polarity () is more susceptible to the magnetorotational instability (MRI) when B z0 decreases, leading to an outflow oscillating in radial directions and very inefficient angular momentum transport. At the outer disk around and beyond R = 30?AU, the system shows vigorous MRI turbulence in the surface layer due to far-UV ionization, which efficiently drives disk accretion. The Hall effect affects the stability of the midplane region to the MRI, leading to strong/weak Maxwell stress for aligned/anti-aligned field polarities. Nevertheless, the midplane region is only very weakly turbulent in both cases. Overall, the basic picture is analogous to the conventional layered accretion scenario applied to the outer disk. In addition, we find that the vertical magnetic flux is strongly concentrated into thin, azimuthally extended shells in most of our simulations beyond 15?AU, leading to enhanced radial density variations know as zonal flows. Theoretical implications and observational consequences are briefly discussed.
机译:我们对净垂直磁通量为B z0的原行星盘的气体动力学进行三维分层剪切盒磁流体动力学(MHD)模拟。基于平衡化学,以自洽的方式包括所有三个非理想的MHD效应,欧姆电阻率,霍尔效应和双极性扩散。我们将重点放在朝外圆盘半径(从5至60?AU)的区域,在该区域中,欧姆电阻率趋于可忽略不计,双极扩散在整个圆盘高度的扩展区域中占主导地位,霍尔效应在很大程度上控制了圆盘中平面附近的动力学。我们发现,当净垂直场B z0不太弱时,系统会在R = 5?AU附近发射层流或弱湍流的磁离心风。而且,风能够在磁盘中平面处实现并维持具有反射对称性的构造。当B z0减小时,具有反磁场极性()的情况更容易受到磁旋转不稳定性(MRI)的影响,从而导致沿径向振荡的流出和效率极低的角动量传输。在远处的R = 30?AU附近的外盘上,由于远紫外电离,该系统在表层显示出剧烈的MRI湍流,从而有效地驱动了盘的积聚。霍尔效应影响MRI的中平面区域的稳定性,从而导致对准/反对准场极性的麦克斯韦应力强/弱。然而,在两种情况下,中平面区域仅是非常弱的湍流。总体而言,基本情况类似于应用于外磁盘的常规分层堆积方案。此外,我们发现在大多数模拟中,垂直磁通量都强烈集中在超过15?AU的薄的,方位角延伸的壳中,从而导致径向密度变化(称为纬向流)增加。简要讨论了理论含义和观察结果。

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