LOW-MASS PLANETS IN PROTOPLANETARY DISKS WITH NET VERTICAL MAGNETIC FIELDS: THE PLANETARY WAKE AND GAP OPENING
LOW-MASS PLANETS IN PROTOPLANETARY DISKS WITH NET VERTICAL MAGNETIC FIELDS: THE PLANETARY WAKE AND GAP OPENING
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具有净垂直磁场的原行星盘中的低质量行星：行星尾流和间隙张开
DOI：
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
R. Rafikov
中科院分区：
文献类型：
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作者：
Zhaohuan Zhu;J. Stone;R. Rafikov
原行星盘中的某些区域是湍流的，而某些区域是静止的（例如死区）。为了研究行星如何在无粘流体动力盘（例如死区）和受磁旋转不稳定性（MRI）影响的盘中打开间隙，我们进行了剪切盒二维无粘流体动力模拟和三维非分层磁流体动力（MHD）模拟（具有净垂直磁场），行星位于盒中心。我们发现，由于非线性波陡化，即使是低质量行星在这两种情况下也可以打开间隙，这与间隙打开的“热标准”相矛盾。为了了解我们是否可以用粘性 α 处方来表示 MRI 湍流应力来研究间隙张开，我们将 MRI 湍流盘中的间隙特性与具有相同应力的粘性 HD 盘中的间隙特性进行比较，发现相同质量的行星在净垂直通量 MHD 盘中打开的间隙比在粘性 HD 盘中明显更深、更宽。这种差异的产生是由于磁场有效传输到 MRI 磁盘的间隙区域，导致间隙内产生更大的有效 α。因此，在整个间隙中，麦克斯韦应力分布比间隙密度分布更平滑，并且麦克斯韦应力梯度需要更深的间隙来平衡行星扭矩密度。与之前的净环形磁通/零磁通 MHD 模拟结果进行比较表明，磁场几何形状在间隙打开过程中起着重要作用。我们还发现 MRI 产生的长期密度特征（称为纬向流）可以影响行星迁移。总的来说，我们的结果表明，间隙通常是由现实原行星盘中的低质量行星产生的，并警告使用恒定的 α 粘度来模拟原行星盘中的间隙。
Some regions in protoplanetary disks are turbulent, while some regions are quiescent (e.g. the dead zone). In order to study how planets open gaps in both inviscid hydrodynamic disk (e.g. the dead zone) and the disk subject to magnetorotational instability (MRI), we carried out both shearing box two-dimensional inviscid hydrodynamical simulations and three-dimensional unstratified magnetohydrodynamical (MHD) simulations (having net vertical magnetic fields) with a planet at the box center. We found that, due to the nonlinear wave steepening, even a low mass planet can open gaps in both cases, in contradiction to the “thermal criterion” for gap opening. In order to understand if we can represent the MRI turbulent stress with the viscous α prescription for studying gap opening, we compare gap properties in MRI-turbulent disks to those in viscous HD disks having the same stress, and found that the same mass planet opens a significantly deeper and wider gap in net vertical flux MHD disks than in viscous HD disks. This difference arises due to the efficient magnetic field transport into the gap region in MRI disks, leading to a larger effective α within the gap. Thus, across the gap, the Maxwell stress profile is smoother than the gap density profile, and a deeper gap is needed for the Maxwell stress gradient to balance the planetary torque density. Comparison with previous results from net toroidal flux/zero flux MHD simulations indicates that the magnetic field geometry plays an important role in the gap opening process. We also found that long-lived density features (termed zonal flows) produced by the MRI can affect planet migration. Overall, our results suggest that gaps can be commonly produced by low mass planets in realistic protoplanetary disks, and caution the use of a constant α-viscosity to model gaps in protoplanetary disks.
DOI：
10.1146/annurev-astro-081811-125523
发表时间：
2012-03
影响因子：
33.3
作者：
W. Kley;R. Nelson
通讯作者：
W. Kley;R. Nelson
嵌入弱磁化湍流盘中的行星所经历的共转扭矩
影响因子：
6.5
作者：
Baruteau C
通讯作者：
Baruteau C