Corotation torques experienced by planets embedded in weakly magnetized turbulent discs
Corotation torques experienced by planets embedded in weakly magnetized turbulent discs
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嵌入弱磁化湍流盘中的行星所经历的共转扭矩
DOI：
10.1051/0004-6361/201117227
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发表时间：
2011
影响因子：
6.5
通讯作者：
Baruteau C
中科院分区：
文献类型：
--
作者：
Baruteau C
低质量行星的迁移，或I型迁移，是由原行星盘的非磁性粘性模型中的差分Lindblad扭矩和共转扭矩驱动的。正转扭矩最近受到了详细的关注，因为它能够减缓、失速或逆转I型迁移。在层流粘滞盘模型中，共转力矩的长期演化与行星马蹄形区域的粘滞和热扩散过程密切相关。目前尚不清楚湍流圆盘中共转扭矩的行为，以及粘性圆盘模型是否正确预测了其振幅。目的本文旨在研究由于磁旋转不稳定性（MRI）而产生磁流体动力学（MHD）湍流的圆盘中共转扭矩的特性，考虑弱的初始环形磁场。MethodsWe目前的结果进行了两个不同的代码的三维MHD模拟。忽略非理想磁流体效应和盘的垂直分层，并考虑局部等温盘模型。运行的时间平均潮汐扭矩施加在一个固定的行星上的磁盘评估在三个不同的磁盘models.ResultsWe第一次提出模拟结果与内部盘腔（行星陷阱）。在粘性盘模型中，行星被发现经历了积极的运行时间平均扭矩超过几百个轨道，这突出了存在的不饱和的共转扭矩保持在长期的MHD湍流盘。还采用了两种具有初始幂律密度和温度分布的盘模型，其中发现时均潮汐扭矩与在行星位置具有类似粘度α参数的层流粘性盘模型中的对应物相当一致。对平均力矩密度分布的详细分析表明，MHD湍流盘和层流粘性盘的Lindblad微分力矩具有非常相似的数值，MHD湍流盘存在非饱和共转力矩。该分析还揭示了存在一个额外的共转扭矩在弱磁化discloss.ConclusionsOur结果的3D MHD模拟表明马蹄动力学和不饱和的共转扭矩在弱磁化磁盘充分发展的MHD湍流的存在。
ContextThe migration of low-mass planets, or type I migration, is driven by the differential Lindblad torque and the corotation torque in non-magnetic viscous models of protoplanetary discs. The corotation torque has recently received detailed attention, because of its ability to slow down, stall, or reverse type I migration. In laminar viscous disc models, the long-term evolution of the corotation torque is intimately related to viscous and thermal diffusion processes in the planet’s horseshoe region. It is unclear how the corotation torque behaves in turbulent discs, and whether its amplitude is correctly predicted by viscous disc models.AimsThis paper is aimed at examining the properties of the corotation torque in discs where magnetohydrodynamic (MHD) turbulence develops as a result of the magnetorotational instability (MRI), considering a weak initial toroidal magnetic field.MethodsWe present results of 3D MHD simulations carried out with two different codes. Non-ideal MHD effects and the disc’s vertical stratification are neglected, and locally isothermal disc models are considered. The running time-averaged tidal torque exerted by the disc on a fixed planet is evaluated in three different disc models.ResultsWe first present simulation results with an inner disc cavity (planet trap). As in viscous disc models, the planet is found to experience a positive running time-averaged torque over several hundred orbits, which highlights the existence of an unsaturated corotation torque maintained in the long term in MHD turbulent discs. Two disc models with initial power-law density and temperature profiles are also adopted, in which the time-averaged tidal torque is found to be in decent agreement with its counterpart in laminar viscous disc models with similar viscosity alpha parameter at the planet location. Detailed analysis of the averaged torque density distributions indicates that the differential Lindblad torque takes very similar values in MHD turbulent and laminar viscous discs, and there exists an unsaturated corotation torque in MHD turbulent discs. This analysis also reveals the existence of an additional corotation torque in weakly magnetized discs.ConclusionsOur results of 3D MHD simulations demonstrate the existence of horseshoe dynamics and an unsaturated corotation torque in weakly magnetized discs with fully developed MHD turbulence.
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DOI：
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发表时间：
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期刊：
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影响因子：
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2007
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DOI：
--
发表时间：
2009
期刊：
ApJ 701
影响因子：
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作者：
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DOI：
--
发表时间：
2006
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