Global Simulations of Protoplanetary Disk Outflows with Coupled Non-ideal Magnetohydrodynamics and Consistent Thermochemistry
Global Simulations of Protoplanetary Disk Outflows with Coupled Non-ideal Magnetohydrodynamics and Consistent Thermochemistry
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DOI：
10.3847/1538-4357/ab06fd
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发表时间：
2018-10
期刊：
影响因子：
--
通讯作者：
Lile Wang;X. Bai;J. Goodman
中科院分区：
文献类型：
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作者：
Lile Wang;X. Bai;J. Goodman
磁化风在分散原行星盘和影响行星形成方面可能很重要。我们进行了轴对称的全球磁流体动力学模拟，并结合了射线追踪辐射传递、一致的热化学和非理想的MHD扩散系数。缺乏EUV光子的磁化模型具有典型极向速度的温暖分子流出。当磁化强度足以驱动吸积速率时，风的质量损失率是相当的。这种外流不是由离心驱动的，而是由弯曲极向磁场产生的环向磁场的压力驱动的。吸积和流出速率都随着极向场能量密度的增加而增加，前者几乎是线性的。质量损失率也受到风基附近紫外线和x射线辐射电离的强烈影响。在系统中加入EUV辐射可以加热、电离和加速离对称轴最近的流出部分，但通过对风基施加压力来降低总体质量损失率。我们的大多数模型都是非湍流的，但一些尘埃丰度降低，因此电离分数较高的模型在接近风底的地方表现出磁旋不稳定性。
Magnetized winds may be important in dispersing protoplanetary disks and influencing planet formation. We carry out global magnetohydrodynamic simulations in axisymmetry, coupled with ray-tracing radiative transfer, consistent thermochemistry, and non-ideal MHD diffusivities. Magnetized models lacking EUV photons ( ) feature warm molecular outflows that have typical poloidal speeds . When the magnetization is sufficient to drive accretion rates , the wind mass-loss rate is comparable. Such outflows are driven not centrifugally but by the pressure of toroidal magnetic fields produced by bending the poloidal field. Both the accretion and outflow rates increase with the poloidal field energy density, the former almost linearly. The mass-loss rate is also strongly affected by ionization due to UV and X-ray radiation near the wind base. Adding EUV irradiation to the system heats, ionizes, and accelerates the part of the outflow nearest the symmetry axis, but reduces the overall mass-loss rate by exerting pressure on the wind base. Most of our models are non-turbulent, but some with reduced dust abundance and therefore higher ionization fractions exhibit magnetorotational instabilities near the base of the wind.