大质量不平衡转捩盘的气体和尘埃流体动力学模拟-I。气体分配
Gas and dust hydrodynamical simulations of massive lopsided transition discs - I. Gas distribution
摘要：
基于在一些大质量过渡盘中观测到的不平衡结构，我们对大质量盘中的涡旋结构进行了二维数值模拟，包括盘的自引力效应和不平衡结构引起的中心恒星偏离系统重心的间接力.当只包括间接力时，我们证实了Mittal & Chiang（2015）的发现，即只要盘星质量比> 1%，涡旋就会变得更强，并且可以超过两个压力标度高度。这样宽的涡旋可以在圆盘中激发出强烈的密度波，从而迅速向内迁移。然而，当在模拟中也考虑圆盘自重力时，自重力对涡结构起着更突出的作用。我们证实，当盘Toomre Q参数小于pi/（2h），其中h是盘的纵横比，涡显着减弱，其向内迁移显着减慢。最重要的是，当盘的质量足够大（例如Q~3）时，我们发现不平衡气体结构以明显低于局部开普勒速度的速度绕恒星运行。这种次开普勒模式的速度可以导致尘埃粒子的浓度在半径超过不平衡的气体结构（如论文II所示）。总的来说，光盘自重调节大规模光盘和大规模光盘内的气体和尘埃分布的旋涡之间的径向位移的旋涡结构可能会被探测到未来的观测。
英文摘要：
Motivated by lopsided structures observed in some massive transition discs, we have carried out 2D numerical simulations to study vortex structure in massive discs, including the effects of disc self-gravity and the indirect force which is due to the displacement of the central star from the barycenter of the system by the lopsided structure. When only the indirect force is included, we confirm the finding by Mittal & Chiang (2015) that the vortex becomes stronger and can be more than two pressure scale heights wide, as long as the disc-to-star mass ratio is >1%. Such wide vortices can excite strong density waves in the disc and therefore migrate inwards rapidly. However, when disc self-gravity is also considered in simulations, self-gravity plays a more prominent role on the vortex structure. We confirm that when the disc Toomre Q parameter is smaller than pi/(2h), where h is the disc's aspect ratio, the vortices are significantly weakened and their inward migration slows down dramatically. Most importantly, when the disc is massive enough (e.g. Q~3), we find that the lopsided gas structure orbits around the star at a speed significantly slower than the local Keplerian speed. This sub-Keplerian pattern speed can lead to the concentration of dust particles at a radius beyond the lopsided gas structure (as shown in Paper II). Overall, disc self-gravity regulates the vortex structure in massive discs and the radial shift between the gas and dust distributions in vortices within massive discs may be probed by future observations.
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