Long-lived Eccentricities in Accretion Disks
Long-lived Eccentricities in Accretion Disks
复制标题
吸积盘中长期存在的偏心率
DOI：
10.3847/2041-8213/ab3a4a
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Y. Lithwick
中科院分区：
文献类型：
--
作者：
Wing;A. Dempsey;Y. Lithwick
吸积盘可以是偏心的：它们支持m = 1的模式，这种模式是全局的，缓慢的。但是这些模态是否会被困在磁盘中——并因此长久存在——取决于磁盘外缘的条件。这里我们表明，在具有现实边界的圆盘中，表面密度在给定半径之外迅速下降，偏心模式被捕获，因此可以存活与粘性时间一样长的时间。我们将重点放在中心质量周围的纯压力圆盘上，并展示如何借助简单的二阶WKB理论来理解这一结果。我们证明了寿命最长的模式是零节点模式，其中所有磁盘的椭圆流线都对齐，并且该模式在磁盘的粘性时间标度上相干衰减。因此，这种模式一旦被激发，就可以和磁盘的寿命一样长。它可能是最近原行星盘图像中不对称的原因。
Accretion disks can be eccentric: they support m = 1 modes that are global and slowly precessing. But whether the modes remain trapped in the disk—and hence are long-lived—depends on conditions at the outer edge of the disk. Here we show that in disks with realistic boundaries, in which the surface density drops rapidly beyond a given radius, eccentric modes are trapped and hence can live for as long as the viscous time. We focus on pressure-only disks around a central mass, and show how this result can be understood with the help of a simple second-order WKB theory. We show that the longest-lived mode is the zero-node mode in which all of the disk’s elliptical streamlines are aligned, and that this mode decays coherently on the viscous timescale of the disk. Hence, such a mode, once excited, could live as long as the lifetime of the disk. It may be responsible for asymmetries seen in recent images of protoplanetary disks.
影响因子：
7.9
作者：
Andrews, Sean M.;Huang, Jane;Ricci, Luca
通讯作者：
Ricci, Luca