Origin of complex non-axisymmetric structures in Type 2 Transition Disks

阿塔卡马大型毫米波阵列的巨大分辨率和灵敏度揭示了原行星盘在高角分辨率下的样子。一幅图像正在浮现，大多数磁盘在很大程度上是轴对称的，并且通常具有很强的径向（多环状）结构。这些环的起源尚不清楚，但也不是完全出乎意料：由于开普勒定律的不同旋转性质，圆盘上的任何不均匀性都必然会在方面角上被涂抹成环。此外，任何出现在圆盘上的行星都会倾向于在圆盘上打开一个环形的缺口。因此，真正令人惊讶的是，在目前用ALMA进行的高分辨率调查中，大约5- 15%的圆盘显示出非轴对称特征。这些包括$m=2$螺旋，奇怪的尘埃弧，以及内盘相对于外盘倾斜的盘翘曲。这些非轴对称特征必须与足够强大的力有关，这些力可以与微分开普勒旋转的“涂抹”性质相竞争。换句话说，这些特征表明，在这些圆盘中发生的事情超出了标准的原行星盘物理学。这可能是一颗年轻行星的存在，尘埃捕获漩涡的存在，不稳定的作用，或许多其他过程。了解它们是一个独特的机会，可以通过观测来了解行星形成的过程。该项目的目标是测试一系列场景，包括那些根植于行星形成的场景，以解释观察到的非轴对称特征，并破译隐藏在这些特征中的信息，从而提高我们对行星形成的理解。

The enormous resolving power and sensitivity of the Atacama Large Millimeter Array has revealed what protoplanetary disks look like at high angular resolution. A picture is emerging that most disks are to a large extent axially symmetric, and generally have strong radial (multi-ringlike) structure. The origin of these rings is not yet understood, but it is also not quite unexpected: due to the differentially rotating nature of Kepler's law, any inhomogeneity in the disk is bound to be azimuthally smeared out into a ring. Moreover, any planet present in the disk will tend to open an annular gap in the disk. So the real surprise is that in the current high resolution surveys with ALMA about 5-15\% of the disks show non-axisymmetric features. These include $m=2$ spirals, strange dusty arcs, as well as disk warps where the inner disk is inclined with respect to the outer disk. These non-axially symmetric features must be related to forces that are strong enough that they can compete with the ``smearing out'' nature of differential keplerian rotation. In other words: These features are an indication that something is going on in these disks that goes beyond the standard protoplanetary disk physics. This could be the presence of a young planet, the presence of a dust-trapping vortex, the action of an instability, or a number of other processes. Learning about them is a unique chance at gathering observational insight into the process of planet formation. The goal of this project is to test a range of scenarios, including those that are rooted in planet formation, for the explanation of the observed non-axisymmetric features, and to decypher the message that is hidden in these features and hence improve our understanding of planet formation.