标题： 原行星盘的多波长观测作为气体盘质量的替代指标 显示英文标题

标题： Multi-wavelength observations of protoplanetary discs as a proxy for the gas disc mass

摘要： 近期对原行星盘的观测揭示了可能由嵌入行星引起的盘亚结构。 我们研究了盘中的气体表面密度如何改变散射光和尘埃连续辐射的观测形态。 假设盘亚结构是由嵌入的原行星引起的，我们将流体力学建模与带有行星的尘埃原行星盘的辐射传输模拟相结合。 不同尘埃种类对行星诱导的引力扰动的响应取决于拖曳停止时间——这是局部气体密度（通常未知）的函数。 小尘粒被气体束缚，显示出螺旋状结构。 较大的颗粒则会解耦，随着颗粒大小增加或气体盘质量的减少，显示出越来越轴对称（环状）的亚结构。 我们证明，同时对散射光和尘埃连续辐射进行建模能够限制施托克斯数，${\rm St}$。 因此，如果已知尘埃特性，则可以限制该结构位置处的局部气体表面密度，$\Sigma_{\rm gas}$，从而约束总气体质量。 特别是，我们发现观察毫米波发射颗粒的环状结构需要${\rm St} \gtrsim 0.4$因此需要$\Sigma_{\rm gas} \lesssim 0.4\,\textrm{g/cm}^{2}$。 我们将这一想法应用于显示散射光和尘埃连续辐射中亚结构的观测原行星盘。 显示英文摘要

摘要： Recent observations of protoplanetary discs reveal disc substructures potentially caused by embedded planets. We investigate how the gas surface density in discs changes the observed morphology in scattered light and dust continuum emission. Assuming that disc substructures are due to embedded protoplanets, we combine hydrodynamical modelling with radiative transfer simulations of dusty protoplanetary discs hosting planets. The response of different dust species to the gravitational perturbation induced by a planet depends on the drag stopping time - a function of the generally unknown local gas density. Small dust grains, being stuck to the gas, show spirals. Larger grains decouple, showing progressively more axisymmetric (ring-like) substructure as decoupling increases with grain size or with the inverse of the gas disc mass. We show that simultaneous modelling of scattered light and dust continuum emission is able to constrain the Stokes number, ${\rm St}$. Hence, if the dust properties are known, this constrains the local gas surface density, $\Sigma_{\rm gas}$, at the location of the structure, and hence the total gas mass. In particular, we found that observing ring-like structures in mm-emitting grains requires ${\rm St} \gtrsim 0.4$ and therefore $\Sigma_{\rm gas} \lesssim 0.4\,\textrm{g/cm}^{2}$. We apply this idea to observed protoplanetary discs showing substructures both in scattered light and in the dust continuum.