分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： As one of the most commonly observed disk substructures, dust rings from high-resolution disk surveys appear to have different radial widths. Recent observations on PDS 70 and AB Aur reveal not only planets in the disk, but also the accompanying wide dust rings. We use three-dimensional dust-and-gas disk simulations to study whether gap-opening planets are responsible for the large ring width in disk observations. We find that gap-opening planets can widen rings of dust trapped at the pressure bump via planetary perturbations, even with the mid-plane dust-to-gas ratio approaching order unity and with the dust back-reaction accounted for. We show that the planet-related widening effect of dust rings can be quantified using diffusion-advection theory, and provide a generalized criterion for an equilibrated dust ring width in three-dimensional disk models. We also suggest that the ring width can be estimated using the gas turbulent viscosity $\alpha_{\rm turb}$, but with cautions about the Schmidt number greater than order unity.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The role of radiation pressure in dust migration and the opening of inner cavities in transitional disks is revisited in this paper. Dust dynamics including radiation pressure is often studied in axisymmetric models, but in this work, we show that highly non-axisymmetric features can arise from an instability at the inner disk edge. Dust grains clump into high density features there, allowing radiation to leak around them and penetrate deeper into the disk, changing the course of dust migration. Our proof-of-concept, two-dimensional, vertically-averaged simulations show that the combination of radiation pressure, shadowing, and gas drag can produce a net outward migration, or recession, of the dust component of the disk. The recession speed of the inner disk edge is on the order of $10^{-5}$ times Keplerian speed in our parameter space, which is faster than the background viscous flow, assuming a Shakura & Sunyaev viscosity alpha $\lesssim 10^{-3}$. This speed, if sustained over the lifetime of the disk, can result in a dust cavity as large as tens of au.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Dust gaps and rings appear ubiquitous in bright protoplanetary disks. Disk-planet interaction with dust-trapping at the edges of planet-induced gaps is one plausible explanation. However, the sharpness of some observed dust rings indicate that sub-mm-sized dust grains have settled to a thin layer in some systems. We test whether or not such dust around gas gaps opened by planets can remain settled by performing three-dimensional, dust-plus-gas simulations of protoplanetary disks with an embedded planet. We find planets massive enough to open gas gaps stir small, sub-mm-sized dust grains to high disk elevations at the gap edges, where the dust scale-height can reach ~70% of the gas scale-height. We attribute this dust 'puff-up' to the planet-induced meridional gas flows previously identified by Fung & Chiang and others. We thus emphasize the importance of explicit 3D simulations to obtain the vertical distribution of sub-mm-sized grains around gas gaps opened by massive planets. We caution that the gas-gap-opening planet interpretation of well-defined dust rings is only self-consistent with large grains exceeding mm in size.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： As one of the most commonly observed disk substructures, dust rings from high-resolution disk surveys appear to have different radial widths. Recent observations on PDS 70 and AB Aur reveal not only planets in the disk, but also the accompanying wide dust rings. We use three-dimensional dust-and-gas disk simulations to study whether gap-opening planets are responsible for the large ring width in disk observations. We find that gap-opening planets can widen rings of dust trapped at the pressure bump via planetary perturbations, even with the mid-plane dust-to-gas ratio approaching order unity and with the dust back-reaction accounted for. We show that the planet-related widening effect of dust rings can be quantified using diffusion-advection theory, and provide a generalized criterion for an equilibrated dust ring width in three-dimensional disk models. We also suggest that the ring width can be estimated using the gas turbulent viscosity $\alpha_{\rm turb}$, but with cautions about the Schmidt number greater than order unity.
点击量
待评议
点击量
下载量
评论
