FUV-Driven Photoevaporation of protoplanetary Disks

年轻恒星周围环绕着气态圆盘，这很可能是行星的诞生地。关键问题之一是：在行星形成过程中，圆盘中还能有多长时间有足够的尘埃和/或气体可供使用，以及这些物质的大部分将在哪里？观测估计得出的盘片寿命为几百万年。这比经典的粘性吸积盘模型可以解释的要短得多，所以很明显，一定存在一些主动破坏盘的过程。无论这个过程是什么，它很可能也会严重影响物质在盘中的分布，这是行星形成的一个关键问题，在观测上是不受限制的。在这个方案中，我们打算研究原行星盘光蒸发的过程，作为盘的破坏机制。目前，由EUV光子(13.6-100 eV)和来自主星的X射线提供动力的光蒸发已经相当清楚，但由来自主星的FUV光子(6-13.6 eV)提供动力的蒸发只被非常微不足道地理解，因为它要复杂得多。然而，初步的工作表明，紫外光驱动的光蒸发可能是主要的机制。这项提议的目标是通过开发这一过程的自洽数值模型来理解由紫外光驱动的光蒸发，以及它如何影响这些行星系统摇篮中的物质分布。

Young stars are surrounded by gaseous disks which are the likely birthplaces of planets. One of the key questions is: How long will there be enough dust and/or gas in the disk available for the planet formation process, and where will most of this matter be? Observational estimates yield disk life times of a few million years. This is much shorter than classical viscous accretion disk models can explain, so clearly some process must exist that actively destroys the disk. Whatever this process is, it will likely severely affect the distribution of matter in the disk as well, a critical issue for planet formation that is observationally ill constrained. In this proposal we intend to study the process of photoevaporation of protoplanetary disks by their own host star as the disk destruction mechanism. Photoevaporation powered by EUV photons (13.6 - 100 eV) and X-rays from the host star is reasonably well understood nowadays, but evaporation powered by FUV photons (6 - 13.6 eV) from the host star is only very marginally understood because it is much more complex. Yet, preliminary work indicates that FUV-driven photoevaporation might be the dominant mechanism. The goal of this proposal is to understand FUV-driven photoevaporation by developing self-consistent numerical models of this process, and how it affects the matter distribution in these cradles of planetary systems.