FUV-Driven Photoevaporation of protoplanetary Disks

年轻的恒星被气体盘包围，这些气体盘很可能是行星的诞生地。其中一个关键问题是：在行星形成过程中，圆盘中有足够的尘埃和/或气体可以存在多久？这些物质大部分在哪里？观测估计得出的磁盘寿命为几百万年。这比经典粘性吸积盘模型所能解释的要短得多，所以很明显，一定存在某种主动破坏吸积盘的过程。无论这个过程是什么，它很可能也会严重影响圆盘中物质的分布，这是行星形成的一个关键问题，但在观测上却受到了限制。本论文拟研究原行星盘被其宿主恒星光蒸发的过程，作为原行星盘的破坏机制。由EUV光子（13.6 - 100 eV）和来自宿主恒星的x射线驱动的光蒸发现在已经相当好地理解了，但是由来自宿主恒星的FUV光子（6 - 13.6 eV）驱动的蒸发只是非常有限的理解，因为它要复杂得多。然而，初步的工作表明，fuv驱动的光蒸发可能是主要的机制。本提案的目标是通过开发该过程的自一致数值模型来理解fuv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.