Thermochemical Structure and Photoevaporation of X-ray Irradiated Protoplanetary Disk Atmospheres
First Author:
Barbara Ercolano
Email: be AT ast.cam.ac.uk
University of Cambridge, IoA
Madingley Road
Cambridge, CB3 0HA, UK
Coauthors:
Drake, Jeremy, SAO, Cambridge, MA
Clarke, Cathie, IoA, Cambridge, UK
Raymond, John, SAO, Cambridge, MA
Abstract
The evolution of protoplanetary discs and of their planetary progeny is controlled by heating and irradiation from the central star - from IR to X-rays - but in the vicinity of OB stars can also be significantly affected by the external radiation environment. Observations of protoplanetary discs have already begun to represent an important aspect of Spitzer's legacy, these and other observations are providing insight into problems such as the timescales for grain growth and gas dissipation, angular momentum transport - issues central to understanding the likelihood of forming planetary systems like our own. While the observational database continues to grow, and several studies have focused on the properties of the dust component of the disc atmospheres, studies of the gaseous component of the inner discs have only recently been attempted. So far only a rough picture of the thermochemical structure of this crucial component has been provided. I will present results from our 2D photoionisation and dust radiative transfer modeling of realistic, irradiated T-Tauri disks, highlighting their decoupled dust and gas temperature structure and ionisation structure, and discussing the contribution of X-ray photoevaporation to disk dissipation. Gas-phase diagnostics (e.g. [NeII] 12.8 um) will be mapped across the disk surface, and predictions will be made for useful gas-phase diagnostics that are detectable with current instrumentation or will become so in the near future.
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