Photoevaporation
= Photoevaporation
{wiki}
Radiation heats gas sufficiently to drive an escaping thermal outflow. It can remove material from <protoplanetary disks>, planetary atmospheres and irradiated clouds. In a heated <Keplerian disk>, the <photoevaporative gravitational radius> compares the <sound speed> with the orbital speed. The mass-loss rate depends on the heating, density and wind geometry rather than radiation pressure alone.