  Photoevaporation may provide an explanation for the short lifetimes of disks
around young stars. With the exception of neutral oxygen lines, the observed
low-velocity forbidden line emission from T Tauri stars can be reproduced by
photoevaporating models. The natural formation of a gap in the disk at several
AU due to photoevaporation and viscous spreading provides a possible halting
mechanism for migrating planets and an explanation for the abundance of
observed planets at these radii.
