Evolution and Dispersal of Protoplanetary Gas Disks

Grant #: NNX08AU37A
Senior Scientist: Uma Gorti

This study provides data for the modeling of the evolution of disks with a wide range of properties around stars of different masses, to study the lifetimes of disks and their capacity to form planets. This study uses our theoretical models of the density and thermal structure of gas in disks to compute mass loss rates due to photoevaporation, a disk destruction mechanism. We can thus estimate disk lifetimes. Our models predict gas line emission, and we compare model results with observational data to infer disk properties and to better determine stellar UV luminosities, a critical parameter in setting the photoevaporation rate from the inner, planet-forming regions of disks. The constraints set by this procedure help assess the lifetimes of disks with different initial conditions, and determine the likelihood of giant planet formation around stars. Disk properties are also expected to influence the formation of terrestrial planets in the habitable zone, and we study the effects of gas removal by photoevaporation on planet building processes. We thus determine the range of stellar and disk properties that are conducive to the formation of planetary systems, and therefore, to the origin of life.