Ilaria PASCUCCI : Steward Observatory, University of Arizona

Gas in Disks around Sun-like Stars : Results from the FEPS Spitzer Legacy Program

The presence or absence of gas in circumstellar disks affects planet formation in fundamental ways. The initial gas mass determines the size and distribution of gas giant planets. Gas masses between 1 and 10 times the dust masses control the dust dynamics and shape the disk structure. Even during the assembly of terrestrial planets, earth masses of gas may be necessary to circularize the orbits of protoplanets.

In the context of the "Formation and Evolution of Planetary Systems" Spitzer legacy program we are carrying out a comprehensive survey of gas in post-accretion and debris disks. I will present our infrared and millimeter spectra and show that we can set tight constraints on the amount of gas in the planet forming region 1-30 AU of the targeted disks. These values combined with the estimated ages of our systems (between 5 and 100 Myr) provide important insight into the formation of giant and terrestrial planets.