Institute of Astronomy

Protoplanetary disk demographics

SpeakerTalk DateTalk Series
Jonathan Williams31 July 2014Across HR 2014 Talks


The remarkable abundance of exoplanets tells us that the natural end state of a circumstellar disk is a planetary system. Moreover, disk evolution is known to be varied and stellar mass dependent and this is likely a key factor in the great diversity of exoplanet properties. Millimeter wavelength observations provide the best means for measuring disk masses, both of the dust and gas, and for following the growth of dust grains. I will discuss the results from SMA, IRAM and JCMT millimeter surveys of disks over a range of ages and infrared evolutionary states that provide important demographic information for comparing to exoplanet statistics. Disk dust masses decrease within time such that most of the solid mass resides in millimeter and larger sized particles within about 3 Myr. Isotopologue CO line fluxes are lower than expected for an ISM gas-to-dust ratio of 100. Either gas masses are very low (Jupiter masses or less) in Class II disks or there are new chemical pathways not seen in clouds or cores that lock carbon up in the solid component. Although disk luminosities rapidly decrease with time, the future is bright with ALMA. I will end by presenting new ALMA results on photo evaporating disks in Orion which demonstrate the promise of this facility for strengthening the connection between protoplanetary disk evolution and exoplanet diversity.