Collaborative Research: The Evolution of Winds in Dust Disks Around Stars

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Planets formed from material in disks of gas and dust that once surrounded the stars they orbit. The way that these disks form and how material is spread throughout the disks affect both how quickly material is added to the stars themselves and what types of planets can form in the disks. Disk winds play a major role in the way this material is dispersed. In this study, the investigators build on their earlier work where they observed the disk winds in 33 disks. They observed two parts to the winds: a wind driven by magnetic/electric interactions and a wind driven by temperature differences. With this grant the investigators will extend their study to include a large number of much older disks with the goals of measuring how much the magnetic/electric process drives with wind and how much the thermal heating drives the wind. This project serves the national interest as it expands our understanding of the science behind the formation of planetary systems around other stars. A graduate student, a postdoc, and at least three undergraduate students will participate in this study. The investigators will also participate in a K-12 teacher workshop at The University of Arizona, reaching Hispanic and Native American communities. A two-week long astronomy class will be taught to high school girls from around the world in the annual Smith Summer Science and Engineering Program. The analysis of optical [OI] emission lines for the 33 disks in Taurus reveals two low-velocity kinematic components, one of which (broad component) likely traces a magnetohydrodynamic (MHD)-driven wind while the other (narrow component) might be associated with a thermally-driven wind. The investigators will establish empirically how disk winds evolve by measuring the relative proportion of MHD-driven and thermally-driven winds. They will also measure wind mass loss rates through the main stages of disk evolution and dispersal. They will extend their analysis of the [OI] lines to a sample of more evolved disks, including more disks with dust cavities, and analyze one of the blue [SII] transitions to clarify the thermal contribution to the [OI] emission.