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Event Detail Information

Event Detail Information

Astrophysics Colloquium - John Tobin, NRAO, Charlottesville, VA: "Protostellar Envelope Structure and a Forming Protostellar Disk"

Speaker John Tobin
Date May 1, 2012
Time 4:00 pm  
Location 134 Astronomy
Sponsor Astronomy Department
Contact Charles Gammie
Event type Colloquia
Views 7773
The morphology and kinematics of infalling envelopes around protostars determine the structure of the forming protostellar disk and reflect back on the initial properties of their parent dark clouds. 8 micron shadow images from Spitzer show that the dense envelopes around Class 0 protostars are generally morphologically complex, often filamentary, and frequently non-axisymmetric. The observed envelope structure indicates a likely origin in turbulent cloud structure rather than a quasi-static formation and increase the likelihood of fragmentation during collapse, forming close binaries. The magnitude of the velocity gradients measured using N2H+/ammonia data indicates that the velocity structure, which has historically interpreted as rotation, may have significant contributions from large-scale infall. Moreover, the position-velocity structure of the line emission is more consistent with an infalling filament rather than a sphere. Inside these complex envelopes, there is a proto-planetary disk forming, even during the earliest phase of the star formation process. Millimeter interferometer observations from CARMA and the SMA are able to resolve the structure of an edge-on forming proto-planetary disk around the Class 0 protostar L1527 in Taurus. The disk is found to have most properties comparable to more evolved disks, but extremely flared. These results indicate that disks may grow rapidly during the early stages of protostellar evolution and already have similar characteristics to their more evolved counterparts.