TUNA Lunch Talk:

John Tobin

Department of Astronomy, University of Michigan

Morphological Complexity Protostellar Envelopes: Structure and Kinematics

September 28

12:10PM, Room 230, NRAO, Edgemont Road


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. To further characterize these systems, I have observed them in the dense gas tracers N2H+, N2D+, and ammonia which closely follow the extinction morphology. The magnitude of the velocity gradients on R ~ 10000 AU scales indicates that the velocity structure, which has historically interpreted as rotation, may really be large-scale infall. Furthermore, several systems show large velocity gradients and/or linewidths near the protostar, as expected for infall or increased rotational velocity in the inner envelope. Comparison with a 3D kinematic model shows that the position-velocity structure seen in many systems is better reproduced by filaments than sheets or spheres, further demonstrating that the structure of the envelope must be considered when interpreting the velocity field.