Lincoln Greenhill: Moving Images of Accretion and Outflow in High-Mass Star Formation

Colloquium | November 5 | 4:10-5 p.m. | 2 LeConte Hall

Speaker/Performer: Lincoln Greenhill, CfA

Sponsor: Astronomy, Department of

The details of how massive stars form are poorly understood. Testing
the viability of disk-mediated accretion, and identifying the processes
that extract angular momentum benefit from direct measurement
of the dynamics of gas at small radii, where outflows are launched and
collimated. Using the VLBA and VLA, and for the first time, we have
traced gas structures and tracked 3-D motions within them, 10-1000 AU
from a high-mass YSO. We resolve an edge-on disk about 50 AU across and
measure its rotation. We also resolve a wide-angle outflow that
collimates at radii beyond 100 AU. The implied dynamical mass is about 8
Msun. Close to the disk, curved streamlines suggest that magnetic fields
may play a role in launching the outflow. The YSO is quite highly
embedded, without known emission up to 20 um. This is consistent with
the inferred edge-on disk orientation and high column density. I will
discuss possible origins for this disk.

Event Contact: steph@astro.berkeley.edu, 510-642-5275