TAP Colloquium - Zhi-Yun Li

Monday, Apr 22, 2013
4:00 pm
Location: Steward Observatory
Room: N210

Zhi-Yun Li
University of Virginia

Protostellar Disk Formation in Magnetized Clouds

The formation of stars and planets are connected through disks. Disk formation, once thought to be a trivial consequence of angular momentum conservation, is greatly complicated by the magnetic field that is observed to be present in the dense, star-forming cores of molecular clouds. Indeed, in the simplest case of perfect coupling between the magnetic field and bulk neutral core material (the ideal MHD limit), both analytic work and numerical simulations have shown that the formation of rotationally supported disks is suppressed by excessive magnetic braking in dense cores magnetized to the observed level. The disk suppression leads to the so-called ``magnetic braking catastrophe'' in star formation. I will discuss possible resolutions to this problem proposed to date, including non-ideal MHD effects, misalignment between the magnetic field and rotation axis, turbulence-enhanced magnetic reconnection, and outflow stripping of the slowly rotating protostellar envelope. The conclusion is that how protostellar disks form and grow remains an open question.

Tap Colloquia