Detection of a Magnetized Disk around a Very Young Protostar
  We present subarcsecond resolution polarimetric observations of the 878 mum
thermal dust continuum emission obtained with the Submillimeter Array (SMA)
towards the IRAS 16293-2422 protostellar binary system. We report the detection
of linearly polarized dust emission arising from the circumstellar disk
associated with the IRAS 16293-2422 B protostar. The fractional polarization of
~1.4$% is only slightly lower than that expected from theoretical calculations
in such disks. The magnetic field structure on the plane of the sky derived
from the dust polarization suggests a complex magnetic field geometry in the
disk, possibly associated with a rotating disk that is wrapping the field lines
as expected from the simulations. The polarization around IRAS 16293-2422 A at
subarcsecond angular resolution is only marginally detected.
