Observing the Earliest Phases of Protoplanetary Disk Formation

Friday, 14 February 2014
Water Tower (Hyatt Regency Chicago)
John Tobin Jr. , National Radio Astronomy Observatory, Charlottesville, VA
The formation of proto-planetary disks begins during the earliest phase
of the star formation process, while the nascent protostar is still
surrounded by a dense envelope of gas and dust. Using sub/millimeter
interferometry, we can probe through the dense envelope revealing the
the protostellar disk. However, the properties
of disks early in the protostellar phase are still quite uncertain as
there are currently only a few clear examples. Understanding the early
disks are important given that they set the initial conditions for
planet formation and may play a role in binary star formation through
fragmentation via gravitational instability. Moreover, the rotation
curve of these protostellar disks reveal the masses of the protostars,
an important parameter that has lacked observational constraint until
recently. Probing deeper, we also find binaries in a few protostellar
systems that with ~100 AU separations, a strong indication that the disks themselves are
fragmenting early-on. But statistics are not yet good enough to know how
binaries tend to form, whether through disk fragmentation or migration.
Our ability to detect disks and binaries early in the
protostellar phase has progressed to the point where a broad characterization is
needed, necessitating large surveys that we are beginning to conduct with the
VLA this fall toward all known protostars in the Perseus cloud.
Moreover, the sensitivity of ALMA promises to make observations of disk
kinematics routine toward protostars, enabling masses of a large number
of Class 0 protostars to be measured for the first time.