The Initial Phases of Solar System and Binary Star Formation
John Tobin



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 a large survey that we are beginning to conduct with the VLA this fall toward all known protostars in the Perseus cloud. Moreover, the sensitivity of ALMA will 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.