A GBT Argus Survey

Despite its undisputed importance to understanding disk formation and stellar multiplicity, the kinematics of star-forming cores at scales of 0.01 − 0.05 pc (2,000 – 10,000 AU) have not been well characterized because of a lack of the required sensitivity and high spatial and spectral resolution until now. Building on a successful pilot study, this large program capitalizes on the unique capabilities of GBT-Argus to survey the kinematics of all starless and Class 0 protostellar cores in Perseus down to ~0.01 pc scales with <0.05 km/s velocity resolution using the widely-used dense gas tracer N2H+.

Herschel column density map of the actively star-forming Perseus molecular cloud over-plotted with the 108 protostellar (stars) and starless (circles) targets proposed in this large program.

Stars form through gravitational collapse of dense cores within the molecular clouds, where multi-scale supersonic turbulent flows compress low density material to initiate creation of overdense regions. There have been several observational projects aimed at resolving the velocity structure at larger (clouds) and smaller (protostellar disks) scales, but the kinematics within dense cores, which contains the information of material destined to become incorporated with disks and subsequently accreted onto the star or form planets, remains less well-investigated, because this scale (0.01-0.05 pc, or ~ 7-35” in nearby clouds with distance d ~ 300 pc) is generally beyond the resolution of single-dish telescopes for low-J molecular transitions that trace these cold dense gas, while most interferometers cannot cover such a large spatial area with the necessary velocity resolution within a reasonable amount of time.

GBT-Argus is ideal to map such cores with its unique combination of the enhanced sensitivity and mapping speed of the recently-commissioned Argus focal plane array with the 0.005 km/s channel width and 9” angular resolution of the GBT at ∼ 90 GHz. This large program will conduct a high-spectral resolution (<0.05 km/s), high sensitivity N2H+ J=1-0 line (93.17 GHz) mapping survey to systematically characterize the internal velocity structures of 108 young cores in Perseus molecular cloud which span a range of star forming environments.

The DiSCo survey will address a key open question in star formation: the origin and distribution of angular momenta of star-forming cores. Our broad statistical approach is essential to understanding the range of intrinsic behavior, the statistically most common behaviors, and how those behaviors correlate with stellar outcome and environment. By characterizing the detailed kinematics of more than 100 cores, this GBT Large Program will address the angular momentum question with a statistically broad sample and provide many opportunities for ancillary science by the star formation community worldwide.