Filamentary Flows in the Serpens South Protocluster Helen Kirk Harvard Smithsonian Center for Astrophysics, Cambridge, USA
Most stars appear to form within clustered environments, and yet clustered star formation is still poorly understood relative to stars forming in isolation. At the earliest stages, one important puzzle is how sufficient mass accumulates in the cluster centre. Several models and simulations suggest that accretion flows along associated filaments are key, but this is ill-constrained, observationally. Serpens South, a recently discovered cluster forming deeply embedded in a prominent dense filament, is an ideal region to test the filamentary accretion flow scenario. A wealth of data has already been collected on this region since its discovery in 2008 including a catalog of the YSO population, suggesting the cluster is the youngest known, polarization measurements suggesting a strong magnetic field, and an outflow catalog. We present an analysis of Mopra observations of Serpens South in several molecular lines including N2H+, HCO+, and H13CO+. These observations are consistent with a flow gradient of ~1km/s/pc along the filament axis. Furthermore, the entire region appears to be undergoing global infall, showing strongly blue-asymetric emission in optically thick lines with typical delV values of order -1. The inferred radial column density profile of the filament is much shallower than the isothermal cylinder model, similar to recent Herschel results in IC 5146. We discuss the implications of our observations with respect to the filamentary accretion flow scenario.
Collaborators: P. Myers, CfA, USA T. Bourke, CfA, USA