Gas flows around 2 young stellar clusters in NGC2264

Abstract

Observations of the dust and gas toward two young stellar clusters, IRS1 and IRS2, in the NGC2264 star forming region are presented. Continuum emission is used to locate the dusty envelopes around the clusters and individual protostars within and line emission from the J=3-2 transitions of HCO+ and H13CO+ is used to diagnose the gas flows around them. The molecular abundance, velocity centroid and dispersion are approximately constant across the IRS1 clump. With these constraints, the self-absorbed HCO+ lines are modeled as a large scale collapse, with speed v_in=0.3 km/s and mass infall rate dM/dt=4e-4 Msun/yr, falling onto an expanding central core. The signature of large scale collapse, with a similar speed and mass infall rate, is also found toward IRS2 but again appears disrupted at small scales. Individual protostars are resolved in this cluster and their size and velocity dispersion show that the stellar system is currently bound and no older than 0.5 Myr, but is destined to become unbound and disperse as the surrounding cloud material is lost.