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 H ^ { 13 } CO ^ { + } 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 ^ { -1 } } and mass infall rate \dot { M } = 4 \times 10 ^ { -4 } ~ { } M _ { \odot } yr ^ { -1 } , 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 5 \times 10 ^ { 5 } yr , but is destined to become unbound and disperse as the surrounding cloud material is lost .