Molecular Clouds Toward the Super Star Cluster NGC3603; Possible
  Evidence for a Cloud-Cloud Collision in Triggering the Cluster Formation
  We present new large field observations of molecular clouds with NANTEN2
toward the super star cluster NGC3603 in the transitions 12CO(J=2-1, J=1-0) and
13CO(J=2-1, J=1-0). We suggest that two molecular clouds at 13 km s-1 and 28 km
s-1 are associated with NGC3603 as evidenced by higher temperatures toward the
H II region as well as morphological correspondence. The mass of the clouds is
too small to gravitationally bind them, given their relative motion of ~20 km
s-1. We suggest that the two clouds collided with each other a Myr ago to
trigger the formation of the super star cluster. This scenario is able to
explain the origin of the highest mass stellar population in the cluster which
is as young as a Myr and is segregated within the central sub-pc of the
cluster. This is the second super star cluster along side Westerlund2 where
formation may have been triggered by a cloud-cloud collision.
