ALMA Detects CO(3-2) within a Super Star Cluster in NGC 5253

We present observations of CO(3-2) and 13CO(3-2) emission near the supernebula in the dwarf galaxy NGC 5253, which contains one of the best examples of a potential globular cluster in formation. The 0 3 resolution images reveal an unusual molecular cloud, "Cloud D1," that is coincident with the radio-infrared supernebula. The ∼6 pc diameter cloud has a linewidth, Δ v = 21.7 , that reflects only the gravitational potential of the star cluster residing within it. The corresponding virial mass is 2.5 × 105 . The cluster appears to have a top-heavy initial mass function, with M* 1-2 . Cloud D1 is optically thin in CO(3-2), probably because the gas is hot. Molecular gas mass is very uncertain but constitutes