We present observations of CO ( 3–2 ) and ^ { 13 } CO ( 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 \farcs 3 resolution images reveal an unusual molecular cloud , “ Cloud D1 ” , coincident with the radio-infrared supernebula .
The \sim 6 -pc diameter cloud has a linewidth , \Delta v = 21.7 km s ^ { -1 } , that reflects only the gravitational potential of the star cluster residing within it .
The corresponding virial mass is 2.5 \times 10 ^ { 5 } M _ { \odot } .
The cluster appears to have a top-heavy initial mass function , with M _ { * } \ga 1 -2 M _ { \odot } .
Cloud D1 is optically thin in CO ( 3–2 ) probably because the gas is hot .
Molecular gas mass is very uncertain but constitutes < 35 % of the dynamical mass within the cloud boundaries .
In spite of the presence of an estimated \sim 1500 - 2000 O stars within the small cloud , the CO appears relatively undisturbed .
We propose that Cloud D1 consists of molecular clumps or cores , possibly star-forming , orbiting with more evolved stars in the core of the giant cluster .