Highly efficient star formation in NGC 5253 possibly from stream-fed
  accretion
  A local dwarf galaxy, NGC 5253, has a young super star cluster that may
provide an example of highly efficient star formation. Here we report the
detection and imaging, with the Submillimeter Array, of the J= 3-2 rotational
transition of CO at the location of the massive cluster associated with the
supernebula. The gas cloud is hot, dense, quiescent, and extremely dusty. Its
gas-to-dust ratio is lower than the Galactic value, which we attribute to dust
enrichment by Wolf-Rayet stars within the embedded star cluster. Its star
formation efficiency exceeds 50%, ten times higher than clouds in the Milky
Way: this cloud is a factory of stars and soot. We suggest that high efficiency
results from the force-feeding of star formation by a streamer of gas falling
into the galaxy.
