Highly efficient star formation in NGC 5253 possibly from stream-fed accretion

TL;DR

This paper reports the detection of a dense, dusty gas cloud in NGC 5253 with an exceptionally high star formation efficiency exceeding 50%, likely driven by gas inflow from a streamer, illustrating highly efficient star formation in a dwarf galaxy.

Contribution

It provides the first detailed imaging of a dense gas cloud with extremely high star formation efficiency in NGC 5253, suggesting stream-fed accretion as a key mechanism.

Findings

Star formation efficiency exceeds 50%, much higher than in the Milky Way.

The gas cloud is hot, dense, dusty, and has a low gas-to-dust ratio.

Gas inflow from a streamer likely fuels the high-efficiency star formation.

Abstract

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.