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Highly efficient star formation in NGC 5253 possibly from stream-fed accretion.
J L Turner1, S C Beck2, D J Benford3
1Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095-1547, USA.
Nature
|March 20, 2015
Summary
Star formation in galaxies is inefficient, but a dense, dusty gas cloud in NGC 5253 shows over 50% efficiency. This high rate may be fueled by infalling gas, explaining ancient massive star cluster formation.
Area of Science:
- Astronomy
- Astrophysics
- Galaxy Evolution
Background:
- Star formation efficiency in galaxies is generally low, impacting galaxy evolution and the survival of star clusters.
- The existence of ancient globular clusters suggests higher star formation efficiencies in the early universe.
- The dwarf galaxy NGC 5253 hosts a young, massive star cluster providing a potential case study for efficient star formation.
Purpose of the Study:
- To investigate the properties of a gas cloud associated with a massive young star cluster in the dwarf galaxy NGC 5253.
- To determine the star formation efficiency within this specific gas cloud.
- To understand the conditions that may lead to highly efficient star formation.
Main Methods:
- Detection of the J = 3→2 rotational transition of carbon monoxide (CO) using radio astronomy.
- Analysis of the gas cloud's physical properties: temperature, density, and dust content.
- Comparison of the gas-to-dust ratio with that of the Milky Way.
Main Results:
- The gas cloud is characterized by high temperature, density, and extreme dust content.
- The gas-to-dust ratio is significantly lower than the Galactic average, likely due to dust enrichment from the embedded star cluster.
- The star formation efficiency within this cloud exceeds 50%, which is approximately tenfold higher than typical galactic values.
Conclusions:
- The observed high star formation efficiency in NGC 5253's gas cloud is attributed to its unique physical conditions, including high density and dust content.
- The low gas-to-dust ratio suggests enrichment by the young, massive star cluster.
- Infalling gas streams ('force-feeding') are proposed as a mechanism driving this enhanced star formation, potentially mirroring conditions in the early universe.
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