The Ultraviolet and Infrared Star Formation Rates of Compact Group
  Galaxies: An Expanded Sample
  Compact groups of galaxies provide insight into the role of low-mass, dense
environments in galaxy evolution because the low velocity dispersions and close
proximity of galaxy members result in frequent interactions that take place
over extended timescales. We expand the census of star formation in compact
group galaxies by \citet{tzanavaris10} and collaborators with Swift UVOT,
Spitzer IRAC and MIPS 24 \micron\ photometry of a sample of 183 galaxies in 46
compact groups. After correcting luminosities for the contribution from old
stellar populations, we estimate the dust-unobscured star formation rate
(SFR$_{\mathrm{UV}}$) using the UVOT uvw2photometry. Similarly, we use the MIPS
24 \micron\ photometry to estimate the component of the SFR that is obscured by
dust (SFR$_{\mathrm{IR}}$). We find that galaxies which are MIR-active
(MIR-"red"), also have bluer UV colours, higher specific star formation rates,
and tend to lie in H~{\sc i}-rich groups, while galaxies that are MIR-inactive
(MIR-"blue") have redder UV colours, lower specific star formation rates, and
tend to lie in H~{\sc i}-poor groups. We find the SFRs to be continuously
distributed with a peak at about 1 M$_{\odot}$ yr$^{-1}$, indicating this might
be the most common value in compact groups. In contrast, the specific star
formation rate distribution is bimodal, and there is a clear distinction
between star-forming and quiescent galaxies. Overall, our results suggest that
the specific star formation rate is the best tracer of gas depletion and galaxy
evolution in compact groups.
