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S.C. Beck (Tel Aviv University), J.L. Turner (U.C.L.A.), V. Gorjian (JPL)
We present subarcsecond resolution infrared continuum images of the compact radio continuum sources in the dwarf starburst galaxies NGC 4214, II Zw 40 and He 2-10. The ratio of mid-infrared to radio flux observed is typical of HII regions, arguing that these small and optically thick radio sources are in fact nebulae excited by young stars rather than non-thermal objects. Each source requires the ionization of hundreds to thousands of O stars to maintain it. These nebulae have very high gas densities and are heavily obscured, indications that they are very young. We believe these are recently formed Super Star Clusters, still embedded in their natal clouds. In II Zw 40 and He 2-10 we find that these sources, a few parsecs or at most tens of parsecs across, are producing all the infrared flux seen by IRAS beams that include the entire galaxy. These are extreme examples of how concentrated star formation in starburst galaxies can be.
This work was supported in part by the National Science Foundation and the Sackler Institute of Astronomy.
The author(s) of this abstract have provided an email address for comments about the abstract: sbeck@cfa.harvard.edu