Massive star formation and dust in collisional ring galaxies: From GALEX to Spitzer

Abstract

We present some first results from a GALEX and Spitzer survey of a dozen collisional ring galaxies. The combination of UV and mid-IR imaging and spectroscopy will allow us to investigate the relationship between massive star formation sites, PAH molecular–band strengths, and dust heating in these mainly simultaneous starburst rings. A deep observation of the well-known Cartwheel ring galaxy has revealed a gigantic outer UV disk which extends to at least twice the radius of the outer blue star–forming ring. A lack of UV variability in the outer Cartwheel ring rules out an intermediate-mass black hole (IMBH) as the origin of the brightest of a dozen ULX source seen by Chandra in the ring.

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