Hα, SCUBA and MERLIN imaging of NGC 4490

Abstract

We describe Ha, SCUBA and MERLIN imaging of the interacting galaxy pair NGC 4490 and 4485. We detect an Ha filament emerging from the disc of NGC 4490 to a projected distance of 3 kpc which has counterparts in both the radio continuum and Hi. The HI counterpart extends to a projected distance of ∼ 30 kpc from NGC 4490 and we argue that this is evidence that the giant HI envelope in this system has its origins in star formation. We use SCUBA and radio continuum data to attempt to place constraints on the distribution of dust with respect to the star forming regions. This analysis is limited by the lack of an independent estimate of the dust temperature, something that both 'SIRTF' and 'SOFIA' will be able to provide, however we find some evidence that most obscuring dust is not located within HII regions themselves.