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J.M. Cannon (Univ. of Minnesota), N.M. McClure-Griffiths (ATNF), E.D. Skillman (Univ. of Minnesota)
We present new multi-configuration HI aperture synthesis imaging of the nearby (D = 3.9 +/- 0.2 Mpc) dwarf starburst galaxy NGC 625 obtained with the Australia Telescope Compact Array. Analysis confirms the main results of lower-resolution VLA imaging by Cote, Carignan, and Freeman (2000). The HI velocity field is highly disturbed, with a component of large-scale rotation about the galaxy's major axis, suggestive of a recent tidal encounter as a potential trigger of the current starburst. The HI column density distribution, on the other hand, is comparatively smooth on large scales, although the inner regions do show multiple emission peaks spread throughout the disk of the galaxy. Comparing to our previous HST/WFPC2 imaging (Cannon et al. 2003), we find that the location of the major starburst is not coincident with the HI column density maximum, but is offset to the east by roughly 300 pc. Furthermore, the recent star formation is widespread throughout the HI disk, suggestive of sustained star formation and consistent with our HST star formation history analysis, where an elevated star formation rate has been present during the last 100 Myr. We also detect strong radio continuum emission from the largest HII region; comparing to our HST and ground-based H Alpha fluxes suggests either appreciable amounts of extinction toward the starburst region or the contribution of non-thermal sources to the radio continuum luminosity.
This work has been supported by NASA GSRP Fellowship NGT 5-50346, the National Radio Astronomy Observatory, and the University of Minnesota.
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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.