The chaotic ISM of the post(?)-starburst galaxy NGC 1569

Abstract

We present the results and analysis of HST-wfpc2 imagery of the starburst galaxy NGC 1569 (d = 2.2 Mpc), which permit unprecedented resolution (~ 1pc) of the ionized gas and stellar population. The primary data in our analysis consists of images taken through narrow-band filters isolating Hβ, Hα, [O iii]λ5007, and [S ii]λλ6717+30, as part of go Program 8133. A variety of color-coded and grey-scaled maps of the morphology, ionization structure, and dust distribution are presented. Unsharp masks of the Hα images show a very chaotic structure for the ionized gas, with numerous filaments and arc-like bright rim features across the entire galaxy, but without significant large-scale ionization variations. Variations in the ionization and line-of-sight reddening occur on smaller scales (~ 10 – 50 pc), with numerous low-ionization semi-stellar knots seen throughout the main body of the galaxy, even within the ‘hole’ in the ionized gas distribution around the central super star clusters previously noted from H i maps. Several of these features have strong [S ii] emission indicative of being supernova remnants. We combine these data with archival wide-band HST-wfpc2 imagery to quantitatively evaluate the source(s) of the (largely photo-) ionized gas.