HII Regions and Extinction in the Spiral Galaxy M83
Abstract
We have obtained narrow-band Hα imaging and radio continuum synthesis maps for the nearby southern spiral galaxy M83 (NGC 5236) in order to study the variation of the extinction due to dust across the disk of the galaxy. The Australia Telescope Compact Array has been used in 3 of its highest resolution configurations to map M83 in both the 6 cm and the 13 cm continuum, so that non-thermal sources can be distinguished from Hii regions. By comparing the optical Hα and thermal radio continuum flux ratios of individual Hii regions with those expected from theory, we wish to test whether or not M83 possesses a well-defined radial extinction gradient. Previous searches for such a gradient in M81 (Kaufman et al. 1987, ApJ, 319, 61) and M51 (van der Hulst et al. 1988, A&A, 195, 38) have been inconclusive, but the high Hii region luminosities and significant dust content of M83 make it one of the best candidates for such a study. We present here the preliminary results of an analysis of this data, and outline some implications for the topical issue of opacity in spiral disks.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1994
- Bibcode:
- 1994AAS...185.7601H