\title{HII Structures in the Middle Disk of M31}

\author{W. Ashman, J. S. Gallagher, E. Wilcots} 
\affil{University of Wisconsin---Madison}
We present a deep, narrow-band H$\alpha +$ [N II] image that
shows a variety of emission line objects in the middle disk
of M31 along the minor axis.  The observations were obtained
with the WIYN 3.5-m telescope under excellent conditions with
0.7 arcsec FWHM images.  These data include the large
HII regions 405 and 406, catalogued by Baade \& Arp
(1964, ApJ, 139, 1027) in the main star-forming
ring of M31, as well as smaller HII regions in the inner
disk. In addition several faint, large ionized
shells and numerous unresolved sources are present. We analyze the
symmetries of larger ionized structures as a means to search
for the effects of an anisotropic pressure component that
could be produced by an organized, large-scale magnetic
field. The taxonomy of ionized structures in this part of M31 also
is briefly summarized.
Date: Fri, 5 Apr 96 18:32:53 EST

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