is a typical and probably the most well-known
starburst galaxy and has been extensively studied in nearly all wavelength
ranges. Although M 82 is classified as a dwarf irregular galaxy, it is very
similar to many of the starburst galaxies discussed here, in particular
NGC 1808.
High-resolution observations by Kronberg, Bierman & Schwab (1985) show that
the continuum emission is concentrated into a large number of compact sources,
identified as very young supernova remnants. A cylindrical outflow of dense
molecular clouds and ionized gas has been observed, ejected from the disk into
the halo at several hundred kms-1 (Nakai et al. 1987; Bland & Tully
1988). HI absorption lines shifting over the continuum source(s)
clearly indicate a fast-rotating nuclear ring (Weliachew, Fomalont & Greisen
1984; Yun 1992). Telesco et al. (1991) report the detection of a bar 1
kpc long; the nuclear ring (radius
300 pc) lies roughly between the
ILR(s) which are found at 40 and 600 pc.