INFRARED MAPPING OF M82 - A STARBURST IN AN EDGE-ON BARRED GALAXY

We present new 1-30-mu-m images of the starburst galaxy M82. The appearance of M82 at 2-mu-m indicates that a bar approximately 1 kpc long is located at its center. This bar may dramatically influence the gas dynamics and may have caused the formation of the central gas and dust toroid associated with the luminous episode of star formation. Our mid-IR maps define the structure of the toroid out to 30-mu-m and show that the extent of the emitting region is at least 1.3 kpc. The absorption optical depth determined from 1-2-mu-m colors corresponds to A(v) less-than-or-similar-to 8 and is distributed in a ridge spanning the starburst region and closely resembling the distribution of H I optical depth. Finally, we consider the contribution that very small grains may make to the 10-mu-m emission and conclude by comparison to Galactic H II regions that their mid-IR emission is significant.