A NUCLEAR STARBURST RING IN THE SPIRAL GALAXY NGC-7552

We present radio maps of NGC 7552 that reveal a 1 kpc starburst ring not visible in single color optical images, largely because of dust. The radio emission from the ring is dominated by supernova remnants. There is little or no radio emission from the nucleus itself. Combined with broadband optical, near-infrared and narrow band Halpha images, we discuss the star formation activity in the circumnuclear region. In particular, we suggest that a burst of star formation occurred in the ring about 5 X 10(7) yr ago. The current SN rate is about one every 2-3 years. As well as the nuclear starburst ring, we identify two larger scale rings which are also associated with continuing star formation. These rings have similar dimensions to the outer, inner, and nuclear ring classification of Buta, and we interpret them in terms of orbital resonances due to a large scale bar. NGC 7552 may also possess a nuclear bar and an outflowing superwind, but further observations are required for confirmation. We speculate that nuclear rings may act as a depository for inflowing material and play a role in funneling an outflowing superwind.