The luminous starburst ring in NGC 7771: Sequential star formation?

Only two of the 20 highly luminous starburst galaxies analyzed by Smith et al. exhibit circumnuclear rings of star formation. These galaxies provide a link between similar to 10(11) L. luminosity class systems and classical, less-luminous ringed systems. In this paper, we report the discovery of a n ear-infrared counterpart to the 1.6 kpc diameter nuclear ring of radio emis sion in NGC 7771 (UGC 12815). The ring contains approximate to 10 radio-bri ght clumps and approximate to 10 near-infrared-bright clumps. A displacemen t between the peaks of the radio and the near-infrared emission indicates t he presence of multiple generations of star formation. The estimated therma l emission from each radio source is equivalent to that of similar to 35,00 0 O6 stars. Each near-infrared-bright knot contains similar to 5000 red sup ergiants, on average. In the case that the radio-bright knots are 4 Myr old and the near-infrared-bright knots are approximate to 10 Myr old, each kno t is characterized by a stellar mass of 10(7) M., and the implied time-aver aged star formation rate is similar to 40 M. yr(-1) Several similarities ar e found between the properties of this system and other ringed and nonringe d starbursts. Morphological differences between NGC 7771 and the starburst + Seyfert 1 galaxy NGC 7469 (UGC 12332) suggest that NGC 7771 may not be ol d enough to fuel an active galactic nucleus (AGN), or may not be capable of fueling an AGN. Alternatively, the differences may be unrelated to the pre sence or absence of an AGN and may simply reflect the possibility that star formation in rings is episodic.