Circumnuclear star formation in the early-type resonance ring barred spiral galaxy NGC 1326

We present multiband WFPC2 images of the nuclear ring of NGC 1326, an early -type southern barred spiral in the nearby Fornax galaxy cluster. The ring is a typical example of a 1 kpc-sized star-forming ring located in the regi on of the inner Lindblad resonances with the weak primary bar. The images r eveal nearly 1000 point sources in and around the ring. Those sources brigh ter than M-v = -9 are probably massive young clusters, while the fainter so urces may include a mix of extremely luminous stars and fainter clusters. F rom an analysis of reddening-free parameters and two-color plots, we find e vidence for a spread in ages of ring clusters, from less than 5 Myr to at l east 200 Myr. The older clusters still lie within the nuclear ring, with no evidence of migration of the ring being found over this time period. The l uminosity function reveals no clusters having an (uncorrected) absolute mag nitude M-v brighter than -11, and even after correction for extinction the most luminous cluster identified has only M-v(0) = -12.6. The ring seems to lack the "super-star clusters" (SSCs) seen in starburst systems and in oth er nuclear rings, and the analysis suggests that SSCs are not a universal p roperty of these rings. Complex dust structure is found inside the ring, so uth of the nucleus, and extinction is especially severe on the west side of the ring. An H alpha image reveals hundreds of H II regions and emission c omplexes in the nuclear ring, but there is little correlation between these H II regions and the observed continuum sources, most likely owing to redd ening and age differences in the ring.