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We present new and archival Hubble Space Telescope images of the well-known circumnuclear rings in the barred galaxies NGC 6951 and NGC 1097. The images resolve the rings into two-armed spirals of H II regions and clumps of bright stars that appear on the leading edges of strong dust lanes. There is no apparent star-forming activity interior to the rings, but intricate patterns of narrow dust lanes wind between the rings and the nuclei of the galaxies. The ring in NGC 6951 has a major axis diameter of 9\arcsec, corresponding to a linear size of approximately 900 pc, while the NGC 1097 ring is 18\arcsec\/ or 2 kpc in diameter (corrected for inclination, and assuming $H_0 = 75$ km s$^{-1}$ Mpc$^{-1}$). The morphology of these rings is similar to other well studied examples (such as in NGC 4314 and NGC 7552), suggesting that the two-armed structure seen here is generic to nuclear rings in barred galaxies. This morphology is in accord with the results of recent simulations which have shown that in a barred potential, gas flows inward in dust lanes that extend along the bar and curve around the nucleus, feeding a high star formation rate in a circumnuclear ring.
The image of NGC 1097, taken on 30 September 1992, also contains the Type II supernova 1992bd 12 days prior to its discovery in ground-based optical images.
