Hubble Space Telescope Images of Nuclear Rings in NGC 6951 and NGC 1097

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Session 105 -- Barred Spirals
Display presentation, Thursday, 12, 1995, 9:20am - 6:30pm

[105.08] Hubble Space Telescope Images of Nuclear Rings in NGC 6951 and NGC 1097

A. J. Barth, L. C. Ho, A. V. Filippenko (UC Berkeley), W. L. W. Sargent (Caltech)

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.

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