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Session 89 - Star-forming Galaxies.
Oral session, Friday, January 09
International Ballroom East,

[89.06] Ultraviolet Imaging of Starburst Rings in Disk Galaxies at Low and High Redshift

W. H. Waller (NASA/GSFC/LASP, Hughes STX, and Tufts U.), M. N. Fanelli (NASA/GSFC/LASP and Hughes STX), T. P. Stecher, UIT Science Team (NASA/GSFC/LASP)

Imaging in the restframe ultraviolet has proven to be an effective and vital means of tracing starbirth activity in galaxies out to high redshifts. Using images from the Ultraviolet Imaging Telescope (UIT), Hubble Space Telescope (HST), and complementary optical telescopes, we have investigated the starburst activity and associated dynamics in nearby ringed disk galaxies. Concentrating on the Sab-type starburst-ring galaxy M94 (NGC 4736), we find that most of the star formation is being orchestrated via a nuclear mini-bar/inner-ring/oval-disk/outer-ring dynamic. The inner starburst ring and bi-symmetric knots at intermediate radius, in particular, argue for bar-mediated resonances as the primary drivers of evolution in M94 at the present epoch. Similar ring-bar dynamics may prevail in the centers of the ``core-halo'' galaxies that have been marginally resolved at high redshift. The gravitationally lensed ``Pretzel Galaxy'' (0024+1654) at a redshift of \sim2 provides an important precedent in this regard, wherein reconstructions of the galaxy's emitting structure clearly show an annular morphology in the restframe UV. \vskip 24pt

\centerline Reference \vskip 12pt

\hang Waller, W. H. et al. 1997, in The Ultraviolet Universe at Low and High Redshift: Probing the Progress of Galaxy Evolution, eds. W. H. Waller, M. N. Fanelli, J. E. Hollis, amp; A. C. Danks (New York: AIP Press), p. 39

Program listing for Friday