ORCHESTRATION OF STARBIRTH ACTIVITY IN DISK GALAXIES: New Perspectives from Ultraviolet Imaging

Ultraviolet imaging of nearby disk galaxies reveals the star-forming activity in these systems with unprecedented clarity. UV images recently obtained with the Shuttle-borne Ultraviolet Imaging Telescope (UIT) reveal a remarkable variety of star-forming morphologies. The respective roles of tides, waves, and resonances in orchestrating the observed patterns of starbirth activity are discussed in terms of the extant UV data. WHY ULTRAVIOLET IMAGING? Despite the potential for obscuration by dust, a significant fraction of a disk galaxy’s UV emission manages to escape and thus be detected by instruments located beyond the Earth’s atmosphere. Even in disk galaxies of high inclination, UV imaging can reveal widespread emission (cf. Fanelli et al., Neff et al., & O’Connell, these Proceedings). Ultraviolet imaging of nearby disk galaxies reveals the star-forming activity with unprecedented clarity. Unlike imaging at Hα, UV imaging directly traces the full range of OBA stellar spectral types, thereby sampling the recent-epoch 1) UIT research is funded through the Spacelab Office at NASA Headquarters under Project number 440-51. c © 1995 American Institute of Physics 1