ASTRO-1 ULTRAVIOLET IMAGING OF THE 30 DORADUS AND SN-1987A FIELDS WITH THE ULTRAVIOLET IMAGING TELESCOPE

During the Astro-1 mission, near- and far-UV images of selected fields in the Magellanic Clouds were obtained using the Ultraviolet Imaging Telescope (UIT). These ultraviolet images, centered on SN 1987A, 30 Doradus, supernova remnants N49A+B, and SMC-A, provide the first wide-field (40' in diameter), high spatial resolution (2"-3") UV images of these regions. The 30 Doradus data reveal a rich field of luminous. UV-bright stars, clusters, and associations: within the 3' diameter central cluster, there are 181 stars brighter than m2558 = 16.5, and 197 stars brighter than M1615 = 16.4. We have derived UV fluxes from the 30 Doradus central cluster and from its UV-bright core, R136. A region within 5" of R136 produces approximately 14% of the far-UV flux (lambda = 1892 angstrom) and approximately 16% of the near-UV flux (lambda = 2558 angstrom) emitted from the 3' diameter central cluster. The derived UV luminosity of R136 at 1892 angstrom is only 7.8 times that of the nearby O6-O7 Iaf star, R139, and the m1892 - m(v) colors of R136 are similar to other O or Wolf-Rayet stars in the same region. The UIT data, combined with published observations at longer wavelengths, indicate that there is no observational evidence for a supermassive star in R136. In the UIT images, we also detect an extensive dust feature, which extends throughout the 30 Doradus and SN 1987A fields. Diffuse UV emission at low flux levels runs from northeast to southwest at the northern boundary of N157A, N157B, and N157C, corresponding closely to the extended infrared emission seen in the IRAS 60-mu-m high-resolution (HiRes) image. The observed correlation between the UV and the IR emission suggests that the dust scatters a substantial fraction of the incident UV photons, while absorbing some of the remainder and reemitting this energy in the IR. We have compared the UIT images with the Einstein X-ray images, IRAS HiRes images, and ground-based CCD fields in [O III] lambda-5007, H-alpha, B, R, U, and Stromgren u. This comparison is extremely useful in identifying and studying large H II regions, stellar windblown cavities, and extended large-scale filaments which are delineated largely by the expansion of supernova shells.