Results from the Ultraviolet Imaging Telescope

We present images from the Ultraviolet Imaging Telescope (UIT) of six starburst, interacting, or Seyfert galaxies, and of a galactic supernova remnant. We investigate the star formation history of the various galaxies by using UV color-color diagrams. The star formation rates, estimated by the FUV emission, range from a few tenths to a few solar masses per year. We find that the time since last significant star formation varies by over an order of magnitude among the different galaxies. Face on galaxies are brighter in the far ultraviolet than the edge on galaxies; we interpret this as due to dust in the line of sight in the edge of galaxies quenching the UV photons.; In addition to the general trends mentioned above, analysis of the individual galaxies show a wide range of interesting phenomena. We find that the mid ultraviolet emission in M82 is bright along the major axis, and we observe a MUV plume coinciding with H{dollar}alpha{dollar} filaments. We interpret this MUV plume as being part of a reflection nebula in which dust in the southern portion of M82 is forward scattered into the line of sight. The anisotropic scattering nature of dust would increase the surface brightness of forward scattered light as compared with backward scattered light. The observed colors of M82 are very red, which we interpret as being heavily reddened by the large amounts of dust internal to the galaxy. This dust would absorb and scatter the FUV photons that would be produced in the central starburst in the center of M82. We measure the dust reddening law in two places in M82, and neither reddening curve is consistent with the mean galactic reddening curve.; The galaxy NGC4151 exhibits small spiral arms, which we interpret in terms of active star formation in a spiral density wave. We find that NGC4151 more closely resembles spirals such as M74 and M81 than it does the Seyfert NGC1068. The interacting pair NGC2992/2993 show large differences in their flux in the FUV. NGC2993 is seen face on and has UV colors indicative of star formation in the last 200 Myr. NGC2992 is more edge on, and has much redder colors, indicative of dust reddening. The starburst galaxy NGC2146 has UV colors very similar to M82, which we again interpret as being heavily reddened by dust. We obtain an extinction law in the main dust lane of NGC2146 that is indictive of the dust being more forward scattering than the mean galactic reddening law. UGC6697 shows evidence for recent star formation, consistent with an interaction with the intra-cluster medium of Abell 1367.