Ultraviolet observations of starburst and mini-Seyfert galactic nuclei.

Abstract

The high excitation emission line galaxies NGC 1667, NGC 5135, and IC 5135 show activity which, while similar to that of Seyfert 2 galaxies, is 1-2 orders of magnitude smaller. The line and continuum emission is in all three cases more extended than would correspond to a point source. In addition to showing such Seyfert-like characteristics as broad, low contrast wings in the Lyman-alpha profiles and unusual strengths in the emission lines of such high ionization species as He II, NGC 5135 and IC 5135 show starburst characteristics in their UV spectra, with P Cygni profiles that furnish direct evidence of the presence of very massive and hot O stars in their nuclei. It is suggested that they may be galaxies undergoing the transition from the starburst stage to the mini-Seyfert stage.