Line profiles from supernovae.

Abstract

The location and mechanism of 120-200-nm emissions from supernovae are investigated theoretically, and the results are applied to IUE observations of SN 1979c reported by Panagia et al. (1980). Analytical expressions are obtained for line profiles originating in the expanding photosphere behind the shock wave (using the two-level approximation) and in the circumstellar gas (taking negative velocity gradients and coupling into account). The results of numerical calculations are compared with the SN 1979c profiles in graphs, and it is shown that the supernova shock provides X-ray heating of the outer photosphere which leads to the emission of UV radiation from a geometrically thin layer having density greater than 10 to the 9th/cu cm and located near the photosphere rather than in the circumstellar gas.