Ultraviolet spectroscopy of the recurrent nova U SCO during outburst.
Gallagher, J. S.; Williams, R. E.; Truran, J. W.; Starrfield, S. G.; Sparks, W. M.; Ney, E. P.
United States, United Kingdom
Abstract
Observations of the recurrent nova U Sco during the 1979 outburst are presented, and the spectral evolution is found to differ from that of other recurrent novas. Spectra are dominated by emission lines, and the strong forbidden-line emission characteristic is conspicuously absent. A method to determine masses of nova shells is outlined, and an analysis of the emission lines shows an enrichment in N relative to C and O, and that the nova ejecta are rich in He relative to H. Optical spectra of U Sco obtained following its return to quiescence show predominantly He II emission lines, which suggests an enrichment of the preoutburst gas in He, and thus the presence of a highly evolved companion.