Evidence for outburst in the shell star 17 Lep derived from ultraviolet spectra.

Abstract

Seven high resolution spectra of the primary of the binary system 17 Lep are analyzed. Variations in the shell lines that dominate the ultraviolet spectrum are found. Two of the spectra show shortward enlargements of the strongest shell lines, reaching a FWHM up to 250 km s^-1, and the weakening of the weakest lines. Our suggestion is that two outbursts like those found in the visible are observed. The other spectra having absorption with FWHM up to 150 km s^-1 may correspond to normal phases. In both cases the shell lines cover velocity ranges systematically larger than those observed in the visible. The Mg II resonance lines have typical P-Cygni profiles. Variations in the emission line profiles are detected which are apparently uncorrelated with the behaviour of the absorption line.