Spectroscopic evolution of Nova LW Serpentis 1978 during its early decline

Abstract

Spectroscopic observations of Nova LW Serpentis have been obtained in 1978 during its decline from V of about 9.0 to V of about 10.2. It is found that the spectrum and its evolution compare well with those of a typical nova, and that the principal absorption could be identified only in the lines of O I 7774, 8446, and in moderate-resolution observations of H-alpha. Features of the spectral evolution noted include the continuous weakening of the near-infrared triplet of Ca II, the brightness of O I 8446 over O I 7774, and the asymmetric nature of the H-alpha emission line. A kinematical model is proposed for the shell of LW Ser consisting of an equatorial ring and a polar cone on the side facing away from the earth.