Spectroscopy of the recurrent nova V3890 sagittarii 18 days after the 1990 outburst

Abstract

The spectrum of the recurrent nova V3890 Sgr, obtained from the Vainu Bappu Observatory 18 d after the 1990 outburst maximum, is presented. The nova was in the coronal line phase. The spectrum is similar to that of the recurrent nova RS Oph. An extinction E(B - V) = 1.1 is derived from the B - V colours, and from Balmer and He I line ratios. From the maximum magnitude-rate-of-decline relations for a nova, MV = -8.6 mag is estimated, which places the nova at a distance of about 5 kpc. Balmer line fluxes are used to derive the density, ˜109 cm-3, and the mass of the ejected ionized shell, ˜10-7 Msun. The temperature and radius estimates for the ionizing source are 3 × 105 K and 0.06 Rsun. A helium abundance of 0.23 is estimated. Applying expansion models in which the fast moving nova eject interact with a slow moving pre-outburst wind, we conclude that the eject expanded into an inhomogeneous stellar wind.