Evidence for a change of composition in the giant component of RS Oph after the 1985 outburst

Abstract

The most recent outburst of the recurrent nova RS Oph occurred in 1985 January. K-band spectra were acquired of this object shortly after outburst, and on two occasions in 1992. The strength of the first-overtone CO absorption features has declined substantially over this 7-year period. We discuss a mechanism whereby the outburst contaminated the secondary with excess carbon, which has subsequently been convected away. We show that this mechanism is consistent with the observed data. Such contamination must have a major impact on the evolution of the secondary in nova systems.