The chemical composition of IK Pegasi

Abstract

A detailed abundance analysis of the pulsating A-type star IK Peg A is presented. It is found that the Ca and Sc abundances are approximately solar and the Fe-group elements slightly enhanced. Hence, IK Peg A is not a classical Am star, but the results are not inconsistent with its spectroscopic classification as a marginal Am star. The presence of a massive white dwarf companion (IK Peg B) indicates that the binary system has previously undergone a common envelope phase. Enhancements of Ba and Sr are found, which may be evidence of mass transfer from the white dwarf progenitor during this common envelope phase. This, however, is purely speculative, since the abundance anomalies may be explained by radiative diffusion processes operating in the atmosphere of IK Peg A, even though it is undergoing small-amplitude pulsations. It is suggested that IK Peg A is a hot member of the F str λ4077 stars.