Coronal Element Abundances of the Post–Common‐Envelope Binary V471 Tauri withASCA

Abstract

We report on ASCA observations of the coronally active companion star in the post-common envelope binary V471 Tauri. Evolutionary calculations indicate that there should be no peculiar abundances on the companion star resulting from the common envelope epoch. Indeed, we find no evidence for peculiar abundances, although uncertainties are high. We find that a single-temperature plasma model does not fit the data. Two-temperature models with decoupled elemental abundances suggest that Fe is underabundant compared to the Hyades photospheric mean. In the absence of a measurement of photospheric Ne abundance in the cluster, we find Ne is overabundant compared to the solar photospheric value. This is indicative of the inverse first ionization potential effect. Differences between coronal and photospheric abundances are believed to result from the fractionation of ionized and neutral material in the upper atmosphere of the star.