Inefficient Accretion by the DA2 White Dwarf in V471 Tauri

Abstract

The results are reported of an analysis of eight-high-resolution International Ultraviolet Explorer (IUE) short-wavelength primary spectra of V471 Tauri, an eclipsing-spectroscopic, precataclysmic binary in the Hyades. The coaddition in velocity space of regions surrounding principle high- and low-excitation ion species on a common velocity scale was used. Identifiable lines were found to fall into three categories: interstellar absorption in the line of sight to the Hyades cluster; broad features due to absorption by the stellar wind from the K2 dwarf; and narrow high-velocity circumbinary absorption independent of orbital phase. The white dwarf in V471 Tauri is estimated to have accreted some 40,000 times more material than the determined upper limits. It is proposed that the barrier presented by the white drawf's rotating magnetosphere reduces accretion from the K2V stellar wind to levels which are undetectable with the IUE satellite.