Feige 24 - A very hot white dwarf

Abstract

OAO-2 ultraviolet photometry of the composite spectrum white dwarf Feige 24 is compared with model atmospheres to derive an effective temperature of 70,000 (+20,000, -15,000) K. The distance to this star is estimated to be 90 (+55, -31) pc if the cool component is assumed to be a main-sequence star with a red and near-infrared energy distribution that is normal for its spectral type. The derived characteristics of Feige 24 are compatible with its identification as the extreme-ultraviolet source observed by Margon et al.