The newly discovered eclipsing supergiant 22 Vulpeculae.

Abstract

Spectra obtained with the IUE satellite have led to the discovery of a new atmospheric eclipsing binary belonging to the ζ Aurigae class of stars, 22 Vul. This system is unique in that it is the first one found with a G-type primary (G3 Ib-II), while the spectral type of the secondary is the latest (B9) and its period is the shortest (249 days) of any of the classical members of the group. Combined with published optical data, the authors derive system parameters and dimensions. They argue that the secondary is embedded within a strong, dense wind from the primary and demonstrate that at atmospheric eclipse phases the UV spectra have properties similar to the interacting binaries SX Cas and HD 207739.