A study of the interacting binary V393Scorpii

Abstract

We present high-resolution J-band spectroscopy of V393Sco obtained with the Cryogenic High-Resolution Infrared Echelle Spectrograph (CRIRES) at the ESO Paranal Observatory along with a discussion of archival International Ultraviolet Explorer (IUE) spectra and published broad-band magnitudes. The best fit to the spectral energy distribution outside eclipse gives K for the gainer, for the donor, mag and a distance of pc, although circumstellar material was not considered in the fit. We argue that V393Sco is not a member of the open cluster M7. The shape of the HeI 1083-nm line shows orbital modulations that can be interpreted in terms of an optically thick pseudo-photosphere mimicking a hot B-type star and relatively large equatorial mass loss through the Lagrangian L3 point during long cycle minimum. IUE spectra show several (usually asymmetric) absorption lines from highly ionized metals and a narrow L emission core on a broad absorption profile. The overall behaviour of these lines suggests the existence of a wind at intermediate latitudes. From the analysis of the radial velocities (RVs) we find M₂/M₁ = 0.24 +/- 0.02 and a mass function of f = 4.76 +/- 0.24M. Our observations favour equatorial mass loss rather than high-latitude outflows as the cause for the long variability.