Ultraviolet study of the active interacting binary star R Arae using archival IUE data
Sahade, Jorge; Guinan, Edward F.; Reed, Phillip A.; Reichart, Daniel E.; Ivarsen, Kevin M.; Nysewander, Melissa C.; Kondo, Yoji; McCluskey, George E., Jr.; Giménez, Alvaro; Caton, Daniel B.
United States, Argentina, Spain
Abstract
The eclipsing and strongly interacting binary star system R Arae (HD 149730) is in a very active and very short-lived stage of its evolution. R Ara consists of a B9V primary and an unknown secondary. We have collected the International Ultraviolet Explorer (IUE) archival data on R Ara, with most of the data being studied for the first time. There are 117 high-resolution IUE spectra taken in 1980, 1982, 1985, 1989 and 1991. We provide photometric and spectroscopic evidence for mass transfer and propose a geometry for the accretion structure. We use colour-scale radial velocity plots to view the complicated behaviour of the blended absorption features and to distinguish the motions of hotter and cooler regions within the system. We observed a primary eclipse of R Ara in 2008 and have verified that its period is increasing. A model of the system and its evolutionary status is presented.