Ultraviolet Study of the Active Interacting Binary Star R Arae using Archival IUE Data

TL;DR

This study analyzes archival ultraviolet spectra of the active binary star R Arae, revealing mass transfer, accretion structures, and period changes, providing insights into its evolutionary stage.

Contribution

It presents new spectroscopic and photometric evidence of mass transfer and models the accretion structure and evolution of R Arae using archival IUE data.

Findings

Detected mass transfer and accretion structures.

Confirmed period increase of the binary system.

Provided a model for the system's evolutionary status.

Abstract

The eclipsing and strongly interacting binary star system R Arae (HD149730) 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 behavior 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.