Active binary R Arae revisited: Bringing the secondary component to light and physical modelling of the circumstellar material

Bakis H., Bakis V., Eker Z., Demircan O.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.458, no.1, pp.508-516, 2016 (SCI-Expanded) identifier identifier


The spectral lines of the secondary component of the active binary system R Ara were uncovered for the first time, which allowed directly to determine the parameters of the spectroscopic orbit. The mass ratio of the system is updated to a new observational value of M-2/M-1 = 0.305 +/- 0.005 which is similar to 20 per cent smaller than the literature value (M-2/M-1 = 0.39). Modelling the reconstructed component spectra yielded the equatorial rotational velocities of the components as nu(rot1) = 202 km s(-1) and nu(rot2) = 73 km s(-1) indicating a very fast rotation (similar to 5 times faster than the synchronous rotation velocity) for the primary and synchronous rotation for the secondary component. The circumstellar material in the system was investigated using the Hipparcossatellite data and the high-resolution (R similar to 41 000) spectral data. According to our model, there is always material transferring from the secondary component on to the primary causing a hot region on its surface. The structural difference between the spectra taken at the same orbital phase but at different epochs proved that the density and the velocity of the transferring material are variable. There are three main trends in the light curve and spectral line variations suggesting the activity cycles for the system, namely quiescent, moderate and, active cycles. It was estimated that the circumstellar material around could be extended to large distances up to 40 R-circle dot from the system.