RS Sagittarii: Revealing the component spectra and the mass transfer


Bakış H., Hilal Yıldız Ö., Bakış V., Yücel G.

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA, cilt.42, ss.114-135, 2025 (SCI-Expanded, Scopus) identifier identifier

Özet

We present an analysis of high-resolution ( $R \sim 48\,000$ ) spectroscopic and photometric data of RS Sgr, a short-period Algol-type binary system. For the first time, precise spectroscopic and absolute parameters of the system have been determined. The primary component is identified as a B3 main-sequence star with an effective temperature of 19 000 K, while the secondary is classified as an A0-type star with a temperature of 9 700 K. The secondary appears to have recently evolved off the main sequence and currently fills its Roche lobe, transferring material through the inner Lagrangian point (L $_1$ ) to the hotter primary component. The H $_\alpha$ emission and absorption features observed in the spectra are attributed to a combination of a low-density circumprimary disk, a gas stream originating from the secondary, and a hot spot formed at the impact site on the primary. The combined analysis of spectroscopic and photometric data yields a system distance of approximately 418 pc, which is consistent with the value derived from GAIA DR3 within the uncertainty limits.