Eze, Christian I. ; Handler, Gerald ; Kahraman Aliçavuş, Filiz ; Pawar, Tilaksingh ; De Cat, Peter

submitted to Astronomy & Astrophysics (2026)

Abstract: Eclipsing binaries are veritable laboratories for the study of stellar structure and evolution. The dynamical properties (e.g. mass and radius) inferred from eclipsing binary modelling coupled with asteroseismic masses offer a unique opportunity to probe stellar evolution models. Spectroscopy characterises the stellar envelope and plays a key role in estimating more accurate dynamical parameters, as it provides invaluable priors for the eclipsing light curve modelling. In this paper, 13 apparently eclipsing single-lined spectroscopic binaries with massive primary components are spectroscopically analysed to derive the orbital and stellar parameters, and infer the possible relation between orbital and stellar parameters. The systems were observed using SALT HRS, HERMES, CHIRON and a spectrograph at Skalnate Pleso Observatory (SPO). The radial velocities are estimated, orbital elements are fitted, atmospheric solutions are measured, and absolute parameters are derived. The rotation as well as circularisation and synchronisation of the systems are also investigated and the general properties of the sample are discussed. The sample shows 1 slow rotator, 3 circularised and synchronised fast rotating systems, as well as 6 circular and 3 eccentric systems with asynchronous fast rotation. They have a primary mass range of 8.7(9) M to 15.6(9) M and effective temperature of 22000(1000) K to 28000(1000) K. The secondary components appear to cut across a wide mass spectrum ranging from low-mass to intermediate mass systems. The eccentricity of the systems shows certain trends with the projected rotational velocity (v sin i) although there is no universal correlation between them. Also, there could be circularisation without co-rotation or synchronisation even for circularised short-period close binary systems

Keyword(s): Binaries: eclipsing ; Binaries: spectroscopic ; Stars: massive