New insight into the massive eccentric binary HD 165052: self-consistent orbital solution, apsidal motion, and fundamental parameters

Abstract

HD165052 is a short-period massive eccentric binary system that undergoes apsidal motion. As the rate of apsidal motion is directly related to the internal structure constants of the binary components, its study allows to get insight into the internal structure of the stars. We use medium- and high-resolution spectroscopic observations of HD165052 to provide constraints on the fundamental properties of the binary system and the evolutionary state of its components. We apply a spectral disentangling code to reconstruct artefact-free spectra of the individual stars and derive the radial velocities (RVs) at the times of the observations. We perform the first analysis of the disentangled spectra with the non-LTE model atmosphere code CMFGEN to determine the stellar properties. We derive the first self-consistent orbital solution of all existing RV data, including those reported in the literature, accounting for apsidal motion. We build, for the very first time, dedicated stellar evolution tracks with the Clés code requesting the theoretical effective temperatures and luminosities to match those obtained from our spectroscopic analysis. The binary system HD165052, consisting of an O6.5V((f)) primary and an O7V((f)) secondary, displays apsidal motion at a rate of (11.30+0.64-0.49)$°$yr${}^{-1}$. Evolutionary masses are compared to minimum dynamical masses to constrain the orbital inclination. Evolutionary masses Mev,P=24.8$\pm$1.0M${}_{\odot }$ and Mev,S=20.9$\pm$1.0M${}_{\odot }$ and radii Rev,P=7.0+0.5-0.4R${}_{\odot }$ and Rev,S=6.2+0.4-0.3R${}_{\odot }$ are derived, and the inclination is constrained to 22.1$°\le i\le 23.3°$. Theoretical apsidal motion rates, derived assuming an age of 2.0+/-0.5 Myr for the binary, are in agreement with the observational determination. The agreement with theoretical apsidal motion rates enforces the inferred values of the evolutionary stellar masses and radii.

17 pages. arXiv admin note: text overlap with arXiv:2205.11207

References in corpus (12)

• Binary interaction dominates the evolution of massive stars
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• UBVJHK synthetic photometry of Galactic O stars
• CLES, Code Liegeois d'Evolution Stellaire
• Fitting the young main-sequence; distances, ages and age spreads
• Observational Evidence for Tidal Interaction in Close Binary Systems
• The dependence of convective core overshooting on stellar mass: reality check, and additional evidence
• The Struve-Sahade effect in the optical spectra of O-type binaries I. Main-sequence systems
• Massive heartbeat stars from TESS. I. TESS sectors 1-16
• Analysis of apsidal motion in eclipsing binaries using TESS data II. A test of internal stellar structure}
• Apsidal motion in massive eccentric binaries in NGC 6231: The case of HD 152219
• The Massive Binary System 9 Sgr Revisited: New Insights into Disentangling Methods