Modelling of the B-type binaries CW Cep and U Oph: A critical view on dynamical masses, core boundary mixing, and core mass

Abstract

Context: Intermediate-Mass stars are often overlooked as they are not supernova progenitors but still host convective cores and complex atmospheres which require computationally expensive treatment. Due to this, there is a general lack of such stars modelled by state of the art stellar structure and evolution codes. Aims: This paper aims to use high-quality spectroscopy to update the dynamically obtained stellar parameters and produce a new evolutionary assessment of the bright B0.5+B0.5 and B5V+B5V binary systems CW Cep and U Oph. Methods: We use new spectroscopy obtained with the Hermes spectrograph to revisit the photometric binary solution of the two systems. The updated mass ratio and effective temperatures are incorporated to obtain new dynamical masses for the primary and secondary. With these, we perform isochrone-cloud based evolutionary modelling to investigate the core properties of these stars. Results: We report the first abundances for CW Cep and U Oph as well as report an updated dynamical solution for both systems. We find that we cannot uniquely constrain the amount of core boundary mixing in any of the stars we consider. Instead, we report their core masses and compare our results to previous studies. Conclusions: We find that the per-cent level precision on fundamental stellar quantities are accompanied with core mass estimates to between ~ 5-15%. We find that differences in analysis techniques can lead to substantially different evolutionary mode

15 pages, 7 figures, two appendices with 4 figures each. Accepted for publication in Astronomy & Astrophysics

References in corpus (15)

• The Transiting Exoplanet Survey Satellite
• Astrophysics Source Code Library
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• BONNSAI: a Bayesian tool for comparing stars with stellar evolution models
• An asteroseismic study of the beta Cephei star theta Ophiuchi: constraints on global stellar parameters and core overshooting
• Binary Asteroseismic Modelling: isochrone-cloud methodology and application to Kepler gravity-mode pulsators
• The Most Massive Heartbeat: An In-depth Analysis of ι Orionis
• Statistical errors and systematic biases in the calibration of the convective core overshooting with eclipsing binaries. A case study: TZ Fornacis
• KIC 3749404: A heartbeat Star with Rapid Apsidal Advance Indicative of a Tertiary Component
• Chemical evolution of high-mass stars in close binaries. I. The eclipsing binary V453 Cygni
• Physical properties and CNO abundances for high-mass stars in four main-sequence detached eclipsing binaries: V478 Cyg, AH Cep, V453 Cyg and V578 Mon
• Tracing CNO exposed layers in the Algol-type binary system u Her
• A remarkable change of the spectrum of the magnetic Of?p star HD 148937 reveals evidence of an eccentric, high-mass binary
• Accurate stellar parameters and distance to two evolved eclipsing binary systems, OGLE-BLG-ECL-123903 and OGLE-BLG-ECL-296596, towards the Galactic bulge
• An X-ray Study of Two B+B Binaries: AH Cep and CW Cep

Cited by in corpus (6)

• The mass discrepancy in intermediate- and high-mass eclipsing binaries: the need for higher convective core masses
• Analysis of apsidal motion in eclipsing binaries using TESS data II. A test of internal stellar structure}
• A comparison of the dynamical and model-derived parameters of the pulsating eclipsing binary KIC9850387
• Isochrone-cloud fitting of the extended Main-Sequence Turn-Off of young clusters
• Mon-735: A new low-mass pre-main sequence eclipsing binary in NGC 2264
• $\beta$ Cephei Pulsations in the High-mass Eclipsing System CW Cephei