| Issue |
A&A
Volume 706, February 2026
|
|
|---|---|---|
| Article Number | A311 | |
| Number of page(s) | 12 | |
| Section | Astrophysical processes | |
| DOI | https://doi.org/10.1051/0004-6361/202555779 | |
| Published online | 18 February 2026 | |
Non-synchronous rotation in massive binary systems
III. Characterizing five binary systems with fast-rotating OB Stars★
1
Instituto de Astrofísica de La Plata, CONICET–UNLP Paseo del Bosque s/n B1900FWA La Plata, Argentina
2
Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata La Plata, Argentina
3
Las Campanas Observatory, Carnegie Observatories Casilla 601 La Serena, Chile
4
Departamento de Astronomía, Universidad de La Serena Av. Cisternas 1200 Norte La Serena, Chile
★★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
2
June
2025
Accepted:
4
January
2026
Context. Among the binary systems discovered by the spectroscopic monitoring of Southern Galactic O and WN stars, or the OWN Survey, several systems exhibit very different line broadening between their components.
Aims. We aim to characterize these binary systems in order to understand the causes behind their markedly different spectral line widths, providing observational clues as to the physical mechanisms at play.
Methods. We used new and archival multi-epoch high-resolution optical spectra for the radial velocity analysis and determined the spectroscopic orbits of both components in five systems: HD 57236, HD 93028, HD 101413, HD 151003, and HD 153426. The physical properties of the individual stellar components were determined through quantitative analysis. Using evolutionary models, we estimated the age of the systems and explored their tidal evolution.
Results. The systems consist of O+O or O+B stars, with minimum masses ranging from ∼6 M⊙ to 21 M⊙, in young, wide, and fairly eccentric orbits (periods from approximately 22 to 977 d and eccentricities of e > 0.14). The primary and secondary components have a projected rotational velocity ratio of up to 1:7 (∼27 and ∼193 km s−1 in the case of HD 93028), similar to previous binary systems in this series, namely HD 93343 and HD 96264A.
Conclusions. The youth and wide orbits of the systems indicate that the non-synchronous rotational nature of their components is a consequence of the stellar formation process, rather than a result of past binary interactions. While the role of binary interactions may be predominant in many cases, it is not a necessary condition to explain the entire observed population of fast rotators.
Key words: stars: fundamental parameters / stars: massive / stars: rotation
Based on data acquired at Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan. Also based on observations gathered at Las Campanas (Carnegie Observatories) and ESO-La Silla Observatory.
© The Authors 2026
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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