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Lookup NU author(s): Federica Nardini, Dr Dominic BowmanORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Multiplicity among massive stars represents a major uncertainty in stellar evolution theory, because the extra physical processes that it introduces significantly impact each star’s structure. While multiplicity of O-type stars is fairly well constrained, for B-type stars it is not. B-type stars are more common and have longer lifetimes, thus providing an opportunity to characterize multiplicity at different ages. Moreover, young open clusters are advantageous for studying coeval and chemically homogeneous environments. Using a multi-epoch spectroscopic campaign with the High Efficiency and Resolution Mercator Echelle Spectrograph, we determine multiplicity properties and rotation rates of 74 B-type stars in 4 Galactic open clusters: h and chi Persei, NGC 457, NGC 581, and NGC 1960. We measure radial velocities with a cross-correlation method and determine tentative orbital solutions for 26 of the 28 identified binaries. We detect several Be stars, five of them being members of binary systems. We correct the observed binary fractions for observational biases and determine an average intrinsic binary fraction of 79 per cent. The consistency in binary fraction among the four clusters, which are between 15 and 30 Myr, suggests a reasonably homogeneous binary fraction across this age range. We used TLUSTY atmosphere models to determine the projected rotational velocities, with an average value of 240 km/s for both single and binary systems. Whereas, the Be stars show higher velocities between 200 and 360 km/s.
Author(s): Nardini F, Bodensteiner J, Sana H, Mahy L, Deshmukh K, Bowman DM
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2025
Volume: 540
Issue: 3
Pages: 2009–2030
Print publication date: 05/06/2025
Online publication date: 16/05/2015
Acceptance date: 12/05/2015
Date deposited: 24/04/2026
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/staf809
DOI: 10.1093/mnras/staf809
Data Access Statement: Data products that support the results in this paper are publicly available via the Zenodo repository: 10.5281/zenodo.14999884. The Gaia data used in this work are publicly available via the Gaia website: https://gea.esac.esa.int/archive/. The Padova data base of stellar evolutionary tracks and isochrones is publicly available via the website https://stev.oapd.inaf.it/cgi-bin/cmd.
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