Year: 2026
Type: article
Abstract: The Binarity at LOw Metallicity (BLOeM) survey is an ESO large programme designed to obtain multi-epoch spectroscopy for 929 massive stars in the Small Magellanic Cloud (SMC). It will provide binary fractions and orbital configurations of binary systems and search for dormant black hole binary candidates (OB+BH). We present projected rotational velocities (v sin i) of all sources, and, using the multiplicity properties presented in previous papers, we derive the v sin i distributions of apparent single stars, single-lined spectroscopic (SB1) binaries, and SB2 systems. We identify a locus in the Hertzsprung-Russell diagram where rotational velocities decrease significantly; we interpret this feature as broadly corresponding to the terminal-age main sequence. The main-sequence cohort is distinguished by a broad range of v sin i values, but with a strong peak in the distribution in the range 30–60 km s−1, which is close to the resolution limit of ∼30 km s−1, indicating the presence of many upper limits. Sources in this low v sin i peak are distributed throughout the main sequence and are also present in the SB1 sample, though less prominent than in the single-star distribution. A preliminary analysis of the lowest v sin i cohort, which includes SB1 systems, implies that roughly one-third may be nitrogen rich, and we speculate that this cohort is a mix of pristine single stars, long-period binaries, and merger products. The SB2 systems appear to be mostly short-period binaries in synchronous rotation, and their v sin i estimates are distributed around a mean value of ∼140 km s−1. Higher v sin i sources are also present in the single and SB1 systems, all of which have a tail to higher v sin i values. This is consistent with tidal and mass-transfer effects. The supergiants, with a few exceptions, have low v sin i, and the bulk of these systems is essentially unresolved at the current spectral resolution (∼30 km s−1).
Authors: D. J. Lennon, S. R. Berlanas, A. Herrero, N. Britavskiy, P. L. Dufton, N. Langer, H. Jin, A. Schootemeijer, A. Menon, J. Bestenlehner, P. Crowther, J. S. Vink, J. Bodensteiner, T. Shenar, K. Deshmukh, J. I. Villaseñor, L. Patrick, F. Najarro, A. de Koter, L. Mahy, D. M. Bowman, A. Bobrick, C. J. Evans, M. Gull, G. Holgado, Z. Katabi, J. Kubát, P. Marchant, D. Pauli, M. Pawlak, M. Renzo, D. F. Rocha, A. A. C. Sander, T. Sayada, S. Simón-Díaz, M. Stoop, R. Valli, C. Wang, X.-T. Xu
Institutions: Columbia University, University of Bonn, Max Planck Institute for Astrophysics, University of Sheffield, Armagh Observatory & Planetarium, University of Amsterdam, Tel Aviv University, KU Leuven, Queen's University Belfast, Max Planck Institute for Astronomy, Consejo Superior de Investigaciones Científicas, Centro de Astrobiología, Newcastle University, Australian Research Council, ARC Centre of Excellence for Gravitational Wave Discovery, Monash University, Space Telescope Science Institute, European Space Agency, California Institute of Technology, Carnegie Institution for Science, Carnegie Observatories, Czech Academy of Sciences, Astronomical Institute, Ghent University, Lund University, University of Arizona, Laboratório Nacional de Astrofísica, Heidelberg University, Nanjing University, Shanghai Jiao Tong University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Comunidad de Madrid, Government of the United Kingdom, UK Research and Innovation, Ministerio de Ciencia, Innovación y Universidades, European Commission, Deutsche Forschungsgemeinschaft, Fonds Wetenschappelijk Onderzoek, Israel Science Foundation, Ministerio de Ciencia e Innovación, Bundesministerium für Wirtschaft und Energie, Fundación Bancaria Caixa d'Estalvis i Pensions de Barcelona, HORIZON EUROPE Framework Programme, Australian Research Council, European Regional Development Fund, Agencia Estatal de Investigación, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, HORIZON EUROPE European Research Council
Awards: G1069964796, G1255325603, G1513912400, G1750626284, G2290189609, G2309174360, G2660406951, G2858269097, G3326551379, G3398237449, G3480869486, G3803561910, STARs as GRAvitational wave Source Progenitors, G4140491619, G434337789, G4689434848, G483893733, G4944594896, G5080475149, G5099673792, G5132640529, Massive-binary EvoluTion Across the metallicity Ladder, G5955501538, G6033112984, Entschlüsselung der Grundpfeiler unseres Universums: Anwendung und Entwicklung von Sternatmosphären der nächsten Generation, ARC Centre of Excellence for Gravitational Wave Discovery, G6744423155, G6764146023, Kavli Institute for Theoretical Physics, G7084143925, G7135376007, G7254781640, G7685134749, G7731791180, G7801961494, G7805626310, Understanding mixing and chemical enrichment in massive stars, G8278124175, G871455044, G8920660035, Revolutionizing spectral synthesis: From isolated massive stars to unresolved stellar populations in the Early Universe
OpenAlex ID: W7133363458
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