J/A+A/698/A41ivo://CDS.VizieR/J/A+A/698/A41doi:10.26093/cds/vizier/bc-nt/lebCDSVillasenor J.I.Sana H.Mahy L.Shenar T.Bodensteiner J.,Britavskiy N.Lennon D.J.Moe M.Patrick L.R.Pawlak M.Bowman D.M.,Crowther P.A.de Mink S.E.Deshmukh K.Evans C.J.Fabry M.,Fouesneau M.Holgado G.Langer N.Maiz Apellaniz J.Mandel I.,Oskinova L.M.Pauli D.Ramachandran V.Renzo M.Rix H.-W.Rocha D.F.,Sander A.A.C.S.Schneider F.R.N.Sen K.Simon-Diaz S.van Loon J.T.,Toonen S.Vink J.S.2026-08-03T06:55:09Z2025-05-28T09:46:44ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frspectroscopic-binary-starsb-starsradial-velocityEarly B-type stars with initial masses between 8 and 15 solM are frequently found in multiple systems, as evidenced by multi-epoch spectroscopic campaigns in the Milky Way and the Large Magellanic Cloud (LMC). Previous studies have shown no strong metallicity dependence in the close-binary (a<10au) fraction or orbital-period distributions between the Milky Way's solar metallicity (Z_{sun}_) and that of the LMC (Z=0.5Z_{sun}_). However, similar analyses for a large sample of massive stars in more metal-poor environments are still scarce. We focus on 309 early B-type stars (luminosity classes III-V) from the Binarity at LOw Metallicity (BLOeM) campaign, which targeted nearly 1000 massive stars in the Small Magellanic Cloud (SMC, Z=0.2Z_{sun}_) using VLT/FLAMES multi-epoch spectroscopy. By applying binary detection criteria consistent with previous works on Galactic and LMC samples, we identify 153 stars (91 SB1, 59 SB2, 3 SB3) exhibiting significant radial-velocity (RV) variations, resulting in an observed multiplicity fraction of f_obs_=50+/-3. Using Monte Carlo simulations to account for observational biases, we infer an intrinsic close-binary fraction of f_bin_=80+/-8. This fraction reduces to ~55% when increasing our RV threshold from 20 to 80km/s, however, an independent Markov chain Monte Carlo analysis of the peak-to-peak RV distribution ({Delta}RV_max_) confirms a high multiplicity fraction of f_bin_=79+\-5. These findings suggest a possible anti-correlation between metallicity and the fraction of close B-type binaries, with the SMC multiplicity fraction significantly exceeding previous measurements in the LMC and the Galaxy. The enhanced fraction of close binaries at SMC's low metallicity may have broad implications for massive-star evolution in the early Universe. More frequent mass transfer and envelope stripping could boost the production of exotic transients, stripped supernovae, gravitational-wave progenitors, and sustained UV ionising flux, potentially affecting cosmic reionisation. Theoretical predictions of binary evolution under metal-poor conditions will provide a key test of our results.2025A&A...698A..41Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/698/A41CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/AcA/66/421 : Eclipsing binaries in the Magellanic System (Pawlak+, 2016)J/A+A/690/A289 : Binarity at LOw Metallicity (BLOeM). I. (Shenar+, 2024)J/A+A/698/A38 : BLOeM. Oe and Be stars (Bodensteiner+, 2025)J/A+A/698/A39 : BLOeM. BAF-type supergiants (Patrick+, 2025)J/A+A/698/A40 : BLOeM. SMC early B supergiants multiplicity (Britavskiy+ 2025)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/698/A41https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/698/A41http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/698/A41https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/698/A41https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/698/A41http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/698/A41GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/698/A41/tabled1 (Results of RV analysis)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/698/A41/tabled1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/698/A41/tabled1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/698/A41/tabled1?GETtext/xml+votable180.050000true15.20829167-72.082972220.0055555555555555566/33294-33295 33298 33304 33306 33317 333281.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/698/A41?format=asciidefaultJ/A+A/698/A41/tabled1Results of RV analysisrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBLOeMField-ID number (N-NNN)meta.id;meta.maincharGaiaDR3GAIA DR3 IDmeta.idRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainGmagGaia G magnitudemagphot.mag;em.optfloatSpTypeSpectral type and luminosity classsrc.spTypecharn[3/9] Number of epochs available or used in RV determinationmeta.numberintdRVMaximum radial velocity differencekm/sspect.dopplerVeloc;arith.diff;stat.maxfloatdRVsigniDetection significancestat.fit.goodnessfloatBinBinary classificationsrc.classcharPerOrbital perioddtime.periodfloatPersigni[S P NS] Orbital period significance (1)stat.fit.goodnesscharPOGLE? Orbital period from OGLEdtime.perioddoublenullableCommentsCommentsmeta.notecharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/698/A41/tabled2Eclipsing binaries from OGLErecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBLOeMBLOeM field-ID number (BLOeM N-NNN)meta.id;meta.maincharOGLEOGLE identifiermeta.idcharSpTypeSpectral type (1)src.spTypecharImagOGLE I-band magnitude (2)magphot.mag;em.opt.IfloatPerOGLE orbital period (2)dtime.periodfloatTypeOGLE classification (2) (3)src.classcharSimbadSimbad column added by the CDSmeta.ref.urlchar