Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z

J. I. Villaseñor; H. Sana; L. Mahy; T. Shenar; J. Bodensteiner; N. Britavskiy; D. J. Lennon; M. Moe; L. R. Patrick; M. Pawlak; D. M. Bowman; P. A. Crowther; S. E. de Mink; K. Deshmukh; C. J. Evans; M. Fabry; M. Fouesneau; G. Holgado; N. Langer; J. Maíz Apellániz; I. Mandel; L. M. Oskinova; D. Pauli; V. Ramachandran; M. Renzo; H. W. Rix; D. F. Rocha; A. A.C. Sander; F. R.N. Schneider; K. Sen; S. Simón-Díaz; J. Th van Loon; S. Toonen; J. S. Vink

doi:10.1051/0004-6361/202453166

Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z

J. I. Villaseñor, H. Sana, L. Mahy, T. Shenar, J. Bodensteiner, N. Britavskiy, D. J. Lennon, M. Moe, L. R. Patrick, M. Pawlak, D. M. Bowman, P. A. Crowther, S. E. de Mink, K. Deshmukh, C. J. Evans, M. Fabry, M. Fouesneau, G. Holgado, N. Langer, J. Maíz ApellánizI. Mandel, L. M. Oskinova, D. Pauli, V. Ramachandran, M. Renzo, H. W. Rix, D. F. Rocha, A. A.C. Sander, F. R.N. Schneider, K. Sen, S. Simón-Díaz, J. Th van Loon, S. Toonen, J. S. Vink

School of Physics and Astronomy

Tel Aviv University

Research output: Contribution to journal › Article › peer-review

Abstract

Early B-type stars with initial masses between 8 and 15 M are frequently found in multiple systems, as is 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 < 10 au) fraction or orbital-period distributions between the Milky Way’s solar metallicity (Z) and that of the LMC (Z = 0.5 Z). 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 = 0.2 Z) 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_mult^obs = 50 ± 3%. Using Monte Carlo simulations to account for observational biases, we infer an intrinsic close-binary fraction of f_mult = 80 ± 8%. This fraction reduces to ∼55% when increasing our RV threshold from 20 to 80 km s⁻¹; however, an independent Markov chain Monte Carlo analysis of the peak-to-peak RV distribution (∆RV_max) confirms a high multiplicity fraction of f_mult = 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.

Original language	English
Article number	A41
Journal	Astronomy and Astrophysics
Volume	698
DOIs	https://doi.org/10.1051/0004-6361/202453166
State	Published - 1 Jun 2025

Keywords

Magellanic Clouds
binaries: close
binaries: spectroscopic
stars: early-type
stars: massive

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/202453166

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Villaseñor, 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., ... Vink, J. S. (2025). Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z. Astronomy and Astrophysics, 698, Article A41. https://doi.org/10.1051/0004-6361/202453166

@article{009056a419254fcc97dcb5b3925da43a,

title = "Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z",

abstract = "Early B-type stars with initial masses between 8 and 15 M are frequently found in multiple systems, as is 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 < 10 au) fraction or orbital-period distributions between the Milky Way{\textquoteright}s solar metallicity (Z) and that of the LMC (Z = 0.5 Z). 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 = 0.2 Z) 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 fmultobs = 50 ± 3\%. Using Monte Carlo simulations to account for observational biases, we infer an intrinsic close-binary fraction of fmult = 80 ± 8\%. This fraction reduces to ∼55\% when increasing our RV threshold from 20 to 80 km s−1; however, an independent Markov chain Monte Carlo analysis of the peak-to-peak RV distribution (∆RVmax) confirms a high multiplicity fraction of fmult = 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{\textquoteright}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.",

keywords = "Magellanic Clouds, binaries: close, binaries: spectroscopic, stars: early-type, stars: massive",

author = "Villase{\~n}or, \{J. I.\} and H. Sana and L. Mahy and T. Shenar and J. Bodensteiner and N. Britavskiy and Lennon, \{D. J.\} and M. Moe and Patrick, \{L. R.\} and M. Pawlak and Bowman, \{D. M.\} and Crowther, \{P. A.\} and \{de Mink\}, \{S. E.\} and K. Deshmukh and Evans, \{C. J.\} and M. Fabry and M. Fouesneau and G. Holgado and N. Langer and \{Ma{\'i}z Apell{\'a}niz\}, J. and I. Mandel and Oskinova, \{L. M.\} and D. Pauli and V. Ramachandran and M. Renzo and Rix, \{H. W.\} and Rocha, \{D. F.\} and Sander, \{A. A.C.\} and Schneider, \{F. R.N.\} and K. Sen and S. Sim{\'o}n-D{\'i}az and \{van Loon\}, \{J. Th\} and S. Toonen and Vink, \{J. S.\}",

note = "Publisher Copyright: {\textcopyright} The Authors 2025.",

year = "2025",

month = jun,

day = "1",

doi = "10.1051/0004-6361/202453166",

language = "الإنجليزيّة",

volume = "698",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Villaseñor, JI, Sana, H, Mahy, L, Shenar, T, Bodensteiner, J, Britavskiy, N, Lennon, DJ, Moe, M, Patrick, LR, Pawlak, M, Bowman, DM, Crowther, PA, de Mink, SE, Deshmukh, K, Evans, CJ, Fabry, M, Fouesneau, M, Holgado, G, Langer, N, Maíz Apellániz, J, Mandel, I, Oskinova, LM, Pauli, D, Ramachandran, V, Renzo, M, Rix, HW, Rocha, DF, Sander, AAC, Schneider, FRN, Sen, K, Simón-Díaz, S, van Loon, JT, Toonen, S & Vink, JS 2025, 'Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z', Astronomy and Astrophysics, vol. 698, A41. https://doi.org/10.1051/0004-6361/202453166

TY - JOUR

T1 - Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z

AU - Villaseñor, J. I.

AU - Sana, H.

AU - Mahy, L.

AU - Shenar, T.

AU - Bodensteiner, J.

AU - Britavskiy, N.

AU - Lennon, D. J.

AU - Moe, M.

AU - Patrick, L. R.

AU - Pawlak, M.

AU - Bowman, D. M.

AU - Crowther, P. A.

AU - de Mink, S. E.

AU - Deshmukh, K.

AU - Evans, C. J.

AU - Fabry, M.

AU - Fouesneau, M.

AU - Holgado, G.

AU - Langer, N.

AU - Maíz Apellániz, J.

AU - Mandel, I.

AU - Oskinova, L. M.

AU - Pauli, D.

AU - Ramachandran, V.

AU - Renzo, M.

AU - Rix, H. W.

AU - Rocha, D. F.

AU - Sander, A. A.C.

AU - Schneider, F. R.N.

AU - Sen, K.

AU - Simón-Díaz, S.

AU - van Loon, J. Th

AU - Toonen, S.

AU - Vink, J. S.

PY - 2025/6/1

Y1 - 2025/6/1

N2 - Early B-type stars with initial masses between 8 and 15 M are frequently found in multiple systems, as is 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 < 10 au) fraction or orbital-period distributions between the Milky Way’s solar metallicity (Z) and that of the LMC (Z = 0.5 Z). 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 = 0.2 Z) 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 fmultobs = 50 ± 3%. Using Monte Carlo simulations to account for observational biases, we infer an intrinsic close-binary fraction of fmult = 80 ± 8%. This fraction reduces to ∼55% when increasing our RV threshold from 20 to 80 km s−1; however, an independent Markov chain Monte Carlo analysis of the peak-to-peak RV distribution (∆RVmax) confirms a high multiplicity fraction of fmult = 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.

AB - Early B-type stars with initial masses between 8 and 15 M are frequently found in multiple systems, as is 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 < 10 au) fraction or orbital-period distributions between the Milky Way’s solar metallicity (Z) and that of the LMC (Z = 0.5 Z). 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 = 0.2 Z) 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 fmultobs = 50 ± 3%. Using Monte Carlo simulations to account for observational biases, we infer an intrinsic close-binary fraction of fmult = 80 ± 8%. This fraction reduces to ∼55% when increasing our RV threshold from 20 to 80 km s−1; however, an independent Markov chain Monte Carlo analysis of the peak-to-peak RV distribution (∆RVmax) confirms a high multiplicity fraction of fmult = 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.

KW - Magellanic Clouds

KW - binaries: close

KW - binaries: spectroscopic

KW - stars: early-type

KW - stars: massive

UR - http://www.scopus.com/inward/record.url?scp=105007163606&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/202453166

DO - 10.1051/0004-6361/202453166

M3 - مقالة

SN - 0004-6361

VL - 698

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A41

ER -

Binarity at LOw Metallicity (BLOeM) Enhanced multiplicity of early B-type dwarfs and giants at Z = 0.2 Z

Abstract

Keywords

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