---
OA_place: publisher
OA_type: hybrid
_id: '18492'
abstract:
- lang: eng
  text: 'Surveys in the Milky Way and Large Magellanic Cloud have revealed that the
    majority of massive stars will interact with companions during their lives. However,
    knowledge of the binary properties of massive stars at low metallicity, and therefore
    in conditions approaching those of the Early Universe, remain sparse. We present
    the Binarity at LOw Metallicity (BLOeM) campaign, an ESO large programme designed
    to obtain 25 epochs of spectroscopy for 929 massive stars in the Small Magellanic
    Cloud, allowing us to probe multiplicity in the lowest-metallicity conditions
    to date (Z = 0.2 Z⊙). BLOeM will provide (i) the binary fraction, (ii) the orbital
    configurations of systems with periods of P ≲ 3 yr, (iii) dormant black-hole binary
    candidates (OB+BH), and (iv) a legacy database of physical parameters of massive
    stars at low metallicity. Main sequence (OB-type) and evolved (OBAF-type) massive
    stars are observed with the LR02 setup of the GIRAFFE instrument of the Very Large
    Telescope (3960–4570 Å resolving power R = 6200; typical signal-to-noise ratio(S/N)
    ≈70–100). This paper utilises the first nine epochs obtained over a three-month
    time period. We describe the survey and data reduction, perform a spectral classification
    of the stacked spectra, and construct a Hertzsprung-Russell diagram of the sample
    via spectral-type and photometric calibrations. Our detailed classification reveals
    that the sample covers spectral types from O4 to F5, spanning the effective temperature
    and luminosity ranges 6.5 ≲ Teff/kK ≲ 45 and 3.7 < log L/L⊙ < 6.1 and initial
    masses of 8 ≲ Mini ≲ 80 M⊙. The sample comprises 159 O-type stars, 331 early B-type
    (B0–3) dwarfs and giants (luminosity classes V–III), 303 early B-type supergiants
    (II–I), and 136 late-type BAF supergiants. At least 82 stars are OBe stars: 20
    O-type and 62 B-type (13% and 11% of the respective samples). In addition, the
    sample includes 4 high-mass X-ray binaries, 3 stars resembling luminous blue variables,
    2 bloated stripped-star candidates, 2 candidate magnetic stars, and 74 eclipsing
    binaries.'
acknowledgement: 'The research leading to these results has received funding from
  the European Research Council (ERC) under the European Union’s Horizon 2020 research
  and innovation programme (grant agreement numbers 772225: MULTIPLES). PAC and JMB
  are supported by the Science and Technology Facilities Council research grant ST/V000853/1
  (PI. V. Dhillon). DMB gratefully acknowledges support from UK Research and Innovation
  (UKRI) in the form of a Frontier Research grant under the UK government’s ERC Horizon
  Europe funding guarantee (SYMPHONY; PI Bowman; grant number: EP/Y031059/1), and
  a Royal Society University Research Fellowship (PI Bowman; grant number: URF\R1\231631).
  ZK acknowledges support from JSPS Kakenhi Grant-in-Aid for Scientific Research (23K19071).
  IM acknowledges support from the Australian Research Council (ARC) Centre of Excellence
  for Gravitational Wave Discovery (OzGrav), through project number CE230100016. AACS,
  VR, RRL, and MBP are funded by the Deutsche Forschungsgemeinschaft (DFG, German
  Research Foundation) in the form of an Emmy Noether Research Group – Project-ID
  445674056 (SA4064/1-1, PI Sander). GGT and JJ are supported by the German Deutsche
  Forschungsgemeinschaft (DFG) under Project-ID 496854903 (SA4064/2-1, PI Sander)
  VR, GGT, and AACS further acknowledge support from the Federal Ministry of Education
  and Research (BMBF) and the Baden-Württemberg Ministry of Science as part of the
  Excellence Strategy of the German Federal and State Governments. ECS acknowledges
  financial support by the Federal Ministry for Economic Affairs and Climate Action
  (BMWK) via the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt,
  DLR) grant 50 OR 2306 (PI: Ramachandran/Sander). This work has received funding
  from the European Research Council (ERC) under the European Union’s Horizon 2020
  research and innovation programme (Grant agreement No. 945806) and is supported
  by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s
  Excellence Strategy EXC 2181/1-390900948 (the Heidelberg STRUCTURES Excellence Cluster).
  LMO is thankful for the funding provided by the DFG grant 443790621. This paper
  benefited from discussions at the International Space Science Institute (ISSI) in
  Bern through ISSI International Team project 512 (Multiwavelength View on Massive
  Stars in the Era of Multimessenger Astronomy). DP acknowledges financial support
  by the Deutsches Zentrum für Luft und Raumfahrt (DLR) grant FKZ 50OR2005. JIV acknowledges
  the European Research Council for support from the ERC Advanced grant ERC-2021-ADG101054731.
  JSV is supported by STFC (Science and Technology Facilities Council) funding under
  grant number ST/V000233/1. GH, SS-D, SRB and AH acknowledge support from the State
  Research Agency (AEI) of the Spanish Ministry of Science and Innovation (MICIN)
  and the European Regional Development Fund, FEDER under grants PID2021-122397NB-C21
  and CEX2019-000920-S. SRB also acknowledges financial support by NextGeneration
  EU/PRTR and MIU (UNI/551/2021) through grant Margarita Salas-ULL. DFR is thankful
  for the support of the CAPES-Br and FAPERJ/DSC-10 (SEI-260003/001630/2023). F.N.,
  and L.R.P. acknowledge support by grants PID2019-105552RB-C41 and PID2022-137779OB-C41
  funded by MCIN/AEI/10.13039/501100011033 by “ERDF A way of making Europe”. MG acknowledges
  financial support from the grants PID2021-125485NB-C22, CEX2019-000918-M funded
  by MCIN/AEI/10.13039/501100011033 (State Agency for Research of the Spanish Ministry
  of Science and Innovation) and SGR-2021-01069 (AGAUR). GM acknowledges funding support
  from the European Research Council (ERC) under the European Union’s Horizon 2020
  research and innovation programme (Grant agreement No. 772086). JMA acknowledges
  support from the Spanish Government Ministerio de Ciencia e Innovación and Agencia
  Estatal de Investigación (10.13 039/501 100 011 033) through grant PID2022-136640
  NB-C22 and from the Consejo Superior de Investigaciones Científicas (CSIC) through
  grant 2022-AEP 005. MP is supported by the BEKKER fellowship BPN/BEK/2022/1/00106
  from the Polish National Agency for Academic Exchange. KS is funded by the National
  Science Center (NCN), Poland, under grant number OPUS 2021/41/B/ST9/00757. JM acknowledges
  support from a Royal Society-Science Foundation Ireland University Research Fellowship.
  SJ acknowledges support from the FWO PhD fellowship under project 11E1721N. FB acknowledges
  the support of the European Research Council (ERC) Horizon Europe under grant agreement
  number 101044048.'
article_number: A289
article_processing_charge: Yes (in subscription journal)
article_type: original
arxiv: 1
author:
- first_name: T.
  full_name: Shenar, T.
  last_name: Shenar
- first_name: J.
  full_name: Bodensteiner, J.
  last_name: Bodensteiner
- first_name: H.
  full_name: Sana, H.
  last_name: Sana
- first_name: P. A.
  full_name: Crowther, P. A.
  last_name: Crowther
- first_name: D. J.
  full_name: Lennon, D. J.
  last_name: Lennon
- first_name: M.
  full_name: Abdul-Masih, M.
  last_name: Abdul-Masih
- first_name: L. A.
  full_name: Almeida, L. A.
  last_name: Almeida
- first_name: F.
  full_name: Backs, F.
  last_name: Backs
- first_name: S. R.
  full_name: Berlanas, S. R.
  last_name: Berlanas
- first_name: M.
  full_name: Bernini-Peron, M.
  last_name: Bernini-Peron
- first_name: J. M.
  full_name: Bestenlehner, J. M.
  last_name: Bestenlehner
- first_name: D. M.
  full_name: Bowman, D. M.
  last_name: Bowman
- first_name: V. A.
  full_name: Bronner, V. A.
  last_name: Bronner
- first_name: N.
  full_name: Britavskiy, N.
  last_name: Britavskiy
- first_name: A.
  full_name: De Koter, A.
  last_name: De Koter
- first_name: S. E.
  full_name: De Mink, S. E.
  last_name: De Mink
- first_name: K.
  full_name: Deshmukh, K.
  last_name: Deshmukh
- first_name: C. J.
  full_name: Evans, C. J.
  last_name: Evans
- first_name: M.
  full_name: Fabry, M.
  last_name: Fabry
- first_name: M.
  full_name: Gieles, M.
  last_name: Gieles
- first_name: A.
  full_name: Gilkis, A.
  last_name: Gilkis
- first_name: G.
  full_name: González-Torà, G.
  last_name: González-Torà
- first_name: G.
  full_name: Gräfener, G.
  last_name: Gräfener
- first_name: Ylva Louise Linsdotter
  full_name: Götberg, Ylva Louise Linsdotter
  id: d0648d0c-0f64-11ee-a2e0-dd0faa2e4f7d
  last_name: Götberg
  orcid: 0000-0002-6960-6911
- first_name: C.
  full_name: Hawcroft, C.
  last_name: Hawcroft
- first_name: V.
  full_name: Hénault-Brunet, V.
  last_name: Hénault-Brunet
- first_name: A.
  full_name: Herrero, A.
  last_name: Herrero
- first_name: G.
  full_name: Holgado, G.
  last_name: Holgado
- first_name: S.
  full_name: Janssens, S.
  last_name: Janssens
- first_name: C.
  full_name: Johnston, C.
  last_name: Johnston
- first_name: J.
  full_name: Josiek, J.
  last_name: Josiek
- first_name: S.
  full_name: Justham, S.
  last_name: Justham
- first_name: V. M.
  full_name: Kalari, V. M.
  last_name: Kalari
- first_name: Z. Z.
  full_name: Katabi, Z. Z.
  last_name: Katabi
- first_name: Z.
  full_name: Keszthelyi, Z.
  last_name: Keszthelyi
- first_name: J.
  full_name: Klencki, J.
  last_name: Klencki
- first_name: J.
  full_name: Kubát, J.
  last_name: Kubát
- first_name: B.
  full_name: Kubátová, B.
  last_name: Kubátová
- first_name: N.
  full_name: Langer, N.
  last_name: Langer
- first_name: R. R.
  full_name: Lefever, R. R.
  last_name: Lefever
- first_name: B.
  full_name: Ludwig, B.
  last_name: Ludwig
- first_name: J.
  full_name: Mackey, J.
  last_name: Mackey
- first_name: L.
  full_name: Mahy, L.
  last_name: Mahy
- first_name: J.
  full_name: Maíz Apellániz, J.
  last_name: Maíz Apellániz
- first_name: I.
  full_name: Mandel, I.
  last_name: Mandel
- first_name: G.
  full_name: Maravelias, G.
  last_name: Maravelias
- first_name: P.
  full_name: Marchant, P.
  last_name: Marchant
- first_name: A.
  full_name: Menon, A.
  last_name: Menon
- first_name: F.
  full_name: Najarro, F.
  last_name: Najarro
- first_name: L. M.
  full_name: Oskinova, L. M.
  last_name: Oskinova
- first_name: A. J.G.
  full_name: O'Grady, A. J.G.
  last_name: O'Grady
- first_name: R.
  full_name: Ovadia, R.
  last_name: Ovadia
- first_name: L. R.
  full_name: Patrick, L. R.
  last_name: Patrick
- first_name: D.
  full_name: Pauli, D.
  last_name: Pauli
- first_name: M.
  full_name: Pawlak, M.
  last_name: Pawlak
- first_name: V.
  full_name: Ramachandran, V.
  last_name: Ramachandran
- first_name: M.
  full_name: Renzo, M.
  last_name: Renzo
- first_name: D. F.
  full_name: Rocha, D. F.
  last_name: Rocha
- first_name: A. A.C.
  full_name: Sander, A. A.C.
  last_name: Sander
- first_name: T.
  full_name: Sayada, T.
  last_name: Sayada
- first_name: F. R.N.
  full_name: Schneider, F. R.N.
  last_name: Schneider
- first_name: A.
  full_name: Schootemeijer, A.
  last_name: Schootemeijer
- first_name: E. C.
  full_name: Schösser, E. C.
  last_name: Schösser
- first_name: C.
  full_name: Schürmann, C.
  last_name: Schürmann
- first_name: K.
  full_name: Sen, K.
  last_name: Sen
- first_name: S.
  full_name: Shahaf, S.
  last_name: Shahaf
- first_name: S.
  full_name: Simón-Díaz, S.
  last_name: Simón-Díaz
- first_name: M.
  full_name: Stoop, M.
  last_name: Stoop
- first_name: S.
  full_name: Toonen, S.
  last_name: Toonen
- first_name: F.
  full_name: Tramper, F.
  last_name: Tramper
- first_name: J. Th
  full_name: Van Loon, J. Th
  last_name: Van Loon
- first_name: R.
  full_name: Valli, R.
  last_name: Valli
- first_name: L. A.C.
  full_name: Van Son, L. A.C.
  last_name: Van Son
- first_name: A.
  full_name: Vigna-Gómez, A.
  last_name: Vigna-Gómez
- first_name: J. I.
  full_name: Villaseñor, J. I.
  last_name: Villaseñor
- first_name: J. S.
  full_name: Vink, J. S.
  last_name: Vink
- first_name: C.
  full_name: Wang, C.
  last_name: Wang
- first_name: R.
  full_name: Willcox, R.
  last_name: Willcox
citation:
  ama: 'Shenar T, Bodensteiner J, Sana H, et al. Binarity at LOw Metallicity (BLOeM):
    A spectroscopic VLT monitoring survey of massive stars in the SMC. <i>Astronomy
    &#38; Astrophysics</i>. 2024;690. doi:<a href="https://doi.org/10.1051/0004-6361/202451586">10.1051/0004-6361/202451586</a>'
  apa: 'Shenar, T., Bodensteiner, J., Sana, H., Crowther, P. A., Lennon, D. J., Abdul-Masih,
    M., … Willcox, R. (2024). Binarity at LOw Metallicity (BLOeM): A spectroscopic
    VLT monitoring survey of massive stars in the SMC. <i>Astronomy &#38; Astrophysics</i>.
    EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202451586">https://doi.org/10.1051/0004-6361/202451586</a>'
  chicago: 'Shenar, T., J. Bodensteiner, H. Sana, P. A. Crowther, D. J. Lennon, M.
    Abdul-Masih, L. A. Almeida, et al. “Binarity at LOw Metallicity (BLOeM): A Spectroscopic
    VLT Monitoring Survey of Massive Stars in the SMC.” <i>Astronomy &#38; Astrophysics</i>.
    EDP Sciences, 2024. <a href="https://doi.org/10.1051/0004-6361/202451586">https://doi.org/10.1051/0004-6361/202451586</a>.'
  ieee: 'T. Shenar <i>et al.</i>, “Binarity at LOw Metallicity (BLOeM): A spectroscopic
    VLT monitoring survey of massive stars in the SMC,” <i>Astronomy &#38; Astrophysics</i>,
    vol. 690. EDP Sciences, 2024.'
  ista: 'Shenar T, Bodensteiner J, Sana H, Crowther PA, Lennon DJ, Abdul-Masih M,
    Almeida LA, Backs F, Berlanas SR, Bernini-Peron M, Bestenlehner JM, Bowman DM,
    Bronner VA, Britavskiy N, De Koter A, De Mink SE, Deshmukh K, Evans CJ, Fabry
    M, Gieles M, Gilkis A, González-Torà G, Gräfener G, Götberg YLL, Hawcroft C, Hénault-Brunet
    V, Herrero A, Holgado G, Janssens S, Johnston C, Josiek J, Justham S, Kalari VM,
    Katabi ZZ, Keszthelyi Z, Klencki J, Kubát J, Kubátová B, Langer N, Lefever RR,
    Ludwig B, Mackey J, Mahy L, Maíz Apellániz J, Mandel I, Maravelias G, Marchant
    P, Menon A, Najarro F, Oskinova LM, O’Grady AJG, Ovadia R, Patrick LR, Pauli D,
    Pawlak M, Ramachandran V, Renzo M, Rocha DF, Sander AAC, Sayada T, Schneider FRN,
    Schootemeijer A, Schösser EC, Schürmann C, Sen K, Shahaf S, Simón-Díaz S, Stoop
    M, Toonen S, Tramper F, Van Loon JT, Valli R, Van Son LAC, Vigna-Gómez A, Villaseñor
    JI, Vink JS, Wang C, Willcox R. 2024. Binarity at LOw Metallicity (BLOeM): A spectroscopic
    VLT monitoring survey of massive stars in the SMC. Astronomy &#38; Astrophysics.
    690, A289.'
  mla: 'Shenar, T., et al. “Binarity at LOw Metallicity (BLOeM): A Spectroscopic VLT
    Monitoring Survey of Massive Stars in the SMC.” <i>Astronomy &#38; Astrophysics</i>,
    vol. 690, A289, EDP Sciences, 2024, doi:<a href="https://doi.org/10.1051/0004-6361/202451586">10.1051/0004-6361/202451586</a>.'
  short: T. Shenar, J. Bodensteiner, H. Sana, P.A. Crowther, D.J. Lennon, M. Abdul-Masih,
    L.A. Almeida, F. Backs, S.R. Berlanas, M. Bernini-Peron, J.M. Bestenlehner, D.M.
    Bowman, V.A. Bronner, N. Britavskiy, A. De Koter, S.E. De Mink, K. Deshmukh, C.J.
    Evans, M. Fabry, M. Gieles, A. Gilkis, G. González-Torà, G. Gräfener, Y.L.L. Götberg,
    C. Hawcroft, V. Hénault-Brunet, A. Herrero, G. Holgado, S. Janssens, C. Johnston,
    J. Josiek, S. Justham, V.M. Kalari, Z.Z. Katabi, Z. Keszthelyi, J. Klencki, J.
    Kubát, B. Kubátová, N. Langer, R.R. Lefever, B. Ludwig, J. Mackey, L. Mahy, J.
    Maíz Apellániz, I. Mandel, G. Maravelias, P. Marchant, A. Menon, F. Najarro, L.M.
    Oskinova, A.J.G. O’Grady, R. Ovadia, L.R. Patrick, D. Pauli, M. Pawlak, V. Ramachandran,
    M. Renzo, D.F. Rocha, A.A.C. Sander, T. Sayada, F.R.N. Schneider, A. Schootemeijer,
    E.C. Schösser, C. Schürmann, K. Sen, S. Shahaf, S. Simón-Díaz, M. Stoop, S. Toonen,
    F. Tramper, J.T. Van Loon, R. Valli, L.A.C. Van Son, A. Vigna-Gómez, J.I. Villaseñor,
    J.S. Vink, C. Wang, R. Willcox, Astronomy &#38; Astrophysics 690 (2024).
das_tickbox: '1'
date_created: 2024-11-03T23:01:44Z
date_published: 2024-10-01T00:00:00Z
date_updated: 2026-07-08T06:44:06Z
day: '01'
ddc:
- '520'
department:
- _id: YlGo
doi: 10.1051/0004-6361/202451586
external_id:
  arxiv:
  - '2407.14593'
  isi:
  - '001336770600014'
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  date_created: 2024-11-04T09:52:26Z
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file_date_updated: 2024-11-04T09:52:26Z
fulldoi: https://doi.org/10.1051/0004-6361/202451586
has_accepted_license: '1'
intvolume: '       690'
isi: 1
language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
publication: Astronomy & Astrophysics
publication_identifier:
  eissn:
  - 1432-0746
  issn:
  - 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey
  of massive stars in the SMC'
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 690
year: '2024'
...