Abstract
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.
Original language | English |
---|---|
Article number | A289 |
Journal | Astronomy and Astrophysics |
Volume | 690 |
DOIs | |
State | Published - 1 Oct 2024 |
Funding
Funders | Funder number |
---|---|
NextGeneration EU | |
Ministerio de Ciencia e Innovación | |
PRTR | |
Narodowa Agencja Wymiany Akademickiej | |
State Research Agency | |
Bundesministerium für Bildung und Forschung | |
Bundesministerium für Wirtschaft und Klimaschutz | |
Spanish Government Ministerio de Ciencia e Innovación | |
MICIN | |
Baden-Württemberg Ministry of Science | |
Royal Society-Science Foundation Ireland | |
International Space Science Institute | |
European Research Council | |
Horizon 2020 | |
UK Research and Innovation | |
Consejo Superior de Investigaciones Científicas | 2022-AEP 005, BPN/BEK/2022/1/00106 |
ERC Horizon Europe funding guarantee | EP/Y031059/1 |
Horizon 2020 Framework Programme | 772225 |
Agència de Gestió d'Ajuts Universitaris i de Recerca | 772086 |
HORIZON EUROPE Framework Programme | 101044048 |
Narodowe Centrum Nauki | OPUS 2021/41/B/ST9/00757 |
Agencia Estatal de Investigación | PID2022-136640 NB-C22, 10.13 039/501 100 011 033 |
Al-Mustafa International University | UNI/551/2021, PID2022-137779OB-C41, PID2019-105552RB-C41 |
Deutsche Forschungsgemeinschaft | 445674056, SA4064/1-1, Project-ID 496854903, SA4064/2-1 |
Deutsches Zentrum für Luft- und Raumfahrt | EXC 2181/1-390900948, FKZ 50OR2005, ST/V000233/1, 50 OR 2306, 945806, ERC-2021-ADG101054731, 443790621 |
Science and Technology Facilities Council | ST/V000853/1 |
European Regional Development Fund | CEX2019-000918-M, PID2021-125485NB-C22, SGR-2021-01069 |
Australian Research Council | CE230100016 |
Fonds Wetenschappelijk Onderzoek | 11E1721N |
Japan Society for the Promotion of Science | 23K19071 |
Royal Society | URF\R1\231631 |
CAPES-Br | SEI-260003/001630/2023, FAPERJ/DSC-10 |
Keywords
- Binaries: general
- Binaries: spectroscopic
- Magellanic Clouds
- Stars: massive