J/A+A/698/A38 BLOeM. Oe and Be stars (Bodensteiner+, 2025)
Binarity at LOw Metallicity (BLOeM). Multiplicity properties of Oe and Be stars.
Bodensteiner J., Shenar T., Sana H., Britavskiy N., Crowther P.A.,
Langer N., Lennon D.J., Mahy L., Patrick L.R., Villasenor J.I.,
Abdul-Masih M., Bowman D.M., de Koter A., de Mink S.E., Deshmukh K.,
Fabry M., Gilkis A., Goetberg Y., Holgado G., Izzard R.G., Janssens S.,
Kalari V.M., Keszthelyi Z., Kubat J., Mandel I., Maravelias G.,
Oskinova L.M., Pauli D., Ramachandran V., Rocha D.F., Renzo M.,
Sander A.A.C., Schneider F.R.N., Schootemeijer A., Sen K., Stoop M.,
Toonen S., van Loon J.T., Valli R., Vigna-Gomez A., Vink J.S., Wang C.,
Xu X.-T.
<Astron. Astrophys. 698, A38 (2025)>
=2025A&A...698A..38B 2025A&A...698A..38B (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Stars, O ; Stars, emission ; Stars, Be ;
MK spectral classification
Keywords: binaries: close - binaries: spectroscopic - stars: emission-line -
stars: massive - Magellanic Clouds
Abstract:
Rapidly rotating classical OBe stars have been proposed as the products
of binary interactions, and the fraction of Be stars with compact
companions implies that at least some are. However, to constrain the
interaction physics spinning up the OBe stars, a large sample of
homogeneously analysed OBe stars with well-determined binary
characteristics and orbital parameters are required. We investigate
the multiplicity properties of a sample of 18 Oe, 62 Be, and two Of?p
stars observed within the BLOeM survey in the Small Magellanic Cloud.
We analyse the first nine epochs of spectroscopic observations
obtained over approximately three months in 2023. Radial velocities
(RVs) of all stars are measured. Applying commonly-used binarity
criteria we classify objects as binaries, binary candidates, and
apparently single (RV stable) objects. We further inspect the spectra
for double-lined spectroscopic binaries and cross-match with
catalogues of X-ray sources and photometric binaries. We classify 14
OBe stars as binaries, and an additional 11 as binary candidates. The
two Of?p stars are apparently single. Two more objects are most likely
currently interacting binaries. Without those, the observed binary
fraction for the OBe sample (78 stars) is fOBeobs=0.18±0.04
(fobscand=0.32±0.05 including candidates). This fraction is less
than half of that measured for OB stars in BLOeM. Combined with the
lower fraction of SB2s, this suggests that OBe stars have indeed
fundamentally different binary properties than OB stars. We find no
evidence for OBe binaries with massive compact companions, in contrast
to expectations from binary population synthesis. Our results support
the binary scenario as an important formation channel for OBe stars,
as post-interaction binaries may have been disrupted or the stripped
companions of OBe stars are harder to detect.
Description:
In this study, we investigate the binary properties of 82 OBe stars
observed in the context of the BLOeM survey. We measured RVs using the
CCF technique in nine epochs obtained over the course of almost three
months with the FLAMES multi-object spectrograph at the VLT, and
searched for RV variations. Both the stellar absorption lines and the
emission lines characteristic of these types of objects are
investigated. All spectra were visually inspected for signatures of
SB2s.
Tables C1 and C2 summarize the parameters of all binaries and
candidates (C1) and RV-stable stars (C2).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablec1.dat 117 27 Parameters of all binaries and candidates
tablec2.dat 102 55 Parameters of RV-stable stars
--------------------------------------------------------------------------------
See also:
J/A+A/690/A289 : Binarity at LOw Metallicity (BLOeM). I. (Shenar+, 2024)
J/A+A/698/A39 : BLOeM. BAF-type supergiants (Patrick+, 2025)
J/A+A/698/A40 : BLOeM. SMC early B supergiants multiplicity (Britavskiy+ 2025)
J/A+A/698/A41 : BLOeM. Early B dwarfs and giants at Z=0.2 (Villasenor+, 2025)
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- BLOeM BLOeM identifier, BLOeM N-NNN
13- 31 I19 --- GaiaDR3 Gaia DR3 identifier
33- 42 F10.7 deg RAdeg Right ascension (J2000)
44- 54 F11.7 deg DEdeg Declination (J2000)
56- 60 F5.2 mag Gmag Gaia G magnitude
62- 77 A16 --- SpType Spectral type
79- 83 F5.1 km/s DRVmax Maximum RV amplitude between two epochs
85- 88 F4.1 km/s e_DRVmax Maximum RV amplitude between two epochs error
90 A1 --- C1 [F/T] Binary ?
92 A1 --- C2 [F/T] RV-stable star ?
94- 97 A4 --- Status [bin/cand ] Status, binary or candidate
99-105 A7 --- Type Type of binary
107-117 A11 --- Lit Literature (G1)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- BLOeM BLOeM identifier, BLOeM N-NNN
13- 31 I19 --- GaiaDR3 Gaia DR3 identifier
33- 42 F10.7 deg RAdeg Right ascension (J2000)
44- 54 F11.7 deg DEdeg Declination (J2000)
56- 60 F5.2 mag Gmag Gaia G magnitude
62- 76 A15 --- SpType Spectral type from Paper I (Shenar et al.,
2024A&A...690A.289S 2024A&A...690A.289S, Cat. J/A+A/690/A289)
78- 81 F4.1 km/s DRVmax Maximum RV amplitude between two epochs
83- 86 F4.1 km/s e_DRVmax Maximum RV amplitude between two epochs error
88-102 A15 --- Lit Literature (G1)
--------------------------------------------------------------------------------
Global notes:
Note (G1): Classification based on OGLE-III photometry from Pawlak et al.
(2013AcA....63..323P 2013AcA....63..323P, Cat. J/AcA/63/323).
X-ray source identifications are from
1 = Evans et al. (2010ApJS..189...37E 2010ApJS..189...37E, Cat. IX/45, IX/57)
2 = Sturm et al. (2013A&A...558A...3S 2013A&A...558A...3S, Cat. J/A+A/558/A3
3 = Wang et al. (2016ApJS..224...40W 2016ApJS..224...40W, Cat. J/ApJS/224/40)
4 = Laycock et al. ( 2010ApJ...716.1217L 2010ApJ...716.1217L, Cat. J/ApJ/716/1217)
5 = Traulsen et al. (2020A&A...641A.137T 2020A&A...641A.137T, Cat. IX/61 IX/64 IX/66)
6 = Antoniou & Zezas (2016MNRAS.459..528A 2016MNRAS.459..528A)
--------------------------------------------------------------------------------
Acknowledgements:
Julia Bodensteiner, j.bodensteiner(at)uva.nl
References:
Shenar et al., Paper I 2024A&A...690A.289S 2024A&A...690A.289S, Cat. J/A+A/690/A289
(End) Patricia Vannier [CDS] 26-Feb-2025