J/A+A/698/A39 BLOeM. BAF-type supergiants (Patrick+, 2025)
Binarity at LOw Metallicity (BLOeM).
The multiplicity properties and evolution of BAF-type supergiants.
Patrick L.R., Lennon D.J., Najarro F., Shenar T., Bodensteiner J., Sana H.,
Crowther P.A., Britavskiy N., Langer N., Schootemeijer A., Evans C.J.,
Mahy L., Goetberg Y., de Mink S.E., Schneider F.R.N., O'Grady A.J.G.,
Villasenor J.I., Bernini-Peron M., Bowman D.M., de Koter A., Deshmukh K.,
Gilkis A., Gonzalez-Tora G., Kalari V.M., Keszthelyi Z., Mandel I.,
Menon A., Moe M., Oskinova L.M., Pauli D., Renzo M., Sander A.C., Sen K.,
Stoop M., van Loon J.T., Toonen S., Tramper F., Vink J.S., Wang C.
<Astron. Astrophys. 698, A39 (2025)>
=2025A&A...698A..39P 2025A&A...698A..39P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, supergiant ; Radial velocities
Keywords: binaries: general - binaries: spectroscopic - stars: massive -
supergiants - Magellanic Clouds
Abstract:
Given the uncertain evolutionary status of blue supergiant stars,
their multiplicity properties hold vital clues to better understand
their origin and evolution. As part of The Binarity at LOw Metallicity
(BLOeM) campaign in the Small Magellanic Cloud, we present a
multi-epoch spectroscopic survey of 128 supergiant stars of spectral
type B5-F5, which roughly correspond to initial masses in the
6-30M☉ range. The observed binary fraction for the B5-9
supergiants is 25±6% (10±4%) and 5±2% (0%) for the A-F stars,
which were found using a radial-velocity (RV) variability threshold of
5km/s (10km/s) as a criterion for binarity. Accounting for
observational biases, we find an intrinsic multiplicity fraction of
less than 18% for the B5-9 stars and 8+9-7% for the AF stars, for
the orbital periods up to 103.5days and mass ratios (q) in the
0.1<q<1 range. The large stellar radii of these supergiant stars
prevent short orbital periods, but we demonstrate that this effect
alone cannot explain our results. We assessed the spectra and RV time
series of the detected binary systems and find that only a small
fraction display convincing solutions. We conclude that the
multiplicity fractions are compromised by intrinsic stellar
variability, such that the true multiplicity fraction may be
significantly smaller. Our main conclusions from comparing the
multiplicity properties of the B5-9- and AF-type supergiants to that
of their less evolved counterparts is that such stars cannot be
explained by a direct evolution from the main sequence. Furthermore,
by comparing their multiplicity properties to red supergiant stars, we
conclude that the AF supergiant stars are neither progenitors nor
descendants of red supergiants.
Description:
In this work, we investigated the intrinsic RV variability and
multiplicity properties of the supergiant stars ranging from spectral
types B5 to F5 in the SMC.
Table B1: Velocity corrections (in km/s) for each field and epoch that
have to be added to the measured RVs.
Table B2: Measured radial velocities (km/s) and uncertainties for each
epoch.
Table B3: Mean radial velocities, their standard deviation (σ),
median value, and peak-to-peak velocity (p2p). Also listed is the
median of individual errors, the number of epochs available, and the
number of pairs of measurements satisfying Eq. (1). The effective
temperature and logarithmic luminosity are those derived here and used
in construction of the HRD. Candidate spectroscopic binaries are
flagged as "var" according to Fig.5 and `LP' marks the potential
long period system that does not meet the binary threshold. Candidate
alpha Cyg variables are also indicated.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 55 8 Velocity corrections for each field and epoch
that have to be added to the measured Vcs
tableb2.dat 29 1140 Measured radial velocities and uncertainties
for each epoch
tableb3.dat 78 129 Mean radial velocities, their standard deviation,
median value, and peak-to-peak velocity
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See also:
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/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: tableb1.dat
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Bytes Format Units Label Explanations
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1 I1 --- Field [1/8] Field number
3- 7 F5.2 km/s Vc1 Velocity correction at Epoch1
9- 13 F5.2 km/s Vc2 Velocity correction at Epoch2
15- 19 F5.2 km/s Vc3 Velocity correction at Epoch3
21- 25 F5.2 km/s Vc4 Velocity correction at Epoch4
27- 31 F5.2 km/s Vc5 Velocity correction at Epoch5
33- 37 F5.2 km/s Vc6 Velocity correction at Epoch6
39- 43 F5.2 km/s Vc7 Velocity correction at Epoch7
45- 49 F5.2 km/s Vc8 Velocity correction at Epoch8
51- 55 F5.2 km/s Vc9 Velocity correction at Epoch9
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- BLOeM BLOeM name (N-NNN)
7- 15 F9.3 d MJD Modified Julian date of observation
17- 23 F7.3 km/s RV Radial velocity
25- 29 F5.3 km/s e_RV Radial velocity error
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Byte-by-byte Description of file: tableb3.dat
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Bytes Format Units Label Explanations
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3- 7 A5 --- BLOeM BLOeM name (N-NNN)
9- 17 A9 --- SpType Spectral type
19- 24 F6.2 km/s RVmean Mean radial velocity
26- 29 F4.2 km/s sigma Standard deviation median value of
radial velocity
31- 36 F6.2 km/s RVmedian Median radial velocity
38- 42 F5.2 km/s p2p Peak-to-peak velocity)
44- 47 F4.2 km/s e_RVmedian Median radial velocity error
49 I1 --- Nepochs [3/9] Number of epochs available
51- 52 I2 --- n4 Number of pairs of measurements satisfying
Eq. (1) of the paper
54- 58 I5 K Teff Effective temperature (1)
60- 63 F4.2 [Lsun] logL Logarithmic luminosity (1)
65- 78 A14 --- Com Comment (2)
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Note (1): The effective temperature and logarithmic luminosity are those derived
here and used in construction of the HRD.
Note (2): Candidate spectroscopic binaries are flagged as "var" according to
Fig.5 and "LP" marks the potential long period system that does not meet the
binary threshold. Candidate alpha Cyg variables are also indicated as
"alpha Cyg var".
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Acknowledgements:
Lee Patrick, lrpatrick(at)cab.inta-csic.es
References:
Shenar et al., Paper I, 2024A&A...690A.289S 2024A&A...690A.289S, Cat. J/A+A/690/A289
(End) Patricia Vannier [CDS] 15-May-2025