2022A&A...657A...4M


Query : 2022A&A...657A...4M

2022A&A...657A...4M - Astronomy and Astrophysics, volume 657A, 4-4 (2022/1-1)

Multiplicity of Galactic luminous blue variable stars.

MAHY L., LANTHERMANN C., HUTSEMEKERS D., KLUSKA J., LOBEL A., MANICK R., MISZALSKI B., REGGIANI M., SANA H. and GOSSET E.

Abstract (from CDS):

Context. Luminous blue variables (LBVs) are characterised by strong photometric and spectroscopic variability. They are thought to be in a transitory phase between O-type stars on the main sequence and the Wolf-Rayet stage. Recent studies also evoked the possibility that they might be formed through binary interaction. Only a few are known in binary systems so far, but their multiplicity fraction is still uncertain. Aims. We derive the binary fraction of the Galactic LBV population. We combine multi-epoch spectroscopy and long-baseline interferometry to probe separations from 0.1 to 120 mas around confirmed and candidate LBVs. Methods. We used a cross-correlation technique to measure the radial velocities of these objects. We identified spectroscopic binaries through significant radial velocity variability with an amplitude larger than 35 km/s. We also investigated the observational biases to take them into account when we established the intrinsic binary fraction. We usedCANDID to detect interferometric companions, derive their flux fractions, and their positions on the sky. Results. From the multi-epoch spectroscopy, we derive an observed spectroscopic binary fraction of 26–10+16%. Considering period and mass ratio ranges from log(Porb)=0-3 (i.e. from 1 to 1000 days), q = 0.1 - 1.0, and a representative set of orbital parameter distributions, we find a bias-corrected binary fraction of 62–24+38 %. Based on data of the interferometric campaign, we detect a binary fraction of 70 ±9% at projected separations between 1 and 120 mas. Based on the derived primary diameters and considering the distances of these objects, we measure for the first time the exact radii of Galactic LBVs to be between 100 and 650 R. This means that it is unlikely that short-period systems are included among LBV-like stars. Conclusions. This analysis shows for the first time that the binary fraction in the Galactic LBV population is large. If they form through single-star evolution, their orbit must be large initially. If they form through a binary channel, the implication is that either massive stars in short binary systems must undergo a phase of fully non-conservative mass transfer to be able to sufficiently widen the orbit to form an LBV, or that LBVs form through merging in initially binary or triple systems. Interferometric follow-up would provide the distributions of orbital parameters at more advanced stages and would serve to quantitatively test the binary evolution in massive stars.

Abstract Copyright: © ESO 2021

Journal keyword(s): stars: variables: S Doradus - stars: evolution - binaries: general - stars: massive

VizieR on-line data: <Available at CDS (J/A+A/657/A4): stars.dat tablea1.dat>

Simbad objects: 33

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Number of rows : 33
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10530 1
2 HD 5980 WR* 00 59 26.5838833944 -72 09 53.927337312   11.13 11.31   11.029 WN4+O7I: 380 1
3 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6555 1
4 HD 269128 s*b 05 10 22.7893360416 -68 46 23.816621928 9.77 10.52 10.412 10.29 10.268 B2.5Ieq 100 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16507 1
6 NAME 30 Dor Region reg 05 38.0 -69 06           ~ 217 0
7 HD 80077 s*b 09 15 54.7869062472 -49 58 24.575734452 10.50 10.29 9.00 7.89   B2Ia+e 136 0
8 HD 90177 s*b 10 22 53.8430096928 -59 37 28.363616256 9.16 9.66 8 8.15   LBV 321 0
9 * eta Car Em* 10 45 03.5377808928 -59 41 04.051599720 6.37 7.03 6.48 4.90 4.41 OBepec 2363 0
10 WRAY 15-682 WR* 10 53 59.5777329720 -60 26 44.361095316   11.64 10.85 10.56   WN11h 145 3
11 V* AG Car WR* 10 56 11.5781414448 -60 27 12.810673260 7.00 7.57 6.96 7.73   WN11h 617 0
12 MR 35 s*b 11 08 40.0634208096 -60 42 51.721320060   12.33 10.20 11.66   LBV 124 0
13 NAME Sher 25 star * 11 15 07.6447245696 -61 15 17.611428348   13.63 12.27     B1.5Iab 78 1
14 WRAY 16-232 Be* 16 43 16.3701582960 -46 00 42.406912656   17.12 12.5 12.92 10.25 Be 27 0
15 Cl* Westerlund 1 W 243 s*b 16 47 07.5040736160 -45 52 29.123491188   19.873 15.730     LBV 57 0
16 [GKF2010] MN48 LP* 16 49 37.7028749880 -45 35 59.233622064   17.64 15.83 13.82 10.82 ~ 11 0
17 * zet01 Sco s*b 16 53 59.7271314888 -42 21 43.307334468 4.80 5.31 4.79 4.32 3.86 B1Ia-0ek 362 0
18 HD 326823 WR* 17 06 53.9045282184 -42 36 39.704037840 9.68 9.87 9.03 9.51   WNpec 77 1
19 [B61] 2 s*b 17 41 35.4358256400 -30 06 38.782127520   18.0 15.00 14.23 10.30 LBV_B[e]: 44 0
20 HD 160529 sg* 17 41 59.0261939376 -33 30 13.704456780 8.17 7.87 6.66 5.50 4.51 A2Ia 192 1
21 [RHI84] 10-469 * 17 43 59.8045876752 -30 28 38.454065184     13.75     Be 7 0
22 NAME Pistol HII 17 46 15.2 -28 49 49           ~ 68 0
23 [FMM95] 3 s*b 17 46 15.240 -28 50 03.58           LBV 147 1
24 HD 316285 s*b 17 48 14.0372119152 -28 00 53.121269592 11.88 11.27 9.60 9.28   B0Ieq 187 2
25 HD 168607 s*b 18 21 14.8856951904 -16 22 31.763755236 10.23 9.82 8.28 8.55   B9Iaep 183 1
26 HD 168625 s*b 18 21 19.5484021368 -16 22 26.075142156 10.15 9.78 8.37 8.76   B6Iap 270 2
27 EM* MWC 930 s*b 18 26 25.2364693368 -07 13 17.815243512   14.20 11.51 11.87 9.40 B5/9Iaeq 45 1
28 BD-13 5061 sg* 18 39 26.1022628664 -13 50 47.159703852 10.86 10.75 9.89 9.98   B9Ia 38 1
29 MSX6C G026.4700+00.0207 s*b 18 39 32.2472383848 -05 44 20.185351872           LBV_B 40 1
30 BD+14 3887 Em* 19 21 33.9771479376 +14 52 56.910478296 11.86 11.3 9.89     B3Ibe 90 0
31 * P Cyg s*b 20 17 47.2020844 +38 01 58.552724 4.66 5.24 4.82 4.28 4.02 B1-2Ia-0ep 1160 1
32 Schulte 12 s*b 20 32 40.9572199728 +41 14 29.279036940 16.1 14.45 11.702     B3-4Ia+ 402 0
33 * rho Cas LP* 23 54 23.0325302520 +57 29 57.774737400 7.00 5.85 4.59 3.63 2.89 G2_0 378 0

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2023.01.27-19:20:20

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