Multiplicity of Galactic Luminous Blue Variable stars

Abstract

Context. Luminous Blue Variables (LBVs) are thought to be in a transitory phase between O stars on the main-sequence and the Wolf-Rayet stage. Recent studies suggest that they might be formed through binary interaction. Only a few are known in binary systems but their multiplicity fraction is uncertain. Aims. This study aims at deriving the binary fraction among the Galactic (confirmed and candidate) LBV population. We combine multi-epoch spectroscopy and long-baseline interferometry. Methods. We use cross-correlation to measure their radial velocities. We identify spectroscopic binaries through significant RV variability (larger than 35 km/s). We investigate the observational biases to establish the intrinsic binary fraction. We use CANDID to detect interferometric companions, derive their parameters and positions. Results. We derive an observed spectroscopic binary fraction of 26 %. Considering period and mass ratio ranges from Porb=1 to 1000 days, and q = 0.1-1.0, and a representative set of orbital parameter distributions, we find a bias-corrected binary fraction of 62%. From interferometry, we detect 14 companions out of 18 objects, providing a binary fraction of 78% at projected separations between 1 and 120 mas. From the derived primary diameters, and the distances of these objects, we measure for the first time the exact radii of Galactic LBVs to be between 100 and 650 Rsun, making unlikely to have short-period systems. Conclusions. This analysis shows that the binary fraction among the Galactic LBV population is large. If they form through single-star evolution, their orbit must be initially large. If they form through binary channel that implies 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 or that LBVs form through merging in initially binary or triple systems.

14 pages, 9 figures, 4 tables; Accepted for publication in A&A. (Abstract shortened to respect the arXiv limit of 1920 characters)

References in corpus (56)

• Binary interaction dominates the evolution of massive stars
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Mass-loss predictions for O and B stars as a function of metallicity
• Mind your Ps and Qs: the Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars
• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection
• The VLT-FLAMES Tarantula Survey VIII. Multiplicity properties of the O-type star population
• HERMES: a high-resolution fibre-fed spectrograph for the Mercator telescope
• The incidence of stellar mergers and mass gainers among massive stars
• PIONIER: a 4-telescope visitor instrument at VLTI
• Quantitative Spectroscopy of O Stars at Low Metallicity. O Dwarfs in NGC 346
• Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor stars
• On the progenitor of SN 2005gl and the nature of Type IIn supernovae
• Luminous Blue Variables are Antisocial: Their Isolation Implies that they are Kicked Mass Gainers in Binary Evolution
• Stellar envelope inflation near the Eddington limit. Implications for the radii of Wolf-Rayet stars and luminous blue variables
• The VLT-FLAMES Tarantula Survey XXII. Multiplicity properties of the B-type stars
• Cross-Correlation and Maximum Likelihood Analysis: A New Approach to Combine Cross-Correlation Functions
• Massive main sequence stars evolving at the Eddington limit
• Luminous Blue Variables and superluminous supernovae from binary mergers
• The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars II. A grid of O-type stars in the Galaxy and the Magellanic Clouds
• On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle
• Massive star evolution: Luminous Blue Variables as unexpected Supernova progenitors
• Why binary interaction does not necessarily dominate the formation of Wolf-Rayet stars at low metallicity
• Is HR 6819 a triple system containing a black hole? -- An alternative explanation
• Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
• MN48: a new Galactic bona fide luminous blue variable revealed by Spitzer and SALT
• On the Social Traits of Luminous Blue Variables
• Light-echoes from the plateau in Eta Carinae's Great Eruption reveal a two-stage shock-powered event
• Bona-fide, strong-variable galactic Luminous Blue Variable stars are fast rotators: detection of a high rotational velocity in HR Carinae
• The Tarantula Massive Binary Monitoring: III. Atmosphere analysis of double-lined spectroscopic systems
• Was the nineteenth century giant eruption of Eta Carinae a merger event in a triple system?
• The young massive SMC cluster NGC 330 seen by MUSE II. Multiplicity properties of the massive-star population
• Spectroscopic monitoring of the luminous blue variable Westerlund1-243 from 2002 to 2009
• The first X-ray survey of Galactic Luminous Blue Variables
• Wind-envelope interaction as the origin of the slow cyclic brightness variations of luminous blue variables
• On the Gaia DR2 distances for Galactic Luminous Blue Variables
• The B-type Binaries Characterisation Programme I. Orbital solutions for the 30 Doradus population
• Modelling Luminous-Blue-Variable Isolation
• A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors
• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars. I. The northern WC sequence
• Shedding Light on the Isolation of Luminous Blue Variables
• The Age of Westerlund 1 Revisited
• An explanation for the curious mass loss history of massive stars: from OB stars, through Luminous Blue Variables to Wolf-Rayet stars
• The isolation of Luminous Blue Variables: On subdividing the sample
• On the nature of high reddening of Cygnus OB2 #12 hypergiant
• A Binary Orbit for the Massive, Evolved Star HDE 326823, a WR+O System Progenitor
• A new investigation of the binary HD 48099
• Modelling the asymmetric wind of the luminous blue variable binary MWC 314
• A modern study of HD166734: a massive supergiant system
• Inferring the parallax of Westerlund 1 from Gaia DR2
• The isolation of Luminous Blue Variables resembles aging B-type supergiants, not the most massive unevolved stars
• Luminous blue variables: An imaging perspective on their binarity and near environment
• Tracing back the evolution of the candidate LBV HD168625
• Variations on a theme -- the puzzling behaviour of Schulte 12
• Confirmation of the Luminous Blue Variable status of MWC 930

Cited by in corpus (20)

• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars: II. The northern WNE sequence
• The statistical properties of early-type stars from LAMOST DR8
• A spectroscopic multiplicity survey of Galactic Wolf-Rayet stars. III. The northern late-type nitrogen-rich sample
• A VLT/FLAMES survey for massive binaries in Westerlund 1: VIII. Binary Systems and Orbital Parameters
• Binarity at Low Metallicity (BLOeM) -- Multiplicity properties of Oe and Be stars
• Investigating 39 Galactic Wolf-Rayet stars with VLTI/GRAVITY: Uncovering A Long Period Binary Desert
• The multiplicity of massive stars in the Scorpius OB1 association through high-contrast imaging
• Are magnetic fields universal in O-type multiple systems?
• Binarity at LOw Metallicity (BLOeM): Multiplicity of early B-type supergiants in the Small Magellanic Cloud
• Search for LBVs in the Local Volume galaxies: study of two stars in NGC 1156
• Luminous Blue Variables
• Kinematics of Luminous Blue Variables in the Large Magellanic Cloud
• The binary fraction of Blue Horizontal-Branch (BHB) Stars
• LBV phenomenon and binarity: The environment of HR Car
• On variability of DDO68-V1, a unique extremely metal-poor LBV
• Hot Stars in the GALEX Ultraviolet Sky Surveys (GUVcat_AISxSDSS_HS) and the Binary Fraction of Hot Evolved Stars
• Large-scale variability in macroturbulence driven by pulsations in the rapidly rotating massive star Zeta Oph from high-cadence ESPRESSO spectroscopy and TESS photometry
• A Low Metallicity Massive Contact Binary Star System Candidate in WLM identified by Hubble and James Webb Space Telescope imaging
• The symphony of pulsations and binarity among massive stars using HERMES spectroscopy and TESS photometry
• Accretion in massive colliding wind binaries and the effect of wind momentum ratio