The VLT-FLAMES Tarantula Survey: XXXI. Radial velocities and multiplicity constraints of red supergiant stars in 30 Doradus

Abstract

The incidence of multiplicity in cool, luminous massive stars is relatively unknown compared to their hotter counterparts. Here we present radial velocity (RV) measurements and investigate the multiplicity properties of red supergiants (RSGs) in the 30~Doradus region of the Large Magellanic Cloud. We provide absolute RV measurements for our sample and estimate line-of-sight velocities for the Hodge 301 and SL 639 clusters, which agree well with those of hot stars in the same clusters. By combining results for the RSGs with those for nearby B-type stars, we estimate systemic velocities and velocity dispersions for the two clusters, obtaining estimates for their dynamical masses of $\log (M_{\mathrm{dyn}}/M_{\odot })=$3.8$\pm$0.3 for Hodge 301, and an upper limit of $\log (M_{\mathrm{dyn}}/M_{\odot })$<3.1$\pm$0.8 for SL 639, assuming Virial equilibrium. Analysis of the multi-epoch data reveals one RV-variable, potential binary candidate (VFTS744), which is likely a semi-regular variable asymptotic giant branch star. We estimate an upper limit on the observed binary fraction for our sample of 0.3, where we are sensitive to maximum periods for individual objects in the range of 1 to 10 000 days and mass-ratios above 0.3 depending on the data quality. From simulations of the RV measurements from binary systems given the current data we conclude that systems within the parameter range q>0.3, $\log$P[days]<3.5, would be detected by our variability criteria, at the 90% confidence level. The intrinsic binary fraction, accounting for observational biases, is estimated using simulations of binary systems with an empirically defined distribution of parameters where orbital periods are uniformly distributed in the 3.3<$\log$P[days]<4.3 range. A range of intrinsic binary fractions are considered; a binary fraction of 0.3 is found to best reproduce the observed data. [Abridged]

accepted in A&A

References in corpus (19)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Binary interaction dominates the evolution of massive stars
• Southern Massive Stars at High Angular Resolution: Observational Campaign and Companion Detection
• The High Angular Resolution Multiplicity of Massive Stars
• The effect of massive binaries on stellar populations and supernova progenitors
• Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey
• Variability in red supergiant stars: pulsations, long secondary periods and convection noise
• The impact of companions on stellar evolution
• The Tarantula Massive Binary Monitoring: I. Observational campaign and OB-type spectroscopic binaries
• Atmospheric dynamics and the mass loss process in red supergiant stars
• Fundamental properties and atmospheric structure of the red supergiant VY CMa based on VLTI/AMBER spectro-interferometry
• The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars
• What causes the large extensions of red-supergiant atmospheres? Comparisons of interferometric observations with 1-D hydrostatic, 3-D convection, and 1-D pulsating model atmospheres
• A new survey of cool supergiants in the Magellanic Clouds
• The VLT-FLAMES Tarantula Survey. XXX. Red stragglers in the clusters Hodge 301 and SL 639
• A dearth of short-period massive binaries in the young massive star forming region M17: Evidence for a large orbital separation at birth?
• Hubble Tarantula Treasury Project V. The star cluster Hodge 301: the old face of 30 Doradus
• Multi-epoch VLTI-PIONIER imaging of the supergiant V766 Cen: Image of the close companion in front of the primary
• Mass segregation in young star clusters: can it be detected from the integrated photometric properties?

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• Multiplicity of the red supergiant population in the young massive cluster NGC 330
• Properties of the Be-type stars in 30 Doradus
• Red supergiant stars in binary systems. I. Identification and characterisation in the Small Magellanic Cloud from the UVIT ultraviolet imaging survey