The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars

Abstract

We present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. We investigate the spatial distribution of the radial velocities across the 30 Dor region, and use the results to identify candidate runaway stars. Excluding potential runaways and members of two older clusters in the survey region (SL 639 and Hodge 301), we determine a systemic velocity for 30 Dor of 271.6 +/- 12.2 km/s from 273 presumed single stars. Employing a 3-sigma criterion we identify nine candidate runaway stars (2.9% of the single stars with radial-velocity estimates). The projected rotational velocities of the candidate runaways appear to be significantly different to those of the full B-type sample, with a strong preference for either large (>345 km/s) or small (<65 km/s) rotational velocities. Of the candidate runaways, VFTS 358 (classified B0.5: V) has the largest differential radial velocity (-106.9 +/- 16.2 km/s), and a preliminary atmospheric analysis finds a significantly enriched nitrogen abundance of 12+log(N/H) > ~8.5. Combined with a large rotational velocity (vsini = 345 +/- 22 km/s), this is suggestive of past binary interaction for this star.

39 pages (main body: 14 pages; ancillary material: 25 pages)

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• The VLT-FLAMES Tarantula Survey XIX. B-type Supergiants - Atmospheric parameters and nitrogen abundances to investigate the role of binarity and the width of the main sequence
• The ESO Diffuse Interstellar Bands Large Exploration Survey: EDIBLES I. Project description, survey sample and quality assessment
• The VLT-FLAMES Tarantula Survey. XXX. Red stragglers in the clusters Hodge 301 and SL 639
• Spectroscopic evolution of massive stars on the main sequence
• The VLT-FLAMES Tarantula Survey: XXXI. Radial velocities and multiplicity constraints of red supergiant stars in 30 Doradus
• The VMC Survey XXII. Hierarchical Star Formation in the 30 Doradus-N158-N159-N160 Star-Forming Complex
• Hubble Tarantula Treasury Project V. The star cluster Hodge 301: the old face of 30 Doradus
• Pillars of creation amongst destruction: Star formation in molecular clouds near R136 in 30 Doradus
• Effective temperature of ionizing stars of extragalactic HII regions
• HST/COS Spectra of the Wind Lines of VFTS 102 and 285