The VLT-FLAMES Tarantula Survey V. The peculiar B[e]-like supergiant, VFTS698, in 30 Doradus

Dunstall, P. R.; Fraser, M.; Clark, J. S.; Crowther, P. A.; Dufton, P. L.; Evans, C. J.; Lennon, D. J.; Soszynski, I.; Taylor, W. D. and Vink, J. S. (2012). The VLT-FLAMES Tarantula Survey V. The peculiar B[e]-like supergiant, VFTS698, in 30 Doradus. Astronomy & Astrophysics, 542, article no. A50.

DOI: https://doi.org/10.1051/0004-6361/201218872

Abstract

Aims. We present an analysis of a peculiar supergiant B-type star (VFTS698/Melnick 2/Parker 1797) in the 30 Doradus region of the Large Magellanic Cloud which exhibits characteristics similar to the broad class of B[e] stars.

Methods. We analyse optical spectra from the VLT-FLAMES survey, together with archival optical and infrared photometry and X-ray imaging to characterise the system.

Results. We find radial velocity variations of around 400 kms⁻¹ in the high excitation Si iv, Niii and He ii spectra, and photometric variability of ~0.6mag with a period of 12.7 d. In addition, we detect long-term photometric variations of ~0.25mag, which may be due to a longer-term variability with a period of ~400 d.

Conclusions. We conclude that VFTS698 is likely an interacting binary comprising an early B-type star secondary orbiting a veiled, more massive companion. Spectral evidence suggests a mid-to-late B-type primary, but this may originate from an optically-thick accretion disc directly surrounding the primary.

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