The VLT-FLAMES Tarantula Survey

V. The peculiar B[e]-like supergiant, VFTS698, in 30 Doradus^⋆,⋆⋆

¹ Department of Physics & AstronomyThe Queen’s University of Belfast, BT7 1NN, Northern Ireland, UK
e-mail: pdunstall01@qub.ac.uk
² Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
³ Department of Physics & Astronomy, University of Sheffield, Sheffield S3 7RH, UK
⁴ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK
⁵ ESA, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁶ Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
⁷ Institute for Astronomy, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, UK
⁸ Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK

Received: 23 January 2012
Accepted: 4 April 2012

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 km s^-1 in the high excitation Si iv, N iii and He ii spectra, and photometric variability of  ~0.6 mag with a period of 12.7 d. In addition, we detect long-term photometric variations of  ~0.25 mag, 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.