P. R. Dunstall, M. Fraser, J. S. Clark, P. A. Crowther, P. L. Dufton, C. J. Evans, D. J. Lennon, I. Soszyński, W. D. Taylor, J. S. Vink
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. We analyse
optical spectra from the VLT-FLAMES survey, together with archival optical and
infrared photometry and X-ray imaging to characterise the system. We find
radial velocity variations of around 400 km/s 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 days. 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 days.
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.
View original:
http://arxiv.org/abs/1201.6389
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