Spectroscopy, MOST photometry, and interferometry of MWC 314: Is it an LBV or an interacting binary?

Noel D. Richardson, Anthony F.J. Moffat, Raphäel Maltais-Tariant, Herbert Pablo, Douglas R. Gies, Hideyuki Saio, Nicole St-Louis, Gail Schaefer, Anatoly S. Miroshnichenko, Chris Farrington, Emily J. Aldoretta, Étienne Artigau, Tabetha S. Boyajian, Kathryn Gordon, Jeremy Jones, Rachel Matson, Harold A. McAlister, David O'Brien, Deepak Raghavan, Tahina Ramiaramanantsoa & 17 others Stephen T. Ridgway, Nic Scott, Judit Sturmann, Laszlo Sturmann, Theo Ten Brummelaar, Joshua D. Thomas, Nils Turner, Norm Vargas, Sergey Zharikov, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner W. Weiss

Research output: Contribution to journalArticleResearchpeer-review

Abstract

MWC 314 is a bright candidate luminous blue variable (LBV) that resides in a fairly close binary system, with an orbital period of 60.753 ± 0.003 d. We observed MWC 314 with a combination of optical spectroscopy, broad-band ground- and space-based photometry, as well as with long baseline, near-infrared interferometry. We have revised the single-lined spectroscopic orbit and explored the photometric variability. The orbital light curve displays two minima each orbit that can be partially explained in terms of the tidal distortion of the primary that occurs around the time of periastron. The emission lines in the system are often double-peaked and stationary in their kinematics, indicative of a circumbinary disc. We find that the stellar wind or circumbinary disc is partially resolved in the K'-band with the longest baselines of the CHARA Array. From this analysis, we provide a simple, qualitative model in an attempt to explain the observations. From the assumption of Roche Lobe overflow and tidal synchronization at periastron, we estimate the component masses to be M1 ≈ 5M and M2 ≈15M, which indicates a mass of the LBV that is extremely low. In addition to the orbital modulation, we discovered two pulsational modes with the MOST satellite. These modes are easily supported by a low-mass hydrogen-poor star, but cannot be easily supported by a star with the parameters of an LBV. The combination of these results provides evidence that the primary star was likely never a normal LBV, but rather is the product of binary interactions. As such, this system presents opportunities for studying mass-transfer and binary evolution with many observational techniques.

Original languageEnglish
Pages (from-to)244-257
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume455
Issue number1
DOIs
Publication statusPublished - 1 Jan 2016
Externally publishedYes

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Keywords

  • Binaries: close-Stars: early-type-Stars
  • Individual
  • Massloss-Stars
  • MWC 314-Stars
  • S Doradus-Stars
  • Variables
  • winds-Outflows

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Richardson, N. D., Moffat, A. F. J., Maltais-Tariant, R., Pablo, H., Gies, D. R., Saio, H., ... Weiss, W. W. (2016). Spectroscopy, MOST photometry, and interferometry of MWC 314: Is it an LBV or an interacting binary? Monthly Notices of the Royal Astronomical Society, 455(1), 244-257. https://doi.org/10.1093/mnras/stv2291