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

Autor(en)

Noel D. Richardson, Anthony F J Moffat, Raphael Maltais-Tariant, Herbert Pablo, Douglas R. Gies, Rainer Kuschnig, Werner Wolfgang Weiss

Abstrakt

MWC 314 is a bright candidate luminous blue variable 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\prime-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 synchronisation at periastron, we estimate the component masses to be M1 ≈ 5 M_⊙ and M2 ≈ 15 M_⊙, 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.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Université de Montréal, Georgia State University

Journal

Monthly Notices of the Royal Astronomical Society

Band

455

Seiten

244 - 257

Anzahl der Seiten

14

ISSN

0035-8711

DOI

https://doi.org/10.1093/mnras/stv2291

Publikationsdatum

2016

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie, 103004 Astrophysik

Schlagwörter

ASJC Scopus Sachgebiete

Astronomy and Astrophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/spectroscopy-most-photometry-and-interferometry-of-mwc-314-is-it-an-lbv-or-an-interacting-binary(636668eb-8541-4b2e-929e-934594340797).html