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Title: Modelling the asymmetric wind of the luminous blue variable binary MWC 314
Authors: Lobel, A. ×
Groh, J. H.
Martayan, C.
Frémat, Y.
Torres Dozinel, K.
Raskin, Gert
Van Winckel, Hans
Prins, Saskia
Pessemier, Wim
Waelkens, Christoffel
Hensberge, H.
Dummortier, L.
Jorissen, A.
Van Eck, S.
Lehmann, H. #
Issue Date: Nov-2013
Publisher: EDP Sciences
Series Title: Astronomy & Astrophysics vol:559 pages:28
Article number: A16
Abstract: Aims: We present a spectroscopic analysis of MWC 314, a luminous blue variable (LBV) candidate with an extended bipolar nebula. The detailed spectroscopic variability is investigated to determine if MWC 314 is a massive binary system with a supersonically accelerating wind or a low-mass B[e] star. We compare the spectrum and spectral energy distribution to other LBVs (such as P Cyg) and find very similar physical wind properties, indicating strong kinship.
Methods: We combined long-term high-resolution optical spectroscopic monitoring and V-band photometric observations to determine the orbital elements and stellar parameters and to investigate the spectral variability with the orbital phases. We developed an advanced model of the large-scale wind-velocity and wind-density structure with 3-D radiative transfer calculations that fit the orbitally modulated P Cyg profile of He i λ5876, showing outflow velocities above 1000 km s-1.
Results: We find that MWC 314 is a massive semi-detached binary system of ≃1.22 AU, observed at an inclination angle of i = 72.8° with an orbital period of 60.8 d and e = 0.23. The primary star is a low-vsini LBV candidate of m1 = 39.6 M⊙ and R1 = 86.8 R⊙. The detailed radiative transfer fits show that the geometry of wind density is asymmetric around the primary star with increased wind density by a factor of 3.3, which leads the orbit of the primary. The variable orientation causes the orbital modulation that is observed in absorption portions of P Cyg wind lines. Wind accretion in the system produces a circumbinary disc.
Conclusions: MWC 314 is in a crucial evolutionary phase of close binary systems, when the massive primary star has its H envelope being stripped and is losing mass to a circumbinary disc. MWC 314 is a key system for studying the evolutionary consequences of these effects.

Table 1, Figs. 1-4, 9, 10, 14-16, 18-20, 23 are available in electronic form at http://www.aanda.org
ISSN: 0004-6361
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
Physics and Astronomy - miscellaneous
× corresponding author
# (joint) last author

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