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| Paper: |
Modeling the Asymmetric Wind of Massive LBV Binary MWC 314 |
| Volume: |
465, Four Decades of Massive Star Research - A Scientific Meeting in Honor of Anthony J. Moffat |
| Page: |
358 |
| Authors: |
Lobel, A.; Groh, J.; Torres Dozinel, K.; Gorlova, N.; Martayan, C.; Raskin, G.; Van Winckel, H.; Prins, S.; Pessemier, W.; Waelkens, C.; Frémat, Y.; Hensberge, H.; Dummortier, L.; Jorissen, A.; Van Eck, S.; Lehmann, H. |
| Abstract: |
Spectroscopic monitoring with Mercator-HERMES over the past two years reveals
that MWC 314 is a massive binary system composed of an early B-type primary
LBV star and a less-luminous supergiant companion. We determine an orbital
period Porb of 60.85 d from optical S II and Ne I
absorption lines observed in this single-lined spectroscopic binary. We find an
orbital eccentricity of e = 0.26, and a large amplitude of the radial velocity
curve of 80.6 km s-1. The ASAS V light-curve during our spectroscopic
monitoring reveals two brightness minima (ΔV = 0.1 mag)
over the orbital period due to partial eclipses at an orbital inclination angle
of ∼ 70°. We find a clear correlation between the orbital phases and the detailed shapes
of optical and near-IR P Cygni-type line profiles of He I, Si II,
and double- or triple-peaked stationary cores of prominent Fe II emission
lines. A preliminary 3-D radiative transfer model computed with Wind3D
shows that the periodic P Cygni line profile variability results from an
asymmetric common-envelope wind with enhanced density (or line opacity) in the
vicinity of the LBV primary. The variable orientation of the inner LBV wind
region due to the orbital motion produces variable P Cygni line profiles (with
wind velocities of ∼ 200 km s-1) between orbital phases φ =
0.65 to 0.85, while weak inverse P Cygni profiles are observed half an orbital
period later around φ = 0.15 to 0.35. We do not observe optical or near-IR
He II, C III, and Si III lines, signaling that the LBV's
spectral type is later than B0. Detailed modeling of the asymmetrical wind
properties of massive binary MWC 314 provides important new physical information
about the most luminous hot (binary) stars such as η Carinae. |
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