Modelling the asymmetric wind of the luminous blue variable binary MWC 314

Lobel, A.; Groh, J. H.; Martayan, Christophe; Frémat, Y.; Dozinel, K. Torres; Raskin, Gert; Winckel, H. Van; Prins, S.; Pessemier, Wim; Waelkens, Christoffel; Hensberge, H.; Dummortier, L.; Jorissen, A.; Eck, S. Van; Lehmann, H.

doi:10.1051/0004-6361/201220421

Cited by 22 publications

(39 citation statements)

References 51 publications

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“…is also supported by the absence of circumstellar dust, analogously to P Cyg, as already noted by Miroshnichenko (1996) and confirmed by the spectral energy distributions of these two stars in Lobel et al (2013). This might mean that the dust has been blown away by the wind and one or more LBV outbursts, which occurred a long time ago.…”

Section: Introductionsupporting

confidence: 73%

Interpreting the spectral behavior of MWC 314

Frasca

Мирошниченко

Rossi

et al. 2015

A&A

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Context. MWC 314 is one of the most luminous stars in the Milky Way. Its fundamental parameters are similar to those of luminous blue variables (LBVs), although no large photometric variations have been recorded. Moreover, it shows no evidence of either a dust shell or a relevant spectral variability. Aims. The main purpose of this work is to clarify the origin of the radial velocity and line profile variations exhibited by absorption and emission lines. Methods. We analyzed the radial velocity (RV) variations displayed by the absorption lines from the star's atmosphere using highresolution optical spectra and fitting the RV curve with an eccentric orbit model. We also studied the RV and profile variations of some permitted and forbidden emission lines of metallic ions with a simple geometric model. The behavior of the Balmer and He i lines has also been investigated. Results. Fourier analysis applied to the RV of the absorption lines clearly shows a 60-day periodicity. A dense coverage of the RV curve allowed us to derive accurate orbital parameters. The RV of the Fe ii emission lines varies in the same way, but with a smaller amplitude. Additionally, the intensity ratio of the blue/red peaks of these emission lines correlates with the RV variations. The first three members of the Balmer series as well as [N ii] lines display a nearly constant RV and no profile variations in phase with the orbital motion instead. The He i λ5876 Å line shows a strongly variable profile with broad and blue-shifted absorption components that reach velocities of ≤−1000 km s −1 in some specific orbital phases. Conclusions. Our data and analysis provide strong evidence that the object is a binary system composed of a supergiant B[e] star and an undetected companion. The emission lines with a non-variable RV could originate in a circumbinary region. For the Fe ii emission lines, we propose a simple geometrical two-component model where a compact source of Fe ii emission, moving around the center of mass, is affected by a static extra absorption that originates from a larger area. Finally, the blue-shifted absorption in the He i λ5876 Å line could be the result of density enhancements in the primary star wind that is flowing towards the companion, and which is best observed when projected over the disk of the primary star.

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Section: Introductionsupporting

confidence: 73%

Interpreting the spectral behavior of MWC 314

Frasca

Мирошниченко

Rossi

et al. 2015

A&A

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“…Those authors showed that the emission lines of various atomic species spanning a wide range of ionizations states Lobel et al 2013), at arbitrary orbital phases, and RY Scuti (green dash-triple-dotted line; from Smith et al 2002). The velocities were shifted to center the entire profiles.…”

Section: Is Nast1 the Product Of Mass Transfer?mentioning

confidence: 99%

Multiwavelength observations of NaSt1 (WR 122): equatorial mass loss and X-rays from an interacting Wolf–Rayet binary

Mauerhan

Smith

Dyk

et al. 2015

Monthly Notices of the Royal Astronomical Society

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NaSt1 (aka Wolf-Rayet 122) is a peculiar emission-line star embedded in an extended nebula of [N ii] emission with a compact dusty core. This object was characterized by Crowther & Smith (1999) as a Wolf-Rayet (WR) star cloaked in an opaque nebula of CNO-processed material, perhaps analogous to η Car and its Homunculus nebula, albeit with a hotter central source. To discern the morphology of the [N ii] nebula we performed narrowband imaging using the Hubble Space Telescope and Wide-field Camera 3. The images reveal that the nebula has a disk-like geometry tilted ≈12 • from edge-on, composed of a bright central ellipsoid surrounded by a larger clumpy ring. Ground-based spectroscopy reveals radial velocity structure (±10 km s −1 ) near the outer portions of the nebula's major axis, which is likely to be the imprint of outflowing gas. Near-infrared adaptive-optics imaging with Magellan AO has resolved a compact ellipsoid of K s -band emission aligned with the larger [N ii] nebula, which we suspect is the result of scattered He i line emission (λ2.06 µm). Observations with the Chandra X-ray Observatory have revealed an X-ray point source at the core of the nebula that is heavily absorbed at energies < 1 keV and has properties consistent with WR stars and colliding-wind binaries. We suggest that NaSt1 is a WR binary embedded in an equatorial outflow that formed as the result of non-conservative mass transfer. NaSt1 thus appears to be a rare and important example of a stripped-envelope WR forming through binary interaction, caught in the brief Roche-lobe overflow phase.

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“…IRAS 17163 would need to have an orbital velocity of at least 50 km s −1 to explain the velocity discrepancy between the CO and Fe II lines. For example, the LBV binary MWC 314 has an orbital speed of ∼100 km s −1 (Lobel et al 2013). The binary hypothesis also requires that the companion be relatively optically faint as there is no indication of lines at a very different velocity in the optical spectrum.…”

Section: Velocity Discrepancymentioning

confidence: 99%

Investigating the nature of the Fried Egg nebula

Wallström

Müller

Lagadec

et al. 2015

A&A

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Through CO mm-line and optical spectroscopy, we investigate the properties of the Fried Egg nebula IRAS 17163-3907, which has recently been proposed to be one of the rare members of the yellow hypergiant class. The CO J = 2−1 and J = 3−2 emission arises from a region within 20 of the star and is clearly associated with the circumstellar material. The CO lines show a multi-component asymmetrical profile, and an unexpected velocity gradient is resolved in the east-west direction, suggesting a bipolar outflow. This is in contrast with the apparent symmetry of the dust envelope as observed in the infrared. The optical spectrum of IRAS 17163-3907 between 5100 and 9000 Å was compared with that of the archetypal yellow hypergiant IRC+10420 and was found to be very similar. These results build on previous evidence that IRAS 17163-3907 is a yellow hypergiant.

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Modelling the asymmetric wind of the luminous blue variable binary MWC 314

Cited by 22 publications

References 51 publications

Interpreting the spectral behavior of MWC 314

Interpreting the spectral behavior of MWC 314

Multiwavelength observations of NaSt1 (WR 122): equatorial mass loss and X-rays from an interacting Wolf–Rayet binary

Investigating the nature of the Fried Egg nebula

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