References of "Eversberg, Thomas"
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See detailVariability monitoring of OB stars during the Mons campaign
Morel, Thierry ULg; Rauw, Grégor ULg; Eversberg, Thomas et al

in Neiner, Coralie; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)

We present preliminary results of a 4-month campaign carried out in the framework of the Mons project, where time-resolved Hα observations are used to study the wind and circumstellar properties of a ... [more ▼]

We present preliminary results of a 4-month campaign carried out in the framework of the Mons project, where time-resolved Hα observations are used to study the wind and circumstellar properties of a number of OB stars. [less ▲]

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See detailSpectroscopic follow-up of the colliding-wind binary WR 140 during the 2009 January periastron passage
Fahed, Rémi; Moffat, Anthony F J; Zorec, Juan et al

in Neiner, Coralie; Wade, G.; Meynet, G. (Eds.) et al Active OB stars: structure, evolution, mass loss and critical limits (2011, July 01)

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in january 2009. This object is known as the archetype of colliding wind binaries and has a ... [more ▼]

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in january 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (~=8 years) and eccentricity (~=0.89). We provide updated values for the orbital parameters, new estimates for the WR and O star masses and new constraints on the mass-loss rates. [less ▲]

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See detailCoordinated monitoring of the eccentric O-star binary Iota Orionis: optical spectroscopy and photometry
Marchenko, Sergey V; Rauw, Grégor ULg; Antokhina, Eleonora A et al

in Monthly Notices of the Royal Astronomical Society (2000), 317

With the objective of investigating the wind-wind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the ... [more ▼]

With the objective of investigating the wind-wind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9III+B1III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50°<~i<~70°. [less ▲]

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See detailA 2.3 Day Periodic Variability in the Apparently Single Wolf-Rayet Star WR 134: Collapsed Companion or Rotational Modulation?
Morel, Thierry ULg; Marchenko, Sergey V; Eenens, Philippe R J et al

in Astrophysical Journal (1999), 518

The apparently single WN 6 type star WR 134 (HD 191765) is distinguished among the Wolf-Rayet star population by its strong, presumably cyclical (P~2.3 day) spectral variations. A true periodicity-which ... [more ▼]

The apparently single WN 6 type star WR 134 (HD 191765) is distinguished among the Wolf-Rayet star population by its strong, presumably cyclical (P~2.3 day) spectral variations. A true periodicity-which is still very much debated-would render WR 134 a prime candidate for harboring either a collapsed companion or a rotating, large-scale, inhomogeneous outflow. We have carried out an intensive campaign of spectroscopic and photometric monitoring of WR 134 from 1989 to 1997 in an attempt to reveal the true nature of this object. This unprecedentedly large data set allows us to confirm unambiguously the existence of a coherent 2.25+/-0.05 day periodicity in the line-profile changes of He II lambda4686, although the global pattern of variability is different from one epoch to another. This period is only marginally detected in the photometric data set. Assuming the 2.25 day periodic variability to be induced by orbital motion of a collapsed companion, we develop a simple model that aims to investigate (1) the effect of this strongly ionizing, accreting companion on the Wolf-Rayet wind structure, and (2) the expected emergent X-ray luminosity. We argue that the predicted and observed X-ray fluxes can only be matched if the accretion on the collapsed star is significantly inhibited. Additionally, we performed simulations of line-profile variations caused by the orbital revolution of a localized, strongly ionized wind cavity surrounding the X-ray source. A reasonable fit is achieved between the observed and modeled phase-dependent line profiles of He II lambda4686. However, the derived size of the photoionized zone substantially exceeds our expectations, given the observed low-level X-ray flux. Alternatively, we explore rotational modulation of a persistent, largely anisotropic outflow as the origin of the observed cyclical variability. Although qualitative, this hypothesis leads to greater consistency with the observations. [less ▲]

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