Schnorringen Telescope Science Institute

Waldbröl, Germany

Schnorringen Telescope Science Institute

Waldbröl, Germany
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Fahed R.,University of Montréal | Moffat A.F.J.,University of Montréal | Zorec J.,University Pierre and Marie Curie | Eversberg T.,Schnorringen Telescope Science Institute | And 18 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2011

We present the results from the spectroscopic monitoring of WR 140 (WC7pd + O5.5fc) during its latest periastron passage in 2009 January. The observational campaign consisted of a constructive collaboration between amateur and professional astronomers. It took place at six locations, including Teide Observatory, Observatoire de Haute Provence, Dominion Astrophysical Observatory and Observatoire du Mont Mégantic. WR 140 is known as the archetype of colliding-wind binaries and it has a relatively long period (8 yr) and high eccentricity (0.9). 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 and colliding-wind geometry. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.


Fahed R.,University of Montréal | Moffat A.F.J.,University of Montréal | Zorec J.,CNRS Paris Institute of Astrophysics | Eversberg T.,Schnorringen Telescope Science Institute | Chene A.N.,Herzberg Institute for Astrophysics
Stellar Winds in Interaction - Proceedings of the International ProAm Workshop on Stellar Winds | Year: 2010

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.


Pablo H.,University of Montréal | Richardson N.D.,University of Montréal | Moffat A.F.J.,University of Montréal | Corcoran M.,NASA | And 47 more authors.
Astrophysical Journal | Year: 2015

We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system δ Ori A, consisting of a binary O9.5II+early-B (Aa1 and Aa2) with P = 5.7 days, and a more distant tertiary (O9 IV years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV) curve of Aa1. While we are unable to recover RV variations of the secondary star, we are able to constrain several fundamental parameters of this system and determine an approximate mass of the primary using apsidal motion. We also detected second order modulations at 12 separate frequencies with spacings indicative of tidally influenced oscillations. These spacings have never been seen in a massive binary, making this system one of only a handful of such binaries that show evidence for tidally induced pulsations. © 2015. The American Astronomical Society. All rights reserved..


Fahed R.,University of Montréal | Moffat A.F.J.,University of Montréal | Zorec J.,CNRS Paris Institute of Astrophysics | Eversberg T.,Schnorringen Telescope Science Institute | And 27 more authors.
Proceedings of the International Astronomical Union | Year: 2010

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. © International Astronomical Union 2011.


Miroshnichenko A.S.,University of North Carolina at Greensboro | Pasechnik A.V.,University of Turku | Manset N.,CFHT Corporation | Carciofi A.C.,University of Sao Paulo | And 19 more authors.
Astrophysical Journal | Year: 2013

We describe the results of the world-wide observing campaign of the highly eccentric Be binary system δ Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092 ± 0.0005 yr. Fitting of the He II 4686 Å line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9-day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 M⊙) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the Hα line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 R⊙. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that δ Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40° with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations. © 2013. The American Astronomical Society. All rights reserved.


Aldoretta E.J.,University of Montréal | St-Louis N.,University of Montréal | Richardson N.D.,University of Toledo | Moffat A.F.J.,University of Montréal | And 59 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2016

During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He II λ5411 emission line, the previously identified period was refined to P = 2.255 ± 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 ± 6 d, or ~18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Δφ ≃ 90° was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C IV λλ5802,5812 and He I λ5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He I λ5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist. © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Rauw G.,University of Liège | Morel T.,University of Liège | Naze Y.,University of Liège | Eversberg T.,Schnorringen Telescope Science Institute | And 28 more authors.
Astronomy and Astrophysics | Year: 2015

Context. The two Oe stars HD 45 314 and HD 60 848 have recently been found to exhibit very different X-ray properties: whilst HD 60 848 has an X-ray spectrum and the emission level typical of most OB stars, HD 45 314 features a much harder and brighter X-ray emission, making it a so-called γ Cas analogue. Aims. Monitoring the optical spectra could provide hints towards the origin of these very different behaviours. Methods. We analyse a large set of spectroscopic observations of HD 45 314 and HD 60 848, extending over 20 years. We further attempt to fit the Hα line profiles of both stars with a simple model of emission line formation in a Keplerian disk. Results. Strong variations in the strengths of the Hα, Hβ, and He Ι λ 5876 emission lines are observed for both stars. In the case of HD 60 848, we find a time lag between the variations in the equivalent widths of these lines, which is currently not understood. The emission lines are double peaked with nearly identical strengths of the violet and red peaks. The Hα profile of this star can be successfully reproduced by our model of a disk seen under an inclination of 30°. In the case of HD 45 314, the emission lines are highly asymmetric and display strong line profile variations. We find a major change in behaviour between the 2002 outburst and the one observed in 2013. This concerns both the relationship between the equivalent widths of the various lines and their morphologies at maximum strength (double-peaked in 2002 versus single-peaked in 2013). Our simple disk model fails to reproduce the observed Hα line profiles of HD 45 314. Conclusions. Our results further support the interpretation that Oe stars do have decretion disks similar to those of Be stars. Whilst the emission lines of HD 60 848 are explained well by a disk with a Keplerian velocity field, the disk of HD 45 314 seems to have a significantly more complex velocity field that could be another signature of the phenomenon that produces its peculiar X-ray emission. © ESO, 2015.

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