VEGA: Visible spEctroGraph and polArimeter for the CHARA array: principle and performance
Denis Mourard,Jean-Michel Clausse,A. Marcotto,Karine Perraut,I. Tallon-Bosc,Ph. Berio,A. Blazit,D. Bonneau,S. Bosio,Yves Bresson,Olivier Chesneau,O. Delaa,François Hénault,Y. Hughes,Stephane Lagarde,G. Merlin,A. Roussel,Alain Spang,Ph. Stee,M. Tallon,P. Antonelli,R. Foy,Pierre Kervella,Romain Petrov,Éric Thiébaut,Farrokh Vakili,Harold A. McAlister,T. ten Brummelaar,J. Sturmann,Laszlo Sturmann,Nils H. Turner,Chris Farrington,P. J. Goldfinger +32 more
TLDR
The spectro-polarimeter VEGA has been installed and successfully tested on the CHARA Array as mentioned in this paper, and the results depend on the observing conditions (seeing, spectral resolution, etc.).Abstract:
Context. Among optical stellar interferometers, the CHARA Array located at Mt Wilson in California offers the potential of very long baselines (up to 330 m) and the prospect of coupling multiple beam combiners. This paper presents the principle and the measured performance of VEGA, Visible spEctroGraph and polArimeter installed in September 2007 at the coherent focus of the array.Aims. With 0.3 ms of arc of spatial resolution and up to of spectral resolution, VEGA intends to measure fundamental parameters of stars, to study stellar activities and to image and analyze circumstellar environments. We describe the observing modes that have been implemented for this spectro-polarimeter and show actual performances measured on the sky during the first observing runs.Methods. The astrophysical programs are described in relation to the observing modes of the instrument, the presentation of the spectrograph and of the interface table is shown and finally the data is presented. We discuss the perspectives of further development in the framework of the CHARA Array.Results. We show that VEGA/CHARA is fully operational. The current limiting magnitude is nearly 7 but the results depend on the observing conditions (seeing, spectral resolution, etc.). We have validated the stability of the instrumental visibility at the level of 1 to 2% over half an hour and of the instrumental polarization for various declinations. Some examples of squared visibility and differential visibility are presented.Conclusions. The spectro-polarimeter VEGA has been installed and successfully tested on CHARA. It will permit stellar physics studies at unprecedented spectral and spatial resolutions.read more
Citations
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Radiative hydrodynamic simulations of red supergiant stars - III. Spectro-photocentric variability, photometric variability, and consequences on Gaia measurements
Andrea Chiavassa,Ester Pasquato,Alain Jorissen,Stéphane Sacuto,Carine Babusiaux,Bernd Freytag,Bernd Freytag,Hans-Günter Ludwig,Pierre Cruzalèbes,Yves Rabbia,A. Spang,Olivier Chesneau +11 more
TL;DR: In this paper, the impact of convection on the photocentric and photometric variability of red supergiant stars has been explored, and it has been shown that the effect of the convective granulation on the photocentre of a red supergiants could have adverse effects on the parallax determination with Gaia.
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First spectro-interferometric survey of Be stars I. Observations and constraints on the disk geometry and kinematics
Anthony Meilland,Florentin Millour,S. Kanaan,Philippe Stee,Romain Petrov,Karl-Heinz Hofmann,Antonella Natta,Karine Perraut +7 more
TL;DR: In this paper, a survey on the circumstellar environment of the brightest Be stars was conducted using spectro-interferometry, which showed that rotation is dominant by rotation with a rotation law close to the Keplerian one.
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Spectral and spatial imaging of the Be+sdO binary ϕ Persei
Denis Mourard,John D. Monnier,A. Meilland,D. R. Gies,Florentin Millour,Myriam Benisty,Myriam Benisty,Xiao Che,Erika D. Grundstrom,R. Ligi,Gail Schaefer,Fabien Baron,Fabien Baron,Stefan Kraus,Ming Zhao,Ettore Pedretti,Philippe Berio,J. M. Clausse,N. Nardetto,Karine Perraut,Karine Perraut,A. Spang,P. Stee,I. Tallon-Bosc,H. A. McAlister,T. ten Brummelaar,S. T. Ridgway,J. Sturmann,L. Sturmann,Neal J. Turner,Chris Farrington +30 more
TL;DR: In this paper, the first high-resolution images of ϕ Persei made possible by new capabilities in long-baseline interferometry at near-IR and visible wavelengths were presented.
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The relationship between γ Cassiopeiae’s X-ray emission and its circumstellar environment
Myron A. Smith,R. Lopes de Oliveira,R. Lopes de Oliveira,Christian Motch,Gregory W. Henry,Noel D. Richardson,Karen S. Bjorkman,Ph. Stee,D. Mourard,John D. Monnier,Xiao Che,R. Bücke,E. Pollmann,D. R. Gies,Gail Schaefer,T. ten Brummelaar,Harold A. McAlister,Nils H. Turner,Judit Sturmann,L. Sturmann,S. T. Ridgway +20 more
TL;DR: In this article, the authors measured radial velocities from the Hα line and redetermined its period as 203.55 ± 0.20 days and its eccentricity as near zero.
Journal ArticleDOI
First spectro-interferometric survey of Be stars I. Observations and constraints on the disks geometry and kinematics
Anthony Meilland,Florentin Millour,S. Kanaan,Philippe Stee,Romain Petrov,Karl-Heinz Hofmann,Antonella Natta,Karine Perraut +7 more
TL;DR: In this article, a survey on the circumstellar environment of the brightest Be stars was conducted using spectro-interferometry, which showed that rotation is the main physical process driving the mass-ejection.
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First Results from the CHARA Array. II. A Description of the Instrument
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