Published September 2012
| Version v1
Journal article
The relationship between γ Cassiopeiae's X-ray emission and its circumstellar environment. II. Geometry and kinematics of the disk from MIRC and VEGA instruments on the CHARA Array
Creators
- Stee, Ph.
- Delaa, O.
- Monnier, J. D.
- Meilland, A.
- Perraut, K.
- Mourard, D.
- Che, X.
- Schaefer, G. H.
- Pedretti, E.
- Smith, M. A.
- Lopes de Oliveira, R.
- Motch, C.
- Henry, G. W.
- Richardson, N. D.
- Bjorkman, K. S.
- Bücke, R.
- Pollmann, E.
- Zorec, J.
- Gies, D. R.
- ten Brummelaar, T.
- Mcalister, H. A.
- Turner, N. H.
- Sturmann, J.
- Sturmann, L.
- Ridgway, S. T.
Contributors
Others:
- Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Department of Astronomy [Ann Arbor] ; University of Michigan [Ann Arbor] ; University of Michigan System-University of Michigan System
- Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ) ; Observatoire des Sciences de l'Univers de Grenoble (OSUG) ; Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Institut für Theoretische Physik [Heidelberg] ; Universität Heidelberg [Heidelberg]
- SUPA School of Physics and Astronomy [University of St Andrews] ; University of St Andrews [Scotland]-Scottish Universities Physics Alliance (SUPA)
- College of Natural Science and Mathematics [Houston] ; University of Houston
- Department of Chemistry and Biochemistry [Tucson] ; University of Arizona
- Universidade Federal de Sergipe, Departamento de Física ; Universidade Federal de Sergipe, Departamento de Física
- Observatoire astronomique de Strasbourg (ObAS) ; Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Center of Excellence in Information Systems ; Center of Excellence in Information Systems
- Center for High Angular Resolution Astronomy (CHARA) ; Georgia State University ; University System of Georgia (USG)-University System of Georgia (USG)
- Ritter Astrophysical Research Center ; University of Toledo
- Anna-von-Gierke-Ring ; Anna-von-Gierke-Ring
- Emil-Nolde-Str ; Emil-Nolde-Str
- Institut d'Astrophysique de Paris (IAP) ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
- National Optical Astronomy Observatory (NOAO)
Description
Context.γ Cas is thought to be the prototype of classical Be stars and is the most studied object among this group. However, as for all Be stars, the origin and the physics of its circumstellar disk responsible for the observed near IR-excess, emission lines, and peculiar X-ray emission is still being debated. Aims: We constrain the geometry and kinematics of its circumstellar disk from the highest spatial resolution ever achieved on this star. This investigation is a part of a large multi-technique observing campaign to obtain the most complete picture of γ Cas which emphasizes the relation of the circumstellar environment to the star's X-ray flux. Methods: We present new observations in the near infrared (MIRC) and in the visible (VEGA) obtained with the CHARA interferometer. The VEGA instrument allows us to not only obtain a global disk geometry but also spectrally dispersed visibility modulus and phases within the Hα emission line, which enables us to study the kinematics within γ Cas's disk. Results: We obtain a disk extension in the nearby Hα continuum of 1.72 stellar diameter and 1.86 stellar diameter in the H band at 1.65 μm assuming a Gaussian disk model but also compatible with an elliptical ring model with a minor internal diameter of 1.38 stellar diameter in H. For the first time we demonstrate that the rotation mapped by the emission in the Hα line within the disk of γ Cas and up to 10 R⋆ is Keplerian. Conclusions: These observations have pushed the size of the disk to greater proportions. γ Cas was also confirmed to be a nearly critical rotator. The disk imaging gives neither indication of a 1-arm spiral feature nor evidence of a secondary star reinforcing the interpretation that the secondary is certainly a low-mass and low-luminosity star or a degenerate companion.
Abstract
International audienceAdditional details
Identifiers
- URL
- https://hal.archives-ouvertes.fr/hal-00766118
- URN
- urn:oai:HAL:hal-00766118v1
Origin repository
- Origin repository
- UNICA