Astronomy & Astrophysics

A&A 464, 73-79 (2007)
DOI: 10.1051/0004-6361:20065410

An asymmetry detected in the disk of $\kappa$ Canis Majoris with AMBER/VLTI

A. Meilland¹, F. Millour^{2, 3}, P. Stee¹, A. Domiciano de Souza^{2, 1}, R.G. Petrov², D. Mourard¹, S. Jankov², S. Robbe-Dubois², A. Spang¹, E. Aristidi², P. Antonelli¹, U. Beckmann⁴, Y. Bresson¹, A. Chelli³, M. Dugué¹, G. Duvert³, S. Gennari⁵, L. Glück³, P. Kern³, S. Lagarde¹, E. Le Coarer³, F. Lisi⁵, F. Malbet³, K. Perraut³, P. Puget³, F. Rantakyrö⁶, A. Roussel¹, E. Tatulli^{3, 5}, G. Weigelt⁴, G. Zins³, M. Accardo⁵, B. Acke^{3, 7}, K. Agabi², E. Altariba³, B. Arezki³, C. Baffa⁵, J. Behrend⁴, T. Blöcker⁴, S. Bonhomme¹, S. Busoni⁵, F. Cassaing⁸, J.-M. Clausse¹, J. Colin¹, C. Connot⁴, A. Delboulbé³, T. Driebe⁴, P. Feautrier³, D. Ferruzzi⁵, T. Forveille³, E. Fossat², R. Foy⁹, D. Fraix-Burnet³, A. Gallardo³, E. Giani⁵, C. Gil^{3, 10}, A. Glentzlin¹, M. Heiden⁴, M. Heininger⁴, O. Hernandez Utrera³, K.-H. Hofmann⁴, D. Kamm¹, M. Kiekebusch⁶, S. Kraus⁴, D. Le Contel¹, J.-M. Le Contel¹, T. Lesourd¹¹, B. Lopez¹, M. Lopez¹¹, Y. Magnard³, A. Marconi⁵, G. Mars¹, G. Martinot-Lagarde^{11, 1}, P. Mathias¹, P. Mège³, J.-L. Monin³, D. Mouillet^{3, 12}, E. Nussbaum⁴, K. Ohnaka⁴, J. Pacheco¹, C. Perrier³, Y. Rabbia¹, S. Rebattu¹, F. Reynaud¹³, A. Richichi¹⁴, A. Robini², M. Sacchettini³, D. Schertl⁴, M. Schöller⁶, W. Solscheid⁴, P. Stefanini⁵, M. Tallon⁹, I. Tallon-Bosc⁹, D. Tasso¹, L. Testi⁵, F. Vakili², O. von der Lühe¹⁵, J.-C. Valtier¹, M. Vannier^{2, 6, 16}, and N. Ventura³

¹ Laboratoire Gemini, UMR 6203 Observatoire de la Côte d'Azur/CNRS, BP 4229, 06304 Nice Cedex 4, France
² Laboratoire Universitaire d'Astrophysique de Nice, UMR 6525 Université de Nice - Sophia Antipolis/CNRS, Parc Valrose, 06108 Nice Cedex 2, France
³ Laboratoire d'Astrophysique de Grenoble, UMR 5571 Université Joseph Fourier/CNRS, BP 53, 38041 Grenoble Cedex 9, France
⁴ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁵ INAF-Osservatorio Astrofisico di Arcetri, Istituto Nazionale di Astrofisica, Largo E. Fermi 5, 50125 Firenze, Italy
⁶ European Southern Observatory, Casilla 19001, Santiago 19, Chile
⁷ Instituut voor Sterrenkunde, KU-Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
⁸ ONERA/DOTA, 29 av de la Division Leclerc, BP 72, 92322 Chatillon Cedex, France
⁹ Centre de Recherche Astronomique de Lyon, UMR 5574 Université Claude Bernard/CNRS, 9 avenue Charles André, 69561 Saint Genis Laval Cedex, France
¹⁰ Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹¹ Division Technique INSU/CNRS UPS 855, 1 place Aristide Briand, 92195 Meudon Cedex, France
¹² Laboratoire Astrophysique de Toulouse, UMR 5572 Université Paul Sabatier/CNRS, BP 826, 65008 Tarbes Cedex, France
¹³ IRCOM, UMR 6615 Université de Limoges/CNRS, 123 avenue Albert Thomas, 87060 Limoges Cedex, France
¹⁴ European Southern Observatory, Karl Schwarzschild Strasse 2, 85748 Garching, Germany
¹⁵ Kiepenheuer Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany
¹⁶ Departamento de Astronomia, Universidad de Chile, Chile

(Received 11 April 2006 / Accepted 25 October 2006 )

Abstract
Aims.We study the geometry and kinematics of the circumstellar environment of the Be star $\kappa$ CMa in the Br $\gamma$ emission line and its nearby continuum.
Methods.We use the AMBER/VLTI instrument operating in the K band, which provides a spatial resolution of about 6 mas with a spectral resolution of 1500, to study the kinematics within the disk and to infer its rotation law. To obtain more kinematical constraints we also use a high spectral resolution Pa $\beta$ line profile obtain in December 2005 at the Observatorio do Pico do Dios, Brazil and we compile V/R line profile variations and spectral energy distribution data points from the literature.
Results.Using differential visibilities and differential phases across the Br $\gamma$ line we detect an asymmetry in the disk. Moreover, we found that $\kappa$ CMa seems difficult to fit within the classical scenario for Be stars, illustrated recently by $\alpha$ Arae observations, i.e. a fast rotating B star close to its breakup velocity surrounded by a Keplerian circumstellar disk with an enhanced polar wind. We discuss the possibility that $\kappa$ CMa is a critical rotator with a Keplerian rotating disk and examine whether if the detected asymmetry can be interpreted within the "one-armed" viscous disk framework.

Key words: techniques: high angular resolution -- techniques: interferometric -- stars: emission-line, Be -- stars: individual: Keplerian rotation -- stars: individual: $\kappa$ CMa -- stars: circumstellar matter

An asymmetry detected in the disk of Canis Majoris with AMBER/VLTI

An asymmetry detected in the disk of $\kappa$ Canis Majoris with AMBER/VLTI