Volume 551, March 2013
|Number of page(s)||6|
|Section||Interstellar and circumstellar matter|
|Published online||12 February 2013|
Revealing the inclined circumstellar disk in the UX Orionis system KK Ophiuchi⋆
1 Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2 Havard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138, USA
3 Pulkovo Observatory of RAS, Pulkovskoe shosse 65, 196140 St. Petersburg, Russia
4 V.V. Sobolev Astronomical Institute, St. Petersburg University, St. Petersburg, Russia
5 INAF Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy
6 Université Joseph Fourier (UJF) – Grenoble 1/CNRS-INSU, Institut de Planételogie et d’Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France
7 Laboratoire Lagrange, UMR 7293 UNS-CNRS-OCA, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France
Received: 28 November 2012
Accepted: 4 January 2013
Aims. We study the inner sub-AU region of the circumstellar environment of the UX Ori-type star KK Oph with near-infrared VLTI/AMBER interferometry. We are particularly interested in the inclination of the star-disk system, and we use this information to test the current standard picture for UX Ori stars.
Methods. We recorded spectrally dispersed (R ~ 35) interferograms in the near-infrared H and K bands with the VLTI/AMBER instrument. The derived visibilities, closure phases, and the spectral energy distribution of KK Oph were compared with two-dimensional geometric and radiative transfer models (RADMC).
Results. We obtained visibilities at four different position angles. Using two-dimensional geometric models, we derive an axis ratio ~3.0 corresponding to an inclination of ~70°. A fitted inclined ring model leads to a ring radius of 2.8 ± 0.2 mas, corresponding to 0.44 ± 0.03 AU at a distance of 160 pc, which is larger than the dust sublimation radius of ~0.1 AU predicted for a dust sublimation temperature of 1500 K. Our derived two-dimensional RADMC model consists of a circumstellar disk with an inclination angle of ~70° and an additional dust envelope.
Conclusions. The finding of an ~70° inclined disk around KK Oph is consistent with the prediction that UX Ori objects are seen under large inclination angles, and orbiting clouds in the line of sight cause the observed variability. Furthermore, our results suggest that the orbit of the companion KK Oph B and the disk plane are coplanar.
Key words: techniques: interferometric / stars: pre-main sequence / stars: individual: KK Ophiuchi / circumstellar matter
© ESO, 2013
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