Revealing the inclined circumstellar disk in the UX Orionis system KK Ophiuchi
Astronomy and Astrophysics
EDP Sciences for European Southern Observatory (ESO)
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.
A. Kreplin was supported for this research through a stipend from the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Universities of Bonn and Cologne. V.G. and L.T. were supported in part by the grant of the Presidium of RAS P 21 and grant NSh. – 1625.2012.2. They also thank the Max-Planck-Society for the support during their stay in Bonn. This research has made use of NASA’s Astrophysics Data System Bibliographic Services.
This is the final version of the article. Available from EDP Sciences via the DOI in this record.
Vol. 551, article A21