Multiwavelength interferometric observations and modeling of circumstellar disks^⋆,⋆⋆

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Ludwig-Maximilians-Universität, Universitäts-Sternwarte München, Scheinerstraße 1, 81679 München, Germany
³ Universität zu Köln, I. Physikalisches Institut, Zülpicher Straße 77, 50937 Köln, Germany
⁴ Universität Kiel, Institut für Theoretische Physik und Astrophysik, Leibnizstraße 15, 24098 Kiel, Germany
⁵ MTA Research Center for Astronomy and Earth Sciences, Konkoly Thege Miklós Astronomical Institute, 1525 Budapest, Hungary

Received: 8 August 2012
Accepted: 4 April 2013

Abstract

Aims. We investigate the structure of the innermost region of three circumstellar disks around pre-main sequence stars HD 142666, AS 205 N, and AS 205 S. We determine the inner radii of the dust disks and, in particular, search for transition objects where dust has been depleted and inner disk gaps have formed at radii of a few tenths of AU up to several AU.

Methods. We performed interferometric observations with IOTA, AMBER, and MIDI in the infrared wavelength ranges 1.6−2.5   μm and 8−13   μm with projected baseline lengths between 25   m and 102   m. The data analysis was based on radiative transfer simulations in 3D models of young stellar objects (YSOs) to reproduce the spectral energy distribution and the interferometric visibilities simultaneously. Accretion effects and disk gaps could be considered in the modeling approach. Results from previous studies restricted the parameter space.

Results. The objects of this study were spatially resolved in the infrared wavelength range using the interferometers. Based on these observations, a disk gap could be found for the source HD 142666 that classifies it as transition object. There is a disk hole up to a radius of R_in = 0.30   AU and a (dust-free) ring between 0.35   AU and 0.80   AU in the disk of HD 142666. The classification of AS 205 as a system of classical T Tauri stars could be confirmed using the canonical model approach, i.e., there are no hints of disk gaps in our observations.