The structure of protoplanetary disks surrounding three young intermediate mass stars^*

I. Resolving the disk rotation in the [OI] 6300 Å  line

¹ European Southern Observatory, Karl-Schwarzschild-Str.2, 85748 Garching bei München, Germany e-mail: gvanderp@eso.org
² Sterrenkundig Instituut “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
³ Dipartimento di Astronomia, Universitá Degli Studi Di Padova, Vicolo Dell' Osservatorio 2, 35122 Padova, Italy
⁴ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

Received: 18 October 2007
Accepted: 4 February 2008

Abstract

We present high-spectral-resolution, optical spectra of three young, intermediate-mass stars, in all of which we spectrally resolve the 6300 Å  [OI] emission line. Two of these have a double-peaked line-profile. We attempt to fit these data using a simple model of [OI] emission, which is generated by photo-dissociation of OH molecules, in the upper layer of a circumstellar disk, by stellar UV radiation. We translate the Doppler-broadened [OI] emission line profile, into a measure of emission, as a function of distance from the central star. The resulting spectra are in agreement with the expected disk shapes derived from their spectral energy distribution. We find evidence for shadowing by an inner rim in the disk surrounding HD 101412, and observe a flaring disk structure in HD 179218, while the [OI] spectrum of HD 135344 B is more complex. The [OI] emission starts for all three targets at velocities corresponding to their dust sublimation radius and extends up to radii of 10–90 AU. This shows that this method can be a valuable tool in the future investigation of circumstellar disks.