The Structure of Protoplanetary Disks Surrounding Three Young Intermediate Mass Stars. I. Resolving the disk rotation in the [OI] 6300 \AA line

TL;DR

This study uses high-resolution optical spectra to analyze the [OI] 6300 Å emission in three young intermediate-mass stars, revealing disk structures and dynamics consistent with models of photo-dissociation and disk geometry.

Contribution

It provides the first spectrally resolved [OI] emission profiles for these stars, linking emission features to disk structure and dynamics, and demonstrating a new method for studying circumstellar disks.

Findings

[OI] emission originates near dust sublimation radius.

Detected shadowing effects and flaring disk structures.

Emission extends from inner rim to 90 AU, revealing disk geometry.

Abstract

We present high spectral resolution optical spectra of three young intermediate mass stars, in all of which we spectrally resolve the 6300 Angstrom [OI] emission line. Two of these have a double peaked line profile. We fit these data with a simple model of the [OI] emission caused by photo-dissociation of OH molecules in the upper layer of a circumstellar disk by stellar UV radiation and thus translate the Doppler broadened [OI] emission profile into an amount of emission as a function of distance from the central star. The resulting spectra are in agreement with the expected disk shapes as derived from their spectral energy distribution. We find evidence for shadowing by an inner rim in the disk surrounding HD101412 and see a flaring disk structure in HD179218 while the [OI] spectrum of HD135344 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.