On the stratified dust distribution of the GG Tauri circumbinary ring

¹ Laboratoire d'Astrophysique de Grenoble, CNRS/UJF UMR 5571, 414 rue de la Piscine, BP 53, 38041 Grenoble Cedex 9, France e-mail: [pinte;menard;duchene]@obs.ujf-grenoble.fr
² School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
³ Université de Lyon, 69003 Lyon, Université Lyon 1, 69622 Villeurbanne, CNRS, UMR 5574, Centre de Recherche Astrophysique de Lyon; École Normale Supérieure de Lyon, 46 allée d'Italie, 69364 Lyon Cedex 07, France e-mail: [Laure.Barriere;Jean-Francois.Gonzalez]@ens-lyon.fr
⁴ Institute of Astronomy, ETH Zurich, Schafmattstrasse 16, HPT D19, 8093 Zurich, Switzerland

Received: 19 January 2007
Accepted: 19 April 2007

Abstract

Aims.Our objective is to study the vertical dust distribution in the circumbinary ring of the binary system GG Tau and to search for evidence of stratification, one of the first steps expected to occur during planet formation.

Methods.We present a simultaneous analysis of four scattered light images spanning a range of wavelength from 800 nm to 3800 nm and compare them with (i) a parametric prescription for the vertical dust stratification, and (ii) with the results of SPH bi-fluid hydrodynamic calculations.

Results.The parametric prescription and hydrodynamical calculations of stratification both reproduce the observed brightness profiles well. These models also provide a correct match for the observed star/ring integrated flux ratio. Another solution with a well-mixed, but “exotic”, dust size distribution also matches the brightness profile ratios but fails to match the star/ring flux ratio. These results give support to the presence of vertical stratification of the dust in the ring of GG Tau and also allow us to predict the presence of a radial stratification.