Dynamics of the young multiple system GG Tauri

II. Relation between the stellar system and the circumbinary disk

¹ Laboratoire d'Astrophysique de Grenoble, Université J. Fourier, BP 53, 38041 Grenoble Cedex 9, France e-mail: herve.beust@obs.ujf-grenoble.fr
² Laboratoire d'Astrodynamique, d'Astrophysique et d'Aéronomie de Bordeaux, 2 rue de l'Observatoire, BP 89, 33270 Floirac, France

Received: 31 March 2005
Accepted: 15 August 2005

Abstract

The quadruple young system GG Tauri is an example of a multiple T Tauri system. Its consists of two binaries, the brighter one (GG Tau A) being surrounded by a ring-shape circumbinary disk. In a recent paper, we performed a dynamical study of circumbinary and showed that there is an apparent discrepancy between the orbital fit of GG Tau A and the observed inner edge of the disk. In this paper, we now investigate the dynamics of the whole quadruple system together with the disk. We show that it is possible to design an orbital configuration between the two binaries in such a way that the outer profile of the circumbinary ring may be explained by tidal interaction with repeated periastron passages of the outer binary GG Tau B. We show that the observed characteristics of the disk are not compatible with some orbital configurations, such as those giving rise to the Kozai resonance. Surprisingly, the outer binary GG Tau B appears only marginally stable against tidal disruption by GG Tau A. GG Tau B appears stable only if its internal orbit is retrograde with respect to the motion of its center of mass around GG Tau A. We also find that the CB disk should be almost coplanar with the inner binary.