GG Tauri : the fifth element

E. Di Folco (1) , Anne Dutrey (1) , J. -B. Le Bouquin (2) , S. Lacour (3) , J. -P. Berger (4) , R. Köhler , S. Guilloteau (1) , V. Piétu (2) , J. Bary , T. Beck , H. Beust , E. Pantin (5, 6)

1 AMOR 2014
2 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
3 UR TSAN - Technologies pour la sécurité et les performances des agroéquipements
4 ESO - European Southern Observatory
5 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
6 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation

We aim at unveiling the observational imprint of physical mechanisms that govern planetary formation in young, multiple systems. In particular, we investigate the impact of tidal truncation on the inner circumstellar disks. We observed the emblematic system GG Tau at high-angular resolution: a hierarchical quadruple system composed of low-mass T Tauri binary stars surrounded by a well-studied, massive circumbinary disk in Keplerian rotation. We used the near-IR 4-telescope combiner PIONIER on the VLTI and sparse-aperture-masking techniques on VLT/NaCo to probe this proto-planetary system at sub-AU scales. We report the discovery of a significant closure-phase signal in H and Ks bands that can be reproduced with an additional low-mass companion orbiting GG Tau Ab, at a (projected) separation rho = 31.7 +/- 0.2mas (4.4 au) and PA = 219.6 +/- 0.3deg. This finding offers a simple explanation for several key questions in this system, including the missing-stellar-mass problem and the asymmetry of continuum emission from the inner dust disks observed at millimeter wavelengths. Composed of now five co-eval stars with 0.02 <= Mstar <= 0.7 Msun, the quintuple system GG Tau has become an ideal test case to constrain stellar evolution models at young ages (few 10^6yr).

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]; Planétologie et astrophysique de la terre [astro-ph.EP]; Planétologie et astrophysique de la terre [astro-ph.EP]

E. Di Folco, Anne Dutrey, J. -B. Le Bouquin, S. Lacour, J. -P. Berger, et al.. GG Tauri : the fifth element. Astronomy and Astrophysics - A&A, 2014, 565, pp.id.L2. ⟨10.1051/0004-6361/201423675⟩. ⟨hal-00976559⟩