The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution

R. Garcia Lopez , K. Perraut (1) , A. Caratti O Garatti , B. Lazareff (1) , J. Sanchez-Bermudez (2) , M. Benisty (1) , C. Dougados (1) , L. Labadie (1) , W. Brandner (3) , J. Garcia , Th. Henning (3) , P. Ray (4) , R. Abuter (2) , A. Amorim , N. Anugu , J. Berger , H. Bonnet , A. Buron , P. Caselli (5) , Y. Clenet (6) , Vincent Coudé Du Forestol (6) , W. de Wit , C. Deen , F. Delplancke-Ströbele , J. Dexter , A. Eckart (7) , F. Eisenhauer (8) , C. Garcia , E. Gendron (6) , R. Genzel (8) , S. Gillessen (8) , X. Haubois , M. Haug , F. Haussmann , S. Hippler , Z. Hubert (6) , A. Hummel (9) , M. Horrobin (10) , L. Jocou (1) , S. Kellner , P. Kervella (6) , M. Kulas , J. Kolb , S. Lacour (11) , B. Le Bouquin , P. Lena (6) , M. Lippa , A. Merand (2) , E. Müller , T. Ott (12) , J. Panduro , T. Paumard (6) , G. Perrin (6) , O. Pfuhl (8) , A. Ramírez (13) , C. Rau (14) , R. Rohloff , G. Rousset (6) , S. Scheithauer , M. Scholler (15) , C. Straubmeier (16) , E. Sturm (8) , W. Thi , E. van Dishoeck (17) , F. Vincent (6) , I. Waisberg , I. Wank , E. Wieprecht , M. Wiest , E. Wiezorrek (8) , J. Woillez (2) , S. Yazici , G. Zins (1)

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
2 ESO - European Southern Observatory
3 MPIA - Max-Planck-Institut für Astronomie
4 DALEMBERT - Institut Jean Le Rond d'Alembert
5 OAA - INAF - Osservatorio Astrofisico di Arcetri
6 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
7 MPIFR - Max-Planck-Institut für Radioastronomie
8 MPE - Max Planck Institute for Extraterrestrial Physics
9 Mayo Clinic [Rochester]
10 GEPI - Galaxies, Etoiles, Physique, Instrumentation
11 INRETS/LTE - Laboratoire Transport et Environnement
12 SSC - Swedish Space Corporation
13 CINVESTAV-IPN - Departamento de Control Automático
14 DIAMOND Light source
15 IBCP - Institut de biologie et chimie des protéines [Lyon]
16 Universität zu Köln = University of Cologne
17 Leiden Observatory [Leiden]

Aims. To investigate the inner regions of protoplanetary discs, we performed near-infrared interferometric observations of the classical T Tauri binary system S CrA.Methods. We present the first VLTI-GRAVITY high spectral resolution (R ~ 4000) observations of a classical T Tauri binary, S CrA (composed of S CrA N and S CrA S and separated by ~1.̋4), combining the four 8m telescopes in dual-field mode. Results. Our observations in the near-infrared K-band continuum reveal a disc around each binary component, with similar half-flux radii of about 0.1 au at d ~ 130 pc, inclinations (i = 28 ± 3° and i = 22 ± 6°), and position angles (PA = 0°± 6° and PA = –2°± 12°), suggesting that they formed from the fragmentation of a common disc. The S CrA N spectrum shows bright He i and Brγ line emission exhibiting inverse P Cygni profiles, typically associated with infalling gas. The continuum-compensated Brγ line visibilities of S CrA N show the presence of a compact Brγ emitting region whose radius is about ~0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue- and red-shifted Brγ line components is marginally detected.Conclusions. The presence of an inverse P Cygni profile in the He i and Brγ lines, along with the tentative detection of a slightly larger size of the blue-shifted Brγ line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N.

Mots clés: stars: formation; circumstellar matter; ISM: jets and outflows; ISM: individual objects: S CrA; infrared: ISM; techniques: interferometric

Domaines: Astrophysique [astro-ph]; Astrophysique [astro-ph]

R. Garcia Lopez, K. Perraut, A. Caratti O Garatti, B. Lazareff, J. Sanchez-Bermudez, et al.. The wind and the magnetospheric accretion onto the T Tauri star S Coronae Australis at sub-au resolution. Astronomy and Astrophysics - A&A, 2017, 608, pp.A78. ⟨10.1051/0004-6361/201731058⟩. ⟨obspm-02190736⟩