SPHERE view of the jet and the envelope of RY Tauri^★

¹ INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
e-mail: agarufi@arcetri.astro.it
² INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (RM), Italy
³ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
⁴ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁵ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁶ Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109-1107, USA
⁷ Institute for Particle Physics and Astrophysics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
⁸ Department of Physics, University of Oxford, Oxford, UK
⁹ Institute for Astronomy, University of Edinburgh, EH9 3HJ, Edinburgh, UK
¹⁰ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
¹¹ Geneva Observatory, University of Geneva, Ch. des Maillettes 51, 1290 Versoix, Switzerland
¹² CRAL, CNRS, Université Lyon 1, 9 avenue Charles André, 69561 Saint Genis Laval Cedex, France
¹³ Università degli Studi di Padova, dipartimento di Fisica e Astronomia, vicolo dell’osservatorio 3, 35122 Padova, Italy
¹⁴ STAR Institute, University of Liège, Allée du Six Août 19c, 4000 Liège, Belgium
¹⁵ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
¹⁶ Núcleo Milenio Formación Planetaria – NPF, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso, Chile
¹⁷ Aix Marseille Université, CNRS, LAM – Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
¹⁸ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
¹⁹ Escuela de Ingeniería Industrial, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile

Received: 26 March 2019
Accepted: 17 June 2019

Abstract

Context. Jets are rarely associated with pre-main sequence intermediate-mass stars. This contrasts with the frequent detection of jets in lower mass or younger stars. Optical and near-IR observations of jet-driving sources are often hindered by the presence of a natal envelope.

Aims. Jets around partly embedded sources are a useful diagnostic to constrain the geometry of the concealed protoplanetary disk. We intend to clarify how the jet-driving mechanisms are affected by both spatial anisotropies and episodic variations at the (sub-)au scale from the star.

Methods. We obtained a rich set of high-contrast VLT/SPHERE observations from 0.6 to 2.2 μm of the young intermediate-mass star RY Tau. Given the proximity to the Sun of this source, our images have the highest spatial resolution ever obtained for an atomic jet (down to ~4 au).

Results. Optical observations in polarized light show no sign of the protoplanetary disk detected by ALMA. Instead, we observed a diffuse signal resembling a remnant envelope with an outflow cavity. The jet is detected in the Hα, [S II] at 1.03 μm, He I at 1.08 μm, and [Fe II] lines in the 1.25 μm and 1.64 μm. The jet appears to be wiggling and its radial width increasing with the distance is complementary to the shape of the outflow cavity suggesting a strong interaction with jet and envelope. Through the estimated tangential velocity (~100 km s⁻¹), we revealed a possible connection between the launching time of the jet substructures and the stellar activity of RY Tau.

Conclusions. RY Tau is at an intermediate stage toward the dispersal of the natal envelope. This source shows episodic increases of mass accretion and ejection similarly to other known intermediate-mass stars. The amount of observed jet wiggle is consistent with the presence of a precessing disk warp or misaligned inner disk that would be induced by an unseen planetary or sub-stellar companion at sub- or few-au scales respectively. The high disk mass of RY Tau and of two other jet-driving intermediate-mass stars, HD 163296 and MWC480, suggests that massive, full disks are more efficient at launching prominent jets.