Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Scattered light detection of a possible disk wind in RY Tau

¹ Anton Pannekoek Institute for Astronomy (API), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
e-mail: p.g.valegard@uva.nl
² Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
³ Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
⁴ University of Grenoble Alps, CNRS, IPAG, 38000 Grenoble, France
⁵ University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 Munich, Germany
⁶ Exzellenzcluster ORIGINS, Boltzmannstr. 2, 85748 Garching, Germany
⁷ Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy
⁸ INAF, Osservatorio Astrofísico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
⁹ European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago, Chile
¹⁰ Centre de Recherche Astrophysique de Lyon, CNRS, UCBL, ENS Lyon, UMR 5574, 69230, Saint-Genis-Laval, France
¹¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
¹² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
¹³ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
¹⁴ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
¹⁵ Institute for Mathematics, Astrophysics & Particle Physics, Radboud University, PO Box 9010, MC 62, 6500 GL Nijmegen, The Netherlands
¹⁶ SRON, Sorbonnelaan 2, 3484 CA Utrecht, The Nederlands
¹⁷ Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA

Received: 11 May 2022
Accepted: 4 August 2022

Abstract

Context. Disk winds are an important mechanism for accretion and disk evolution around young stars. The accreting intermediate-mass T-Tauri star RY Tau has an active jet and a previously known disk wind. Archival optical and new near-infrared observations of the RY Tau system show two horn-like components stretching out as a cone from RY Tau. Scattered light from the disk around RY Tau is visible in the near-infrared, but not seen at optical wavelengths. In the near-infrared, dark wedges separate the horns from the disk, indicating that we may see the scattered light from a disk wind.

Aims. We aim to test the hypothesis that a dusty disk wind could be responsible for the optical effect in which the disk around RY Tau is hidden in the I band, but visible in the H band. This could be the first detection of a dusty disk wind in scattered light. We also want to constrain the grain size and dust mass in the wind and the wind-launching region.

Methods. We used archived Atacama-Large-Millimetre-Array (ALMA) and Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) I band observations combined with newly acquired SPHERE H band observations and available literature to build a simple geometric model of the RY Tau disk and disk wind. We used Monte Carlo radiative transfer modelling MCMax3D to create comparable synthetic observations that test the effect of a dusty wind on the optical effect in the observations. We constrained the grain size and dust mass needed in the disk wind to reproduce the effect from the observations.

Results. A model geometrically reminiscent of a dusty disk wind with small micron to sub-micron-sized grains elevated above the disk can reproduce the optical effect seen in the observations. The mass in the obscuring component of the wind has been constrained to 1 × 10⁻⁹ M_⊙ ≤ M ≤ 5 × 10⁻⁸ M_⊙, which corresponds to a mass-loss rate in the wind of about ~1 × 10⁻⁸ M_⊙ yr⁻¹.

Conclusions. A simple model of a disk wind with micron to sub-micron-sized grains elevated above the disk is able to prevent stellar radiation to scatter in the disk at optical wavelengths while allowing photons to reach the disk in the near-infrared. Estimates of mass-loss rate correspond to previously presented theoretical models and points towards the idea that a magneto-hydrodynamic-type wind is the more likely scenario.