Signs of late infall and possible planet formation around DR Tau using VLT/SPHERE and LBTI/LMIRCam^★,★★

¹ INAF Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
e-mail: dino.mesa@inaf.it
² Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
³ Large Binocular Telescope Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA
⁴ Steward Observatory, Department of Astronomy, University of Arizona, 993 N. Cherry Ave, Tucson, AZ 85721, USA
⁵ Institute for Astronomy, University of Edinburgh, EH9 3HJ, Edinburgh, UK
⁶ Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
⁷ INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125, Firenze, Italy
⁸ INAF, Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
⁹ Astronomy Department, University of Michigan, Ann Arbor, MI 48109, USA
¹⁰ Institute for Particle Physics and Astrophysics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
¹¹ Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
¹² Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
¹³ CRAL, UMR 5574, CNRS, Université de Lyon, Ecole Normale Sup,erieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
¹⁴ INAF-Osservatorio Astronomico di Roma, Via di Frascati 33, 00078 Monte Porzio Catone, Italy
¹⁵ Institute of Astronomy, KU Leuven, Celestijnlaan 200D, 3001 Leuven, Belgium
¹⁶ Department of Astronomy, Stockholm University, AlbaNova University Center, 109 91 Stockholm, Sweden
¹⁷ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Konkoly-Thege Miklós út 15-17, 1121 Budapest, Hungary
¹⁸ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹⁹ Department of Physics and Astronomy “Galileo Galilei”, University of Padova, Italy
²⁰ Núcleo de Astronomía, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
²¹ Escuela de Ingeniería Industrial, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
²² LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne-Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 Place Jules Janssen, 92195 Meudon, France
²³ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
²⁴ Geneva Observatory, University of Geneva, Chemin des Mailettes 51, 1290 Versoix, Switzerland
²⁵ Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaiso, Av. Gran Bretaña 1111, Valparaíso, Chile
²⁶ Núcleo Milenio Formación Planetaria – NPF, Universidad de Valparaiso, Av. Gran Bretaña 1111, Valparaíso, Chile
²⁷ DOTA, ONERA, Université Paris Saclay, 91123 Palaiseau, France

Received: 14 September 2021
Accepted: 1 November 2021

Abstract

Context. Protoplanetary disks around young stars often contain substructures like rings, gaps, and spirals that could be caused by interactions between the disk and forming planets.

Aims. We aim to study the young (1–3 Myr) star DR Tau in the near-infrared and characterize its disk, which was previously resolved through submillimeter interferometry with ALMA, and to search for possible substellar companions embedded into it.

Methods. We observed DR Tau with VLT/SPHERE both in polarized light (H broad band) and total intensity (in Y, J, H, and K spectral bands). We also performed L′ band observations with LBTI/LMIRCam on the Large Binocular Telescope (LBT). We applied differential imaging techniques to analyze both the polarized data, using dual beam polarization imaging, and the total intensity data, using angular and spectral differential imaging.

Results. We found two previously undetected spirals extending north-east and south of the star, respectively. We further detected an arc-like structure north of the star. Finally a bright, compact and elongated structure was detected at a separation of 303 ± 10 mas and a position angle 21.2 ± 3.7 degrees, just at the root of the north-east spiral arm. Since this feature is visible both in polarized light and total intensity and has a blue spectrum, itis likely caused by stellar light scattered by dust.

Conclusions. The two spiral arms are at different separations from the star, have very different pitch angles, and are separated by an apparent discontinuity, suggesting they might have a different origin. The very open southern spiral arm might be caused by infalling material from late encounters with cloudlets into the formation environment of the star itself. The compact feature could be caused by interaction with a planet in formation still embedded in its dust envelope and it could be responsible for launching the north–east spiral. We estimate a mass of the putative embedded object of the order of few M_Jup.