1 Université Grenoble Alpes, IPAG, 38000 Grenoble, France ;
CNRS, IPAG, 38000 Grenoble, France
2 Institute of Astronomy, Madingley Road, Cambridge CB3 OHA, UK
3 LESIA, Observatoire de Paris, CNRS, Université Pierre et Marie Curie Paris 6, Université Denis Diderot Paris 7, 5 place Jules Janssen, 92195 Meudon, France
4 Departamento de Astronomìa, Universidad de Chile, Casilla 36-D, Santiago, Chile
5 ESO, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile
6 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland
7 Sterrenkundig Instituut Anton Pannekoek, Science Park 904, 1098 XH Amsterdam, The Netherlands
8 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
9 Max-Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
10 Institute of Theoretical Astrophysics, Heidelberg University, Albert-Ueberle-Strasse 2, 69120 Heidelberg, Germany
11 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
12 Eureka Scientific and Goddard Space Flight Center, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA
13 Centro de Astrobiología (INTA-CSIC); ESAC Campus, PO Box 78, 28691 Villanueva de la Canada, Spain
14 Department of Physics & Astronomy, Rice University, 6100 Main Street, Houston, TX 77005, USA
15 Observatoire de Lyon, Centre de Recherche Astrophysique de Lyon, École Normale Supérieure de Lyon, CNRS, Université Lyon 1, UMR 5574, 9 avenue Charles André, 69230 Saint-Genis Laval, France
16 UMI-FCA, CNRS/INSU, France (UMI 3386), and Dept. de Astronomía, Universidad de Chile, Santiago, Chile
17 Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot, IRFU/SAp, 91191 Gif-sur-Yvette, France
18 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Received: 3 March 2015
Accepted: 17 May 2015
Context. The study of dynamical processes in protoplanetary disks is essential to understand planet formation. In this context, transition disks are prime targets because they are at an advanced stage of disk clearing and may harbor direct signatures of disk evolution.
Aims. We aim to derive new constraints on the structure of the transition disk MWC 758, to detect non-axisymmetric features and understand their origin.
Methods. We obtained infrared polarized intensity observations of the protoplanetary disk MWC 758 with VLT/SPHERE at 1.04 μm to resolve scattered light at a smaller inner working angle (0.093′′) and a higher angular resolution (0.027′′) than previously achieved.
Results. We observe polarized scattered light within 0.53′′ (148 au) down to the inner working angle (26 au) and detect distinct non-axisymmetric features but no fully depleted cavity. The two small-scale spiral features that were previously detected with HiCIAO are resolved more clearly, and new features are identified, including two that are located at previously inaccessible radii close to the star. We present a model based on the spiral density wave theory with two planetary companions in circular orbits. The best model requires a high disk aspect ratio (H/r ~ 0.20 at the planet locations) to account for the large pitch angles which implies a very warm disk.
Conclusions. Our observations reveal the complex morphology of the disk MWC 758. To understand the origin of the detected features, the combination of high-resolution observations in the submillimeter with ALMA and detailed modeling is needed.
Key words: techniques: high angular resolution / protoplanetary disks
Appendices are available in electronic form at http://www.aanda.org
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© ESO, 2015