stars: individual: T Cha; protoplanetary disks; techniques: polarimetric; radiative transfer; scattering; circumstellar matter; Astrophysics - Earth and Planetary Astrophysics
Abstract :
[en] Context. The transition disk around the T Tauri star T Cha possesses a large gap, making it a prime target for high-resolution imaging in the context of planet formation. <BR /> Aims: We aim to find signs of disk evolutionary processes by studying the disk geometry and the dust grain properties at its surface, and to search for companion candidates. <BR /> Methods: We analyze a set of VLT/SPHERE data at near-infrared and optical wavelengths. We performed polarimetric imaging of T Cha with IRDIS (1.6 μm) and ZIMPOL (0.5-0.9 μm), and obtained intensity images from IRDIS dual-band imaging with simultaneous spectro-imaging with IFS (0.9-1.3 μm). <BR /> Results: The disk around T Cha is detected in all observing modes and its outer disk is resolved in scattered light with unprecedented angular resolution and signal-to-noise. The images reveal a highly inclined disk with a noticeable east-west brightness asymmetry. The significant amount of non-azimuthal polarization signal in the U[SUB]φ[/SUB] images, with a U[SUB]φ[/SUB]/Q[SUB]φ[/SUB] peak-to-peak value of 14%, is in accordance with theoretical studies on multiple scattering in an inclined disk. Our optimal axisymmetric radiative transfer model considers two coplanar inner and outer disks, separated by a gap of 0.̋28 ( 30 au) in size, which is larger than previously thought. We derive a disk inclination of 69 deg and PA of 114 deg. In order to self-consistently reproduce the intensity and polarimetric images, the dust grains, responsible for the scattered light, need to be dominated by sizes of around ten microns. A point source is detected at an angular distance of 3.5'' from the central star. It is, however, found not to be co-moving. <BR /> Conclusions: We confirm that the dominant source of emission is forward scattered light from the near edge of the outer disk. Our point source analysis rules out the presence of a companion with mass larger than 8.5 M[SUB]jup[/SUB] between 0.̋1 and 0.̋3. The detection limit decreases to 2 M[SUB]jup[/SUB] for 0.̋3 to 4.0''. <P />Based on observations made with European Southern Observatory (ESO) telescopes at the Paranal Observatory in Chile, under program IDs 095.C-0298(B), 096.C-0248(B) and 096.C-0248(C).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Pohl, A.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; Heidelberg University, Institute of Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120, Heidelberg, Germany
Sissa, E.; INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy ; Dipartimento di Fisica e Astronomia "G. Galilei", Universita' degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy
Langlois, M.; CRAL, UMR 5574, CNRS, Université Lyon 1, 9 avenue Charles André, 69561, Saint Genis Laval Cedex, France ; Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388, Marseille, France
Müller, A.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; Heidelberg University, Institute of Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120, Heidelberg, Germany
Ginski, C.; Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden, The Netherlands ; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
van Holstein, R. G.; Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden, The Netherlands
Vigan, A.; Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388, Marseille, France
Maire, Anne-Lise ; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; Heidelberg University, Institute of Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120, Heidelberg, Germany
Henning, Th; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany
Olofsson, J.; Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile ; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; ICM nucleus on protoplanetary disks, Protoplanetary discs in ALMA Early Science, Universidad de Valparaíso, Valparaíso, Chile
van Boekel, R.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany
Benisty, M.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Biller, B.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill View, Edinburgh, EH9 3HJ, UK
Boccaletti, A.; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195, Meudon, France
Chauvin, G.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Daemgen, S.; Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
de Boer, J.; Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden, The Netherlands
Dominik, C.; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
Garufi, Antonio; Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
Janson, M.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany ; Department of Astronomy, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden
Kral, Q.; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
Ménard, F.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Pinte, C.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Stolker, T.; Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
Szulágyi, J.; Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
Zurlo, A.; Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, 13388, Marseille, France ; Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile ; Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
Bonnefoy, M.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Cheetham, A.; Observatoire Astronomique de l'Université de Genève, 51 Ch. des Maillettes, 1290, Versoix, Switzerland
Cudel, M.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Feldt, M.; Max Planck Institute for Astronomy, Königstuhl 17, 69117, Heidelberg, Germany
Kasper, M.; European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748, Garching, Germany
Lagrange, A.-M.; Univ. Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Perrot, C.; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195, Meudon, France
Wildi, F.; Observatoire Astronomique de l'Université de Genève, 51 Ch. des Maillettes, 1290, Versoix, Switzerland)
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