Volume 564, April 2014
|Number of page(s)||22|
|Section||Interstellar and circumstellar matter|
|Published online||14 April 2014|
On the structure of the transition disk around TW Hydrae
1 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
2 Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
3 National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
4 CNRS/UJF Grenoble 1, UMR 5274, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), 38041 Grenoble, France
5 LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France
6 Astronomical Institute “Anton Pannekoek”, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands
7 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
8 Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109, USA
9 Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
10 Joint ALMA Observatory, Av. Alonso de Córdova 3107, 7630000 Vitacura, Santiago, Chile
11 The Netherlands Institute for Radio Astronomy (ASTRON), 7990 AA Dwingeloo, The Netherlands
12 School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews KY16 9SS, UK
13 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands
14 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106, USA
15 UMI-FCA, CNRS/INSU France (UMI 3386), and Departamento de Astronomía, Universidad de Chile, Casilla 36- D Santiago, Chile
16 Department of Astronomy, University of Maryland, College Park, MD 20742, USA
17 European Southern Observatory, Karl Schwarzschild Str. 2, 85748 Garching, Germany
18 INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
Received: 31 October 2013
Accepted: 21 February 2014
Context. For over a decade, the structure of the inner cavity in the transition disk of TW Hydrae has been a subject of debate. Modeling the disk with data obtained at different wavelengths has led to a variety of proposed disk structures. Rather than being inconsistent, the individual models might point to the different faces of physical processes going on in disks, such as dust growth and planet formation.
Aims. Our aim is to investigate the structure of the transition disk again and to find to what extent we can reconcile apparent model differences.
Methods. A large set of high-angular-resolution data was collected from near-infrared to centimeter wavelengths. We investigated the existing disk models and established a new self-consistent radiative-transfer model. A genetic fitting algorithm was used to automatize the parameter fitting, and uncertainties were investigated in a Bayesian framework.
Results. Simple disk models with a vertical inner rim and a radially homogeneous dust composition from small to large grains cannot reproduce the combined data set. Two modifications are applied to this simple disk model: (1) the inner rim is smoothed by exponentially decreasing the surface density in the inner ~3 AU, and (2) the largest grains (>100 μm) are concentrated towards the inner disk region. Both properties can be linked to fundamental processes that determine the evolution of protoplanetary disks: the shaping by a possible companion and the different regimes of dust-grain growth, respectively.
Conclusions. The full interferometric data set from near-infrared to centimeter wavelengths requires a revision of existing models for the TW Hya disk. We present a new model that incorporates the characteristic structures of previous models but deviates in two key aspects: it does not have a sharp edge at 4 AU, and the surface density of large grains differs from that of smaller grains. This is the first successful radiative-transfer-based model for a full set of interferometric data.
Key words: protoplanetary disks / techniques: interferometric / stars: individual: TW Hya
© ESO, 2014
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