Free access article

A&A 446, 211-221 (2006)
DOI: 10.1051/0004-6361:20054038

Large dust particles in disks around T Tauri stars

J. Rodmann¹, Th. Henning¹, C. J. Chandler², L. G. Mundy³ and D. J. Wilner<sup>4

1</sup>  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117, Heidelberg, Germany
    e-mail: rodmann@mpia.de
²  National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA
³  Department of Astronomy, University of Maryland, College Park, MD 20742, USA
⁴  Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

(Received 12 August 2005 / Accepted 14 September 2005 )

Abstract
We present 7-mm continuum observations of 14 low-mass pre-main-sequence stars in the Taurus-Auriga star-forming region obtained with the Very Large Array with ~1 5 resolution and ~0.3 mJy rms sensitivity. For 10 objects, the circumstellar emission has been spatially resolved. The large outer disk radii derived suggest that the emission at this wavelength is mostly optically thin. The millimetre spectral energy distributions are characterised by spectral indices  2.3 to 3.2. After accounting for contributions from free-free emission and corrections for optical depth, we determine dust opacity indices in the range 0.5 to 1.6, which suggest that millimetre-sized dust aggregates are present in the circumstellar disks. Four of the sources with may be consistent with submicron-sized dust as found in the interstellar medium. Our findings indicate that dust grain growth to millimetre-sized particles is completed within less than 1 Myr for the majority of circumstellar disks.

Key words: stars: pre-main sequence -- stars: planetary systems: protoplanetary disks -- planetary systems: formation

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© ESO 2006

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