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Published October 10, 1995 | Published
Journal Article Open

Aperture Synthesis Imaging of the Circumstellar Dust Disk around DO Tauri

Abstract

We have detected the T Tauri star, DO Tauri, in a 0 6 resolution VLA map of 43.3 GHz (λ = 7 mm) continuum emission. The 43 GHz flux density lies on the same power-law slope defined by 89-232 GHz measurements, F_ν ∝ ν^α with index α = 2.39 ± 0.23, confirming that the 43.3 GHz emission is thermal radiation from circumstellar dust. Upper limits to the flux densities at 8.4 and 22.5 GHz constrain the contribution of free-free emission from a compact ionized wind to be less than 49%. The dust emissivity index, β, is 0.39 ± 0.23 if the emission is optically thin. Fitting a model of a thin circumstellar disk to the observed spectral energy distribution gives β = 0.6 ± 0.3, consistent with the power-law derivation. Both values are substantially lower than is generally accepted for the interstellar medium, suggesting grain growth. Given the youth of DO Tau and the early evolutionary state of its circumstellar disk, this result implies that millimeter-size grains have already formed by the early T Tauri phase.

Additional Information

© 1995 The American Astronomical Society. Received 1995 June 8; accepted 1995 August 1. We are grateful to D. Wood for assistance during the first season of 43 GHz observations at the VLA. D. W. K. acknowledges support for this work from NASA grant NGT-51071 and a fellowship from the National Research Council. The Owens Valley millimeter-wave array is supported by NSF grant AST-9314079. Research by A. I. S. on protoplanetary disks is furthered by NASA grant NAGW-4030 from the ''Origins of Solar Systems'' program. The research described in this paper was carried out by the Jet Propulsion Laboratory and the California Institute of Technology and was sponsored by a fellowship from the National Research Council and the National Aeronautics and Space Administration.

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