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Millimetre spectral indices of transition disks and their relation to the cavity radius

Pinilla, P. and Benisty, M. and Birnstiel, T. and Ricci, L. and Isella, A. and Natta, A. and Dullemond, C. P. and Quiroga-Nuñez, L. H. and Henning, T. and Testi, L. (2014) Millimetre spectral indices of transition disks and their relation to the cavity radius. Astronomy and Astrophysics, 564 . Art. No. A51. ISSN 0004-6361.

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Context. Transition disks are protoplanetary disks with inner depleted dust cavities that are excellent candidates for investigating the dust evolution when there is a pressure bump. A pressure bump at the outer edge of the cavity allows dust grains from the outer regions to stop their rapid inward migration towards the star and to efficiently grow to millimetre sizes. Dynamical interactions with planet(s) have been one of the most exciting theories to explain the clearing of the inner disk. Aims. We look for evidence of millimetre dust particles in transition disks by measuring their spectral index α_mm with new and available photometric data. We investigate the influence of the size of the dust depleted cavity on the disk integrated millimetre spectral index. Methods. We present the 3-mm (100 GHz) photometric observations carried out with the Plateau de Bure Interferometer of four transition disks: LkHα 330, UX Tau A, LRLL 31, and LRLL 67. We used the available values of their fluxes at 345 GHz to calculate their spectral index, as well as the spectral index for a sample of twenty transition disks. We compared the observations with two kinds of models. In the first set of models, we considered coagulation and fragmentation of dust in a disk in which a cavity is formed by a massive planet located at different positions. The second set of models assumes disks with truncated inner parts at different radii and with power-law dust-size distributions, where the maximum size of grains is calculated considering turbulence as the source of destructive collisions. Results. We show that the integrated spectral index is higher for transition disks (TD) than for regular protoplanetary disks (PD) with mean values of α^(TD)_(mm) = 2.70 ± 0.13 and α^(PD)_(mm) = 2.20 ± 0.07 respectively. For transition disks, the probability that the measured spectral index is positively correlated with the cavity radius is 95%. High angular resolution imaging of transition disks is needed to distinguish between the dust trapping scenario and the truncated disk case.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pinilla, P.0000-0001-8764-1780
Benisty, M.0000-0002-7695-7605
Isella, A.0000-0001-8061-2207
Testi, L.0000-0003-1859-3070
Additional Information:© 2014 ESO. Article published by EDP Sciences. Received 23 December 2013; accepted 24 February 2014. Published online 03 April 2014. The authors are very thankful to J. M. Winters for his help understanding GILDAS for the PdBI data reduction. We acknowledge S. Andrews, N. van der Marel, and E. van Dishoeck for the helpful comments and feedback on the manuscript. TB acknowledges support from NASA Origins of Solar Systems grant NNX12AJ04G. This publication is based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:accretion, accretion disks; protoplanetary disks; circumstellar matter; planets and satellites: formation
Record Number:CaltechAUTHORS:20140529-084912046
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Official Citation:Millimetre spectral indices of transition disks and their relation to the cavity radius P. Pinilla, M. Benisty, T. Birnstiel, L. Ricci, A. Isella, A. Natta, C. P. Dullemond, L. H. Quiroga-Nuñez, T. Henning and L. Testi A&A 564 A51 (2014) DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45960
Deposited By: Jason Perez
Deposited On:29 May 2014 18:24
Last Modified:09 Mar 2020 13:18

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