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Confronting Standard Models of Proto-planetary Disks with New Mid-infrared Sizes from the Keck Interferometer

Millan-Gabet, Rafael and Che, Xiao and Monnier, John D. and Sitko, Michael L. and Russell, Ray W. and Grady, Carol A. and Day, Amanda N. and Perry, R. B. and Harries, Tim J. and Aarnio, Alicia N. and Colavita, Mark M. and Wizinowich, Peter L. and Ragland, Sam and Woillez, Julien (2016) Confronting Standard Models of Proto-planetary Disks with New Mid-infrared Sizes from the Keck Interferometer. Astrophysical Journal, 826 (2). Art. No. 120. ISSN 0004-637X.

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We present near- and mid-infrared (MIR) interferometric observations made with the Keck Interferometer Nuller and near-contemporaneous spectro-photometry from the infrared telescope facilities (IRTFs) of 11 well-known young stellar objects, several of which were observed for the first time in these spectral and spatial resolution regimes. With au-level spatial resolution, we first establish characteristic sizes of the infrared emission using a simple geometrical model consisting of a hot inner rim and MIR disk emission. We find a high degree of correlation between the stellar luminosity and the MIR disk sizes after using near-infrared data to remove the contribution from the inner rim. We then use a semi-analytical physical model to also find that the very widely used "star + inner dust rim + flared disk" class of models strongly fails to reproduce the spectral energy distribution (SED) and spatially resolved MIR data simultaneously; specifically a more compact source of MIR emission is required than results from the standard flared disk model. We explore the viability of a modification to the model whereby a second dust rim containing smaller dust grains is added, and find that the 2-rim model leads to significantly improved fits in most cases. This complexity is largely missed when carrying out SED modeling alone, although detailed silicate feature fitting by McClure et al. recently came to a similar conclusion. As has been suggested recently by Menu et al., the difficulty in predicting MIR sizes from the SED alone might hint at "transition disk"-like gaps in the inner au; however, the relatively high correlation found in our MIR disk size versus stellar luminosity relation favors layered disk morphologies and points to missing disk model ingredients instead.

Item Type:Article
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URLURL TypeDescription Paper
Millan-Gabet, Rafael0000-0003-0447-5866
Monnier, John D.0000-0002-3380-3307
Sitko, Michael L.0000-0003-1799-1755
Harries, Tim J.0000-0001-8228-9503
Aarnio, Alicia N.0000-0002-1327-9659
Wizinowich, Peter L.0000-0002-1646-442X
Additional Information:© 2016 The American Astronomical Society. Received 2016 February 25; revised 2016 April 21; accepted 2016 April 21; published 2016 July 26. The authors acknowledge fruitful discussions with Nuria Calvet and Melissa McClure. Part of this work was performed while XC was a Visiting Graduate Student Research Fellow at the Infrared Processing and Analysis Center (IPAC), California Institute of Technology. The Keck Interferometer was funded by the National Aeronautics and Space Administration as part of its Exoplanet Exploration Program. Data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Data presented in this paper were obtained at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. We gratefully acknowledge support and participation in the IRTF/BASS observing runs by Daryl Kim, The Aerospace Corporation. This work has made use of services produced by the NASA Exoplanet Science Institute at the California Institute of Technology. M.S. was supported by NASA ADAP grant NNX09AC73G. R.W.R. was supported by the IR&D program of The Aerospace Corporation. Facilities: Keck: Interferometer - , IRTF. - Infrared Telescope Facility
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Aerospace CorporationUNSPECIFIED
Subject Keywords:infrared: stars – protoplanetary disks – stars: pre-main sequence – techniques: high angular resolution
Issue or Number:2
Record Number:CaltechAUTHORS:20160729-153531753
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Official Citation:Rafael Millan-Gabet et al 2016 ApJ 826 120
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69335
Deposited By: Tony Diaz
Deposited On:29 Jul 2016 22:52
Last Modified:09 Mar 2020 13:19

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