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The Structure and Dynamics of Molecular Gas in Planet-forming Zones: A CRIRES Spectro-astrometric Survey

Pontoppidan, Klaus M. and Blake, Geoffrey A. and Smette, Alain (2011) The Structure and Dynamics of Molecular Gas in Planet-forming Zones: A CRIRES Spectro-astrometric Survey. Astrophysical Journal, 733 (2). Art. No. 84. ISSN 0004-637X.

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We present a spectro-astrometric survey of molecular gas in the inner regions of 16 protoplanetary disks using CRIRES, the high-resolution infrared imaging spectrometer on the Very Large Telescope. Spectro-astrometry with CRIRES measures the spatial extent of line emission to sub-milliarcsecond precision, or <0.2 AU at the distance of the observed targets. The sample consists of gas-rich disks surrounding stars with spectral types ranging from K to A. The properties of the spectro-astrometric signals divide the sources into two distinct phenomenological classes: one that shows clear Keplerian astrometric spectra and one in which the astrometric signatures are dominated by gas with strong non-Keplerian (radial) motions. Similarly to the near-infrared continuum emission, as determined by interferometry, we find that the size of the CO line emitting region in the Keplerian sources obeys a size-luminosity relation as R_(CO) α_L^(0.5)_*. The non-Keplerian spectro-astrometric signatures are likely indicative of the presence of wide-angle disk winds. The central feature of the winds is a strong sub-Keplerian velocity field due to conservation of angular momentum as the wind pressure drives the gas outward. We construct a parameterized two-dimensional disk+wind model that reproduces the observed characteristics of the observed CO spectra and astrometry. The modeled winds indicate mass-loss rates of ≳ 10^(–10) to 10^(–8) M_⊙ yr^(–1). We suggest a unifying model in which all disks have slow molecular winds, but where the magnitude of the mass-loss rate determines the degree to which the mid-infrared molecular lines are dominated by the wind relative to the Keplerian disk surface.

Item Type:Article
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URLURL TypeDescription
Pontoppidan, Klaus M.0000-0001-7552-1562
Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2011 The American Astronomical Society. Received 2010 October 12; accepted 2011 March 14; published 2011 May 9. The authors are grateful to Colette Salyk and Ewine van Dishoeck for comments that improved the manuscript. Joanna Brown and Bill Dent are thanked for obtaining some of our spectro-astrometric data. A very special thanks goes out to all the Paranal personnel that assisted with our visitor observations, without whom this study would not have been possible. Support for K.M.P. was provided by NASA through Hubble Fellowship grant No. 01201.01 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. This paper is based on observations made with ESO Telescopes at the Paranal Observatory under program ID 179.C-0151.
Funding AgencyGrant Number
NASA Hubble Fellowship01201.01
Subject Keywords:ISM: molecules; line: profiles; protoplanetary disks; techniques: imaging spectroscopy
Issue or Number:2
Classification Code:PACS: 95.80.+p; 98.38.Bn; 95.85.Kr; 97.21+a; 97.20.Jg; 97.82.Jw
Record Number:CaltechAUTHORS:20110607-091154196
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Official Citation:The Structure and Dynamics of Molecular Gas in Planet-forming Zones: A CRIRES Spectro-astrometric Survey Klaus M. Pontoppidan, Geoffrey A. Blake and Alain Smette doi: 10.1088/0004-637X/733/2/84
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23923
Deposited By: Ruth Sustaita
Deposited On:07 Jun 2011 16:34
Last Modified:03 Oct 2019 02:51

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