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Spectroastrometric imaging of molecular gas within protoplanetary disk gaps

Pontoppidan, Klaus M. and Blake, Geoffrey A. and van Dishoeck, Ewine F. and Smette, Alain and Ireland, Michael J. and Brown, Joanna (2008) Spectroastrometric imaging of molecular gas within protoplanetary disk gaps. Astrophysical Journal, 684 (2). pp. 1323-1329. ISSN 0004-637X.

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We present velocity-resolved spectroastrometric imaging of the 4.7 µm rovibrational lines of CO gas in protoplanetary disks using the CRIRES high-resolution infrared spectrometer on the Very Large Telescope (VLT). The method as applied to three disks with known dust gaps or inner holes out to 4-45 AU (SR 21, HD 135344B, and TW Hya) achieves an unprecedented spatial resolution of 0.1-0.5 AU. While one possible gap formation mechanism is dynamical clearing by giant planets, other equally good explanations (stellar companions, grain growth, photo-evaporation) exist. One way of distinguishing between different scenarios is the presence and distribution of gas inside the dust gaps. Keplerian disk models are fit to the spectroastrometric position-velocity curves to derive geometrical parameters of the molecular gas. We determine the position angles and inclinations of the inner disks with accuracies as good as 1°-2°, as well as the radial extent of the gas emission. Molecular gas is detected well inside the dust gaps in all three disks. The gas emission extends to within a radius of 0.5 AU for HD 135344B and to 0.1 AU for TW Hya, supporting partial clearing by a < 1-10 MJup planetary body as the cause of the observed dust gaps, or removal of the dust by extensive grain coagulation and planetesimal formation. The molecular gas emission in SR 21 appears to be truncated within ~7 AU, which may be caused by complete dynamical clearing by a more massive companion. We find a smaller inclination angle of the inner disk of TW Hya than that determined for the outer disk, suggestive of a disk warp. We also detect significant azimuthal asymmetries in the SR 21 and HD 135344B inner disks.

Item Type:Article
Related URLs:
URLURL TypeDescription
Pontoppidan, Klaus M.0000-0001-7552-1562
Blake, Geoffrey A.0000-0003-0787-1610
van Dishoeck, Ewine F.0000-0001-7591-1907
Ireland, Michael J.0000-0002-6194-043X
Additional Information:© 2008 The American Astronomical Society. Received 2008 January 26; accepted 2008 May 21. Support for K. M. P. was provided by NASA through Hubble Fellowship grant 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. G. A. B. acknowledges support from the NSF astronomy program. E. v. D. acknowledges a Netherlands Organization of Scientific Research (NWO) Spinoza Grant.
Funding AgencyGrant Number
NASA Hubble Fellowship01201.01
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Subject Keywords:ISM: molecules; planetary systems: protoplanetary disks; stars: individual (EM* SR 21, HD 135344B, TW Hya); techniques: high angular resolution
Issue or Number:2
Record Number:CaltechAUTHORS:PONapj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13339
Deposited By: Tony Diaz
Deposited On:13 Apr 2009 22:48
Last Modified:13 Dec 2019 04:13

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