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VLT-CRIRES Survey of Rovibrational CO Emission from Protoplanetary Disks

Brown, J. M. and Pontoppidan, K. M. and van Dishoeck, E. F. and Herczeg, G. J. and Blake, G. A. and Smette, A. (2013) VLT-CRIRES Survey of Rovibrational CO Emission from Protoplanetary Disks. Astrophysical Journal, 770 (2). Art. No. 94. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20130724-135804503

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Abstract

We present a large, comprehensive survey of rovibrational CO line emission at 4.7 μm from 69 protoplanetary disks, obtained with CRIRES on the ESO Very Large Telescope at the highest available spectral resolving power (R = 95,000, Δv = 3.2 km s–1). The CO fundamental band (Δv = 1) is a well-known tracer of warm gas in the inner, planet-forming regions of gas-rich disks around young stars, with the lines formed in the super-heated surfaces of the disks at radii of 0.1-10 AU. Consistent with earlier studies, the presence of 100-1000 K CO is found to be ubiquitous around young stars which still retain disks. Our high spectral resolution data provide new insight into the kinematics of the inner disk gas. The observed line profiles are complex and reveal several different components. Pure double-peaked Keplerian profiles are surprisingly uncommon in our sample, beyond the frequency expected based on disk inclination. The majority of the profiles are consistent with emission from a disk plus a slow (few km s^(–1)) molecular disk wind. This is evidenced by analysis of different classes as well as an overall tendency for line profiles to have excess emission on their blue side. The data support the notion that thermal molecular winds are common for young disks. Thanks to the high spectral resolution, narrow absorption lines and weak emission lines from isotopologues and from vibrationally excited levels are readily detected. In general, ^(13)CO lines trace cooler gas than the bulk ^(12)CO emission and may arise from further out in the disk, as indicated by narrower line profiles. A high fraction of the sources show vibrationally excited emission (~50%) which is correlated with accretion luminosity, consistent with ultraviolet fluorescent excitation. Disks around early-type Herbig AeBe stars have narrower line profiles, on average, than their lower-mass late-type counterparts, due to their increased luminosity. Evolutionary changes in CO are also seen. Removal of the protostellar envelope between class I and II results in the disappearance of the strong absorption lines and CO ice feature characteristic of class I spectra. However, CO emission from class I and II objects are similar in detection frequency, excitation, and line shape, indicating that inner disk characteristics are established early.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/770/2/94DOIArticle
http://iopscience.iop.org/0004-637X/770/2/94PublisherArticle
http://arxiv.org/abs/1304.4961arXivDiscussion Paper
ORCID:
AuthorORCID
Pontoppidan, K. M.0000-0001-7552-1562
van Dishoeck, E. F.0000-0001-7591-1907
Herczeg, G. J.0000-0002-7154-6065
Blake, G. A.0000-0003-0787-1610
Additional Information:© 2013 American Astronomical Society. Received 2012 October 4; accepted 2013 April 15; published 2013 May 29. The authors thank Colette Salyk, Jeanette Bast, Wing-Fai Thi, Bill Dent, and Kevin France for discussions and contributions to the program. We also thank the anonymous referee for comments which improved this paper. This work is based on observations collected at the European Southern Observatory Very Large Telescope under program ID 179.C-0151. J.M.B. acknowledges the Smithsonian Astrophysical Observatory for support from a SMA fellowship. 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. Astrochemistry at Leiden is supported by a Spinoza grant from the Netherlands Organization for Scientific Research (NWO), by NWO grant 614.000.605, and by the Netherlands Research School for Astronomy (NOVA).
Funders:
Funding AgencyGrant Number
Smithsonian Astrophysical ObservatoryUNSPECIFIED
NASA Hubble Fellowship01201.01
NASANAS 5-26555
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)614.000.605
Nederlandse Onderzoekschool voor de Astronomie (NOVA)UNSPECIFIED
Subject Keywords:infrared: general; protoplanetary disks; stars: formation; stars: pre-main sequence; stars: protostars
Record Number:CaltechAUTHORS:20130724-135804503
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130724-135804503
Official Citation:VLT-CRIRES Survey of Rovibrational CO Emission from Protoplanetary Disks VLT-CRIRES Survey of Rovibrational CO Emission from Protoplanetary Disks J. M. Brown, K. M. Pontoppidan, E. F. van Dishoeck, G. J. Herczeg, G. A. Blake, and A. Smette doi:10.1088/0004-637X/770/2/94
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39561
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:24 Jul 2013 21:21
Last Modified:28 Oct 2017 01:26

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