Merín, Bruno and Brown, Joanna M. and Oliveira, Isa and Herczeg, Gregory J. and van Dishoeck , Ewine F. and Bottinelli, Sandrine and Evans, Neal J., II and Cieza, Lucas and Spezzi, Loredana and Alcalá, Juan M. and Harvey, Paul M. and Blake, Geoffrey A. and Bayo, Amelia and Geers, Vincent G. and Lahuis, Fred and Prusti, Timo and Augereau, Jean-Charles and Olofsson, Johan and Walter, Frederick M. and Chiu, Kuenley (2010) A Spitzer c2d Legacy Survey to Identify and Characterize Disks with Inner Dust Holes. Astrophysical Journal, 718 (2). pp. 1200-1223. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100806-153136126
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Understanding how disks dissipate is essential to studies of planet formation. However, identifying exactly how dust and gas dissipate is complicated due to the difficulty of finding objects that are clearly in the transition phase of losing their surrounding material.We use Spitzer Infrared Spectrograph (IRS) spectra to examine 35 photometrically selected candidate cold disks (disks with large inner dust holes). The infrared spectra are supplemented with optical spectra to determine stellar and accretion properties and 1.3 mm photometry to measure disk masses. Based on detailed spectral energy distribution modeling, we identify 15 new cold disks. The remaining 20 objects have IRS spectra that are consistent with disks without holes, disks that are observed close to edge-on, or stars with background emission. Based on these results, we determine reliable criteria to identify disks with inner holes from Spitzer photometry, and examine criteria already in the literature. Applying these criteria to the c2d surveyed starforming regions gives a frequency of such objects of at least 4% and most likely of order 12% of the young stellar object population identified by Spitzer.We also examine the properties of these new cold disks in combination with cold disks from the literature. Hole sizes in this sample are generally smaller than in previously discovered disks and reflect a distribution in better agreement with exoplanet orbit radii. We find correlations between hole size and both disk and stellar masses. Silicate features, including crystalline features, are present in the overwhelming majority of the sample, although the 10μm feature strength above the continuum declines for holes with radii larger than ~7 AU. In contrast, polycyclic aromatic hydrocarbons are only detected in 2 out of 15 sources. Only a quarter of the cold disk sample shows no signs of accretion, making it unlikely that photoevaporation is the dominant hole-forming process in most cases.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 December 31; accepted 2010 June 7; published 2010 July 13. Support for this work, part of the Spitzer Space Telescope Legacy Science Program, was provided by NASA through contract numbers 1224608 for c2d, 1288664 for GO3 IRS cold disks, 1256316 and 1230780 issued by the Jet Propulsion Laboratory, and for the California Institute of Technology under NASA contract 1407. Astrochemistry at Leiden was supported by a NWO Spinoza and NOVA grant, and by the European Research Training Network “The Origin of Planetary Systems” (PLANETS, contract number HPRN-CT-2002-00308). Facilities: Spitzer (IRAC, MIPS, IRS), CAO:2.2m (CAFOS), ING:Herschel (ISIS, WYFFOS), ING:Newton (IDS), PO:1.5m (DBSP), IRAM:30m (MAMBO)|
|Subject Keywords:||planetary systems; protoplanetary disks; stars: pre-main sequence|
|Classification Code:||PACS: 95.80.+p; 97.10.Gz; 97.21.+a|
|Official Citation:||Bruno Merín et al 2010 ApJ 718 1200 doi: 10.1088/0004-637X/718/2/1200|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||10 Aug 2010 23:42|
|Last Modified:||26 Dec 2012 12:17|
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