Oliveira, Isa and Pontoppidan, Klaus M. and Merín, Bruno and van Dishoeck, Ewine F. and Lahuis, Fred and Geers, Vincent C. and Jørgensen, Jes K. and Olofsson, Johan and Augereau, Jean-Charles and Brown, Joanna M. (2010) A Spitzer Survey of Protoplanetary Disk Dust in the Young Serpens Cloud: How do Dust Characteristics Evolve with Time? Astrophysical Journal, 714 (1). pp. 778-798. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100604-101211287
- Published Version
See Usage Policy.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20100604-101211287
We present Spitzer InfraRed Spectrograph (IRS) mid-infrared (5-35 μm) spectra of a complete flux-limited sample (≥3 mJy at 8 μm) of young stellar object (YSO) candidates selected on the basis of their infrared colors in the Serpens Molecular Cloud. Spectra of 147 sources are presented and classified. Background stars (with slope consistent with a reddened stellar spectrum and silicate features in absorption), galaxies (with redshifted polycyclic aromatic hydrocarbon (PAH) features), and a planetary nebula (with high ionization lines) amount to 22% of contamination in this sample, leaving 115 true YSOs. Sources with rising spectra and ice absorption features, classified as embedded Stage I protostars, amount to 18% of the sample. The remaining 82% (94) of the disk sources are analyzed in terms of spectral energy distribution shapes, PAHs, and silicate features. The presence, strength, and shape of these silicate features are used to infer disk properties for these systems. About 8% of the disks have 30/13 μm flux ratios consistent with cold disks with inner holes or gaps, and 3% of the disks show PAH emission. Comparison with models indicates that dust grains in the surface of these disks have sizes of at least a few μm. The 20 μm silicate feature is sometimes seen in the absence of the 10 μm feature, which may be indicative of very small holes in these disks. No significant difference is found in the distribution of silicate feature shapes and strengths between sources in clusters and in the field. Moreover, the results in Serpens are compared with other well-studied samples: the c2d IRS sample distributed over five clouds and a large sample of disks in the Taurus star-forming region. The remarkably similar distributions of silicate feature characteristics in samples with different environment and median ages—if significant—imply that the dust population in the disk surface results from an equilibrium between dust growth and destructive collision processes that are maintained over a few million years for any YSO population irrespective of environment.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 December 28; accepted 2010 March 16; published 2010 April 14. Legacy Science Program, was provided by NASA through Contract Numbers 1256316, 1224608, and 1230780 issued by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407 and by the Spanish Grant AYA 2005-0954. Astrochemistry at Leiden is supported by a Spinoza grant from the Netherlands Organization for Scientific Research (NWO) and by the Netherlands Research School for Astronomy (NOVA) grants. Support to 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. The authors are very grateful to L. Allamandola, R. Overzier, P. Beirao, R. Demarco, J. Green, and A. K´ospal for fruitful discussions, and would like to acknowledge the anonymous referee for suggestions that have improved the manuscript considerably. Facilities: Spitzer(IRS)|
|Subject Keywords:||circumstellar matter; infrared: stars; planetary systems; protoplanetary disks; stars: pre-main sequence|
|Classification Code:||PACS: 97.21.+a; 98.62.Lv; 98.58.Li; 98.58.Bz; 95.30.Ky; 98.58.Db.|
|Official Citation:||Isa Oliveira et al 2010 ApJ 714 778 doi: 10.1088/0004-637X/714/1/778|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||27 Jun 2010 23:38|
|Last Modified:||26 Dec 2012 12:06|
Repository Staff Only: item control page