Cold Disks: Spitzer Spectroscopy of Disks around Young Stars with Large Gaps
Abstract
We have identified four circumstellar disks with a deficit of dust emission from their inner 15-50 AU. All four stars have F-G spectral type and were uncovered as part of the Spitzer Space Telescope "Cores to Disks" Legacy Program Infrared Spectrograph (IRS) first-look survey of ~100 pre-main-sequence stars. Modeling of the spectral energy distributions indicates a reduction in dust density by factors of 100-1000 from disk radii between ~0.4 and 15-50 AU but with massive gas-rich disks at larger radii. This large contrast between the inner and outer disk has led us to use the term "cold disks" to distinguish these unusual systems. However, hot dust [(0.02-0.2)M_(moon)] is still present close to the central star (R ≤ 0.8 AU). We introduce the 30 μm/13 μm flux density ratio as a new diagnostic for identifying cold disks. The mechanisms for dust clearing over such large gaps are discussed. Although rare, cold disks are likely in transition from an optically thick to an optically thin state and so offer excellent laboratories for the study of planet formation.
Additional Information
© 2007 The American Astronomical Society. Received 2006 December 1; accepted 2007 June 12; published 2007 July 17. Support for this work, part of the Spitzer Legacy Science Program, was provided by NASA through contracts 1224608, 1230779, and 1256316 issued by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Astrochemistry in Leiden is supported by a NWO Spinoza grant and a NOVA grant, and by the EU RTN-PLANETS (HPRN-CT-2002-00308). B. M. acknowledges the financial support from the Fundacion Ramon Areces (Spain). We thank the Lorentz Center in Leiden for hosting several meetings that contributed to this Letter.Attached Files
Published - BROapjl07.pdf
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Additional details
- Eprint ID
- 16495
- Resolver ID
- CaltechAUTHORS:20091027-130736915
- 1224608
- NASA
- 1230779
- NASA
- 1256316
- NASA
- 1407
- NASA
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
- Nederlandse Onderzoekschool voor de Astronomie (NOVA)
- HPRN-CT-2002-00308
- European Research Training Network
- Fundacion Ramon Areces
- Created
-
2009-10-30Created from EPrint's datestamp field
- Updated
-
2021-11-08Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences