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Title: DETECTIONS OF TRANS-NEPTUNIAN ICE IN PROTOPLANETARY DISKS

We present Herschel Space Observatory PACS spectra of T Tauri stars, in which we detect amorphous and crystalline water ice features. Using irradiated accretion disk models, we determine the disk structure and ice abundance in each of the systems. Combining a model-independent comparison of the ice feature strength and disk size with a detailed analysis of the model ice location, we estimate that the ice emitting region is at disk radii >30 AU, consistent with a proto-Kuiper belt. Vertically, the ice emits most below the photodesorption zone, consistent with Herschel observations of cold water vapor. The presence of crystallized water ice at a disk location (1) colder than its crystallization temperature and (2) where it should have been re-amorphized in ∼1 Myr suggests that localized generation is occurring; the most likely cause appears to be micrometeorite impact or planetesimal collisions. Based on simple tests with UV models and different ice distributions, we suggest that the SED shape from 20 to 50 μm may probe the location of the water ice snowline in the disk upper layers. This project represents one of the first extra-solar probes of the spatial structure of the cometary ice reservoir thought to deliver water to terrestrial planets.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Bldg., Ann Arbor, MI 48109 (United States)
  2. Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)
  3. Centro de Radioastronomía y Astrofísica, Universidad NacionalAUtónoma de México, 58089 Morelia, Michoacán (Mexico)
  4. Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)
  5. Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)
  6. Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)
Publication Date:
OSTI Identifier:
22364367
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; COMPARATIVE EVALUATIONS; CRYSTALLIZATION; DETECTION; ICE; IRRADIATION; METEORITES; PHOTON EMISSION; PLANETS; PROBES; PROTOPLANETS; RADIANT HEAT TRANSFER; SPACE; T TAURI STARS; WATER; WATER VAPOR