Detections of trans-Neptunian ice in protoplanetary disks

Abstract

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 >30AU, 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 a) colder than its crystallization temperature and b) 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 micron may probe the location of the water ice snow line 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.

Accepted to ApJ on Nov. 20th 2014; 16 pages, including 11 figures and 4 tables

References in corpus (4)

• The chemical history of molecules in circumstellar disks. I. Ices
• The Disk Population of the Chamaeleon I Star-Forming Region
• Crystalline silicates and dust processing in the protoplanetary disks of the Taurus young cluster
• Near-Infrared Interferometric, Spectroscopic, and Photometric Monitoring of T Tauri Inner Disks

Cited by in corpus (19)

• Astrochemistry and compositions of planetary systems
• Mass measurements in protoplanetary disks from hydrogen deuteride
• Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
• The Evolution of Disk Winds from a Combined Study of Optical and Infrared Forbidden Lines
• Carbon depletion observed inside T Tauri inner rims: Formation of icy, kilometer size planetesimals by 1 Myr
• Laboratory and Computational Studies of Interstellar Ices
• The abundance and thermal history of water ice in the disk surrounding HD142527 from the DIGIT Herschel Key Program
• Dust continuum emission and the upper limit fluxes of sub-millimeter water lines of the protoplanetary disk around HD 163296 observed by ALMA
• Simulating Observations of Ices in Protoplanetary Disks
• Influence of the ice structure on the soft UV photochemistry of PAHs embedded in solid water
• The nitrogen carrier in protoplanetary disks
• The water-ice feature in near-infrared disk-scattered light around HD 142527: Micron-sized icy grains lifted up to the disk surface?
• Detection of Near-Infrared Water Ice at the Surface of the (pre)Transitional Disk of AB Aur: Informing Icy Grain Abundance, Composition, and Size
• Thermal Behavior of Astrophysical Amorphous Molecular Ices
• Vacuum ultraviolet photodesorption and photofragmentation of formaldehyde-containing ices
• Ices in planet-forming disks: Self-consistent ice opacities in disk models
• Disk evolution and the fate of water
• Protoplanetary Disk Science with the Orbiting Astronomical Satellite Investigating Stellar Systems (OASIS) Observatory
• The formation of planetary systems with SPICA