Diagnostic value of far-IR water ice features in T Tauri disks

Abstract

This paper investigates how the far-IR water ice features can be used to infer properties of disks around T Tauri stars and the water ice thermal history. We explore the power of future observations with SOFIA/HIRMES and SPICA's proposed far-IR instrument SAFARI. A series of detailed radiative transfer disk models around a representative T Tauri star are used to investigate how the far-IR water ice features at 45 and 63 micron change with key disk properties: disk size, grain sizes, disk dust mass, dust settling, and ice thickness. In addition, a series of models is devised to calculate the water ice emission features from warmup, direct deposit and cooldown scenarios of the water ice in disks. Photodesorption from icy grains in disk surfaces weakens the mid-IR water ice features by factors 4-5. The far-IR water ice emission features originate from small grains at the surface snow line in disks at distance of 10-100 au. Unless this reservoir is missing in disks (e.g. transitional disks with large cavities), the feature strength is not changing. Grains larger than 10 micron do not contribute to the features. Grain settling (using turbulent description) is affecting the strength of the ice features by at most 15%. The strength of the ice feature scales with the disk dust mass and water ice fraction on the grains, but saturates for dust masses larger than 1.e-4 Msun and for ice mantles that increase the dust mass by more than 50%. The various thermal histories of water ice leave an imprint on the shape of the features (crystalline/amorphous) as well as on the peak strength and position of the 45 micron feature. SOFIA/HIRMES can only detect crystalline ice features much stronger than simulated in our standard T Tauri disk model in deep exposures (1 hr). SPICA/SAFARI can detect the typical ice features in our standard T Tauri disk model in short exposures (10 min). (abbreviated)

arXiv commentaccepted for publication in A&A

References in corpus (16)

• The photodissociation and chemistry of CO isotopologues: applications to interstellar clouds and circumstellar disks
• A Steeper than Linear Disk Mass-Stellar Mass Scaling Relation
• Consistent dust and gas models for protoplanetary disks. I. Disk shape, dust settling, opacities, and PAHs
• The stickiness of micrometer-sized water-ice particles
• Detection of the Water Reservoir in a Forming Planetary System
• Spectral Energy Distributions of T Tauri and Herbig Ae Disks: Grain Mineralogy, Parameter Dependences, and Comparison with ISO LWS Observations
• Radiative transfer in very optically thick circumstellar disks
• Multiwavelength optical properties of compact dust aggregates in protoplanetary disks
• Dust Evolution Can Produce Scattered Light Gaps in Protoplanetary Disks
• Water vapor in the protoplanetary disk of DG Tau
• Gas phase water in the surface layer of protoplanetary disks
• Hot and cool water in Herbig Ae protoplanetary disks. A challenge for Herschel
• Detections of trans-Neptunian ice in protoplanetary disks
• The abundance and thermal history of water ice in the disk surrounding HD142527 from the DIGIT Herschel Key Program
• Probing dynamical processes in the planet forming region with dust mineralogy
• Accretion in Protoplanetary Disks by Collisional Fusion

Cited by in corpus (7)

• Astrochemistry and compositions of planetary systems
• Simulating Observations of Ices 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?
• Constraining the detectability of water ice in debris disks
• Solar wind charge exchange in cometary atmospheres. II. Analytical model
• Ices in planet-forming disks: Self-consistent ice opacities in disk models
• Impact of ice growth on the physical and chemical properties of dense cloud cores