The Gas Disk: Evolution and Chemistry

Rab, Ch.; Baldovin-Saavedra, C.; Dionatos, O.; Vorobyov, Eduard I.; Güdel, M.

doi:10.1007/s11214-016-0325-5

Cited by 5 publications

(1 citation statement)

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“…Mass is transported through the disk onto the star, and the gas and dust in the disk is available for planet formation. Emission lines from disk atmospheres offer clues to the dynamical state of the gas (e.g., probing disk rotation, turbulent line broadening), its chemical transformation (e.g., synthesis of organic molecules), and the processes that determine the thermal properties of the atmosphere (Rab et al 2016;Carmona 2010;Najita et al 2007. ) The thermal structure of the disk affects both its chemistry and observational signatures.…”

Section: Introductionmentioning

confidence: 99%

FUV Irradiation and the Heat Signature of Accretion in Protoplanetary Disk Atmospheres

Najita

Ádámkovics

2017

ApJ

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Although stars accrete mass throughout the first few Myr of their lives, the physical mechanism that drives disk accretion in the T Tauri phase is uncertain, and diagnostics that probe the nature of disk accretion have been elusive, particularly in the planet formation region of the disk. Here we explore whether an accretion process such as the magnetorotational instability could be detected through its "heat signature", the energy it deposits in the disk atmosphere. To examine this possibility, we investigate the impact of accretion-related mechanical heating and energetic stellar irradiation (FUV and X-rays) on the thermal-chemical properties of disk atmospheres at planet formation distances. We find that stellar FUV irradiation (Lyα and continuum), through its role in heating and photodissociation, affects much of the upper warm (400-2000 K) molecular layer of the atmosphere, and the properties of the layer are generally in good agreement with the observed molecular emission features of disks at UV, near-infrared, and midinfrared wavelengths. At the same time, the effect of FUV irradiation is restricted to the upper molecular layer of the disk, even when irradiation by Lyα is included. The region immediately below the FUV-heated layer is potentially dominated by accretion-related mechanical heating. As cooler (90-400 K) CO, water, and other molecules are potential diagnostics of the mechanically-heated layer, emission line studies of these diagnostics might be used to search for evidence of the magnetorotational instability in action.

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Section: Introductionmentioning

confidence: 99%