Chemical evolution of protoplanetary disks - the effects of viscous accretion, turbulent mixing and disk winds

D. Heinzeller, H. Nomura, Catherine Walsh, TJ Millar

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Abstract

We calculate the chemical evolution of protoplanetary disks considering radial viscous accretion, vertical turbulent mixing, and vertical disk winds. We study the effects on the disk chemical structure when different models for the formation of molecular hydrogen on dust grains are adopted. Our gas-phase chemistry is extracted from the UMIST Database for Astrochemistry (Rate06) to which we have added detailed gas-grain interactions. We use our chemical model results to generate synthetic near- and mid-infrared local thermodynamic equilibrium line emission spectra and compare these with recent Spitzer observations. Our results show that if H2 formation on warm grains is taken into consideration, the H2O and OH abundances in the disk surface increase significantly. We find that the radial accretion flow strongly influences the molecular abundances, with those in the cold midplane layers particularly affected. On the other hand, we show that diffusive turbulent mixing affects the disk chemistry in the warm molecular layers, influencing the line emission from the disk and subsequently improving agreement with observations. We find that NH3, CH3OH, C2H2, and sulfur-containing species are greatly enhanced by the inclusion of turbulent mixing. We demonstrate that disk winds potentially affect the disk chemistry and the resulting molecular line emission in a manner similar to that found when mixing is included.
Original languageEnglish
Article number115
Number of pages22
JournalAstrophysical Journal
Volume731
Issue number2
Early online date31 Mar 2011
DOIs
Publication statusPublished - 20 Apr 2011

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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