Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 2S029

Molecular imprint of dust evolution

Akimkin, Vitaly (Institute of Astronomy of the RAS, Russia)
Zhukovska, Svitlana (Max Planck Institute for Astronomy, Germany)
Wiebe, Dmitri (Institute of Astronomy of the RAS, Russia)
Semenov, Dmitry (Max Planck Institute for Astronomy, Germany)
Pavlyuchenkov, Yaroslav (Institute of Astronomy of the RAS, Russia)
Vasyunin, Anton (University of Virginia, USA)
Birnstiel, Til (Harvard-Smithsonian Center for Astrophysics, USA)
Henning, Thomas (Max Planck Institute for Astronomy, Germany)

Evolution of sub-micron grains is an essential process during early stages of planet formation. The dust growth and sedimentation to the midplane affect a spectral energy distribution. At the same time dust evolution can alter significantly the distribution of gas that is a factor of 100 more massive than dust and can be traced with molecular line observations. We present simulations of protoplanetary disk structure with grain evolution using the ANDES code (\"AccretioN disk with Dust Evolution and Sedimentation\"). ANDES comprises (1) a 1+1D frequency-dependent continuum radiative transfer module, (2) a module to calculate the chemical evolution using an extended gas–grain chemical network with UV/X-ray-driven processes and surface reactions, (3) a module to calculate the gas thermal energy balance, and (4) a 1+1D module that simulates dust grain evolution. Such a set of physical processes allows us to assess the impact of dust evolution on the gas component, which is primarily related to radiation field and total available surface for chemical reactions. Considering cases of (i) evolved dust (2 Myr of grain coagulation, fragmentation and sedimentation) and (ii) pristine dust (well- mixed 0.1 micron grains), we found a sufficient changes in disk physical and chemical structure caused by the dust evolution. Due to higher transparency of the evolved disk model UV-shielded molecular layer is shifted closer to the midplane. The presence of big grains in the disk midplane delays the freeze-out of volatile gas-phase species such as CO, while the depletion is still effective in adjacent upper layers. Molecular concentrations of many species are enhanced in the disk model with dust evolution (CO2, NH2CN, HNO, H2O, HCOOH, HCN, CO) which provides an opportunity to use these molecules as tracers of dust evolution.

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