PROTOPLANETARY DISK STRUCTURE WITH GRAIN EVOLUTION: THE ANDES MODEL

Journal Article · Wed Mar 20 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/766/1/8· OSTI ID:22167594

Akimkin, V.; Wiebe, D.; Pavlyuchenkov, Ya. ^[1]; Zhukovska, S.; Semenov, D.; Henning, Th. ^[2]; Vasyunin, A. ^[3]

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1. Institute of Astronomy of the RAS, Pyatnitskaya str. 48, Moscow (Russian Federation)
2. Max-Planck-Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)
3. Department of Chemistry, The University of Virginia, VA (United States)

We present a self-consistent model of a protoplanetary disk: 'ANDES' ('AccretioN disk with Dust Evolution and Sedimentation'). ANDES is based on a flexible and extendable modular structure that includes (1) a 1+1D frequency-dependent continuum radiative transfer module, (2) a module to calculate the chemical evolution using an extended gas-grain 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. For the first time, grain evolution and time-dependent molecular chemistry are included in a protoplanetary disk model. We find that grain growth and sedimentation of large grains onto the disk midplane lead to a dust-depleted atmosphere. Consequently, dust and gas temperatures become higher in the inner disk (R {approx}< 50 AU) and lower in the outer disk (R {approx}> 50 AU), in comparison with the disk model with pristine dust. The response of disk chemical structure to the dust growth and sedimentation is twofold. First, due to higher transparency a partly UV-shielded molecular layer is shifted closer to the dense midplane. Second, the presence of big grains in the disk midplane delays the freeze-out of volatile gas-phase species such as CO there, while in adjacent upper layers the depletion is still effective. Molecular concentrations and thus column densities of many species are enhanced in the disk model with dust evolution, e.g., CO{sub 2}, NH{sub 2}CN, HNO, H{sub 2}O, HCOOH, HCN, and CO. We also show that time-dependent chemistry is important for a proper description of gas thermal balance.

• OSTI ID: 22167594
• Journal Information: Astrophysical Journal, Vol. 766, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
CARBON DIOXIDE
CARBON MONOXIDE
CONCENTRATION RATIO
COSMIC DUST
DENSITY
FREEZING OUT
FREQUENCY DEPENDENCE
GALACTIC EVOLUTION
GRAIN GROWTH
HYDROCYANIC ACID
MODULAR STRUCTURES
PROTOPLANETS
RADIANT HEAT TRANSFER
SURFACES
TIME DEPENDENCE
ULTRAVIOLET RADIATION
VOLATILITY
WATER
X RADIATION