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Coordinated Hydrodynamic and Astrophysical Research, Modeling, and Synthesis (CHARMS)

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A hydrochemical hybrid code (KM2) and its benchmarks for a Photon-Dominated Region (PDR)

Image Credit: Motoyama, Morata, Shang, Krasnopolsky, and Hasegawa

Chemical abundances at the time t = 1 Myr (top) and t = 3 Myr (bottom) as a function of z-coordinates (left) and of visual extinction (right) in our hydrochemical simulation. The solid and dashed lines represent results for PDR benchmark model V2 and for the reference model with a larger chemical network, respectively.

A two-dimensional hydro-chemical hybrid code, KM2, is constructed to deal with astrophysical problems that would require coupled hydrodynamical and chemical evolution. The code assumes axisymmetry in the cylindrical coordinate system and consists of two modules: a hydrodynamics module and a chemistry module. The hydrodynamics module solves hydrodynamics using a Godunov-type finite volume scheme and treats included chemical species as passively advected scalars. The chemistry module implicitly solves non-equilibrium chemistry and change of the energy due to thermal processes with the transfer of external ultraviolet radiation. Self-shielding effects on photodissociation of CO and H₂ are included.