Modeling the gas-phase chemistry of the transitional disk around HD 141569A

摘要: Aims. The chemistry, distribution and mass of the gas in transitional disk around 5 Myr old B9.5 V star HD 141569A are constrained. Methods. A quasi 2-dimensional (2D) chemistry code for photon dominated regions (PDR) is used to calculate temperatures disk. calculations performed several distributions, PAH abundances values total mass. resulting CO $J=2{-}1$ $J=3{-}2$ emission lines computed with a 2D radiative transfer compared observations. Results. CO abundance very sensitive because a regime where self-shielding just sets in. observed CO emission best fit by a power-law of $80~M_\oplus$ starting at 80 AU from central star, indicating that there some inner hole. Predictions made intensities atomic fine-structure lines. [$\ion{C}{i}$], which dominant form carbon large parts disk, found be a good alternative tracer