标题： 具有应用到 circumstellar 盘化学的紫外辐射传输的轴对称模型 显示英文标题

标题： Axi-symmetric models of ultraviolet radiative transfer with applications to circumstellar disk chemistry

摘要： 提出了一种新的二维轴对称紫外辐射传递代码，用于计算耀发星周盘化学模型中的光解离和电离率。考虑了来自中心恒星以及星际辐射场的光子的散射和吸收。分子在盘表面层被有效光解离，但在中间适度温暖的层中可以存在。与一种近似的二维光线追踪方法进行了比较，发现后者低估了盘面下的紫外场强及分子光解离率。完整的二维结果表明，自由基（如CN和C2H）的丰度显著高于之前的研究，部分原因是由于CO在更深的深度被解离。还展示了不同恒星辐射场的结果。CN/HCN比值对恒星光谱表现出强烈的依赖性，而其他比值（如HCO+/CO）则显示出较小的变化。 显示英文摘要

摘要： A new two-dimensional axi-symmetric ultraviolet radiative transfer code is presented, which is used to calculate photodissociation and ionization rates for use in chemistry models of flaring circumstellar disks. Scattering and absorption of photons from the central star and from the interstellar radiation field are taken into account. The molecules are effectively photodissociated in the surface layer of the disk, but can exist in the intermediate, moderately warm layers. A comparison has been made with an approximate 2D ray-tracing method and it was found that the latter underestimates the ultraviolet field and thus the molecular photodissociation rates below the disk surface. The full 2D results show significantly higher abundances of radicals such as CN and C2H than previous work, partly due to the fact that CO is dissociated to greater depths. Results for different stellar radiation fields are also presented. The CN/HCN ratio shows a strong dependence on the stellar spectrum, whereas other ratios such as HCO+/CO show only little variation.