低温Rosseland不透明度与不同的碳和氮丰度
Low temperature Rosseland opacities with varied abundances of carbon and nitrogen
摘要：
我们试图产生低温不透明度数据，将不同丰度的元素碳和氮的影响。对于我们感兴趣的温度范围，分子代表主要的不透明度来源。我们的数据集涵盖了广泛的金属丰度范围，旨在为恒星演化模型和其他应用提供重要的输入数据。我们进行化学平衡计算，以评估中性原子，离子和分子的分压。基于一个包含原子线和连续谱数据的大型数据集，最重要的是，大量的分子线，我们不仅计算了许多不同金属丰度的Rosseland平均不透明度系数，而且还计算了每个金属丰度下同位素^{12}C和^{14}N的不同丰度。分子数据包括富氧或富碳化学的主要不透明度来源。我们把不透明度系数作为温度和密度的函数列成表格。由于CO分子的特殊作用，在一定的化学体系中，碳丰度的改变会引起Rosseland不透明度的显著变化。从一个规模化的太阳能（i。e.富氧）混合物转变为富碳状态导致不透明度，在低温下，不透明度与初始情况相差几个数量级。原因是在任一情况下的平均不透明度是由于不同的分子吸收剂。氮丰度的变化影响不太明显，但也不能忽视。[删节]
英文摘要：
We attempt to produce low temperature opacity data incorporating the effects of varied abundances of the elements carbon and nitrogen. For our temperature range of interest, molecules represent the dominant opacity source. Our dataset covers a wide metallicity range and is meant to provide important input data for stellar evolution models and other applications. We conduct chemical equilibrium calculations to evaluate the partial pressures of neutral atoms, ions, and molecules. Based on a large dataset containing atomic line and continuum data and, most importantly, a plethora of molecular lines, we calculate Rosseland mean opacity coefficients not only for a number of different metallicities, but also for varied abundances of the isotopes ^{12}C and ^{14}N at each metallicity. The molecular data comprise the main opacity sources for either an oxygen-rich or carbon-rich chemistry. We tabulate the opacity coefficients as a function of temperature and, basically, density. Due to the special role of the CO molecule, within a certain chemistry regime an alteration to the carbon abundance causes considerable changes in the Rosseland opacity. The transition from a scaled solar (i. e. oxygen-rich) mixture to a carbon-rich regime results in opacities that can, at low temperatures, differ by orders of magnitude from to the initial situation. The reason is that the mean opacity in either case is due to different molecular absorbers. Variations in the abundance of nitrogen have less pronounced effects but, nevertheless, cannot be neglected. [abridged]
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