Polycyclic aromatic hydrocarbon formation in carbon-rich stellar envelopes
Polycyclic aromatic hydrocarbon formation in carbon-rich stellar envelopes
复制标题
富碳恒星包层中多环芳烃的形成
DOI：
10.1086/173012
复制
发表时间：
1992
期刊：
影响因子：
--
通讯作者：
A. Tielens
中科院分区：
文献类型：
--
作者：
I. Cherchneff;J. Barker;A. Tielens
为了研究富碳恒星流出中多环芳烃分子的形成，对恒星包层气体密度和温度分布进行了详细的化学动力学模拟。通过积分耦合的连续性方程，计算了几种包络模型的化学浓度分布，其中包括从激波形成半径处的内边界开始球状扩展的流动。研究了小分子多环芳烃所经历的“逆温室”效应的影响，结果表明，小分子多环芳烃的产量可提高许多个数量级。结果表明，炔丙基自由基途径可能是产生苯的一个重要途径。多环芳烃的生成量对气体密度和温度非常敏感，并且比从观测到的晚型富碳恒星包层的尘埃含量推断的值要小得多。因此，芳香族分子不太可能在恒星流出过程中产生。
A detailed chemical kinetic scheme is applied to stellar envelope profiles of gas density and temperature profiles in order to study the formation of PAH molecules in carbon-rich stellar outflows. Chemical concentration profiles are calculated for several envelope models by integrating the coupled continuity equations that include spherically expanding flows from an inner boundary at the shock formation radius. The influence of the 'inverse greenhouse' effect experienced by small PAHs is investigated and shown to increase the PAH yield by many orders of magnitude. It is shown that the route through propargyl radicals could be an important channel to produce benzene. PAH formation yields are found to be extremely sensitive to gas density and temperature and are much smaller than values inferred from the observed dust content of late-type carbon-rich stellar envelopes. It is therefore unlikely that aromatic molecules are generated in the stellar outflow itself.