The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus.

中文翻译：

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彗星中的HNC / HCN比。

通过观察两个物种在日心距为0.93 <r <3 AU时对两个物种的J = 4-3旋转跃迁进行观测，研究了Hale-Bopp彗星（C / 1995 O1）中HCN和HNC异构体的丰度比。和后perihelion。校正更强的HCN线的光学深度后，我们发现，随着彗星接近太阳，我们的望远镜光束中HNC / HCN的列密度比显着增加。我们将该行为与根据离子分子化学模型预测的行为进行了比较，并得出结论，HNC在很大程度上是由昏迷中的化学过程产生的；也就是说，对于Hale-Bopp彗星来说，HNC不是从原子核升华的母体分子。