The HD molecules are key species for the cooling of pristine gas at temperatures below 100 K. They are also known to be key tracers of H₂ in protoplanetary disks and thus, they can be used as a measure of protoplanetary disks mass. Accurate modeling of the cooling mechanism and of HD abundance in astrophysical media requires a proper modeling for its excitation by both radiative and collisional processes. Here, we report quantum time-independent calculations of collisional rate coefficients for the rotational excitation of HD by H for temperatures ranging from 10 to 1000 K. The reactive and hydrogen exchange channels are taken into account in the scattering calculations. New exact quantum results are compared to previous calculations performed neglecting reactive and exchange channels. We found that for temperatures higher than ∼300 K, the impact of these channels on the rate coefficients cannot be neglected. Such results suggest that the new HD–H collisional data have to be used for properly modeling HD cooling function and HD abundance in all the astrophysical environments where HD plays a role, e.g. in photon-dominated regions, protoplanetary disks, early Universe chemistry, and primordial star forming regions.

中文翻译：

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再论氢对HD的旋转激发

HD分子是在低于100 K的温度下冷却原始气体的关键物质。它们也被称为H _2的关键示踪剂。因此，它们可以用作原行星盘质量的度量。对天体物理介质中冷却机制和HD丰度的准确建模需要通过辐射过程和碰撞过程对其激发进行适当建模。在这里，我们报告了HD在10至1000 K范围内被H旋转激发的碰撞速率系数的量子时间无关的计算。在散射计算中考虑了反应性和氢交换通道。将新的精确量子结果与忽略反应性和交换通道的先前计算结果进行比较。我们发现，对于高于〜300 K的温度，这些通道对速率系数的影响不可忽略。