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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Monte Carlo studies of surface chemistry and nonthermal desorption involving interstellar grains
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Monte Carlo studies of surface chemistry and nonthermal desorption involving interstellar grains

机译：蒙特卡洛研究涉及星际晶粒的表面化学和非热解吸

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摘要

Although still poorly understood, the chemistry that occurs on the surfaces of interstellar dust particles profoundly affects the growth of molecules in the interstellar medium. The most important surface reaction is the conversion of atomic to molecular hydrogen, which is a precursor for all subsequent molecular development and which occurs both in diffuse and dense interstellar clouds. Another set of surface reactions produces icy mantles of many monolayers in cold and dense regions of the interstellar medium. The monolayers are dominated by water ice but also contain CO, CO2, and occasionally methanol. In this work, we first review both our stochastic approach to the surface chemistry that can occur on small dust particles and how it has been applied to the problem of the formation of molecular hydrogen. This latter problem is strongly affected by the pulsed heating of smaller grains by photons. Photons are not the only source of pulsed heating; cosmic rays also can heat interstellar grains in a pulsed manner. Here, we calculate the heating by cosmic rays for different grain sizes and cosmic ray components. It is then shown that this mechanism is an important one for desorption of ice mantles.
机译：尽管仍知之甚少，星际尘埃颗粒表面上发生的化学反应深刻影响着星际介质中分子的生长。最重要的表面反应是原子到分子氢的转化，这是所有后续分子发展的前兆，同时发生在弥散和密集的星际云中。另一组表面反应在星际介质的寒冷和稠密区域产生许多单层的冰冷地幔。单层以水冰为主，但也含有CO，CO2，偶尔还有甲醇。在这项工作中，我们首先回顾一下我们对小尘埃颗粒可能发生的表面化学的随机方法，以及如何将其应用于解决分子氢的形成问题。后一个问题受到光子对较小晶粒的脉冲加热的强烈影响。光子不是脉冲加热的唯一来源。宇宙射线还可以脉冲方式加热星际谷物。在这里，我们通过宇宙射线计算不同晶粒尺寸和宇宙射线分量的热量。然后表明，该机制是解冻冰幔的重要机制。

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