THE D/H RATIO OF WATER ICE AT LOW TEMPERATURES
THE D/H RATIO OF WATER ICE AT LOW TEMPERATURES
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低温下水冰的 D/H 比
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
E. Bergin
中科院分区：
文献类型：
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作者：
Jeong;E. Bergin
我们提出的模拟结果的氘分馏水冰，H2，并采用物理条件与星星和行星的形成过程中的主要氘同位素。我们计算了氘化学的气体温度范围（Tgas 10-30 K），分子氢密度（n（H2）104-107），和邻/帕拉比（opr）的基础上状态到状态的反应速率和探索所产生的分馏，包括形成水冰地幔涂层颗粒表面。我们发现，氘分馏表现出预期的温度依赖性的大富集在低气体温度。更重要的是，水冰的形成导致了水冰中大的D/H比（10 K时为10 - 2），但也改变了整体的氘化学性质。对于T < 20 K，氘注入冰中降低了HD的总体丰度，这降低了高密度下氘分馏的效率。与先前的研究一致，在这些条件下，HD可能不是冷的致密星际介质中的主要氘库，而是星前核和原行星盘中平面的致密中心的主要电荷载体。
We present the modeling results of deuterium fractionation of water ice, H2, and the primary deuterium isotopologues of adopting physical conditions associated with the star and planet formation process. We calculated the deuterium chemistry for a range of gas temperatures (Tgas ∼ 10–30 K), molecular hydrogen density (n(H2) ∼ 104–107), and ortho/para ratio (opr) of H2 based on state-to-state reaction rates and explore the resulting fractionation including the formation of a water ice mantle coating grain surfaces. We find that the deuterium fractionation exhibits the expected temperature dependence of large enrichments at low gas temperature. More significantly, the inclusion of water ice formation leads to large D/H ratios in water ice (≳ 10−2 at 10 K) but also alters the overall deuterium chemistry. For T < 20 K, the implantation of deuterium into ices lowers the overall abundance of HD which reduces the efficiency of deuterium fractionation at high density. In agreement with an earlier study, under these conditions HD may not be the primary deuterium reservoir in the cold dense interstellar medium and will be the main charge carrier in the dense centers of pre-stellar cores and the protoplanetary disk midplane.