Identification of features due to H3 + in the infrared spectrum of supernova 1987A
Identification of features due to H3 + in the infrared spectrum of supernova 1987A
复制标题
超新星 1987A 红外光谱中 H3 特征的识别
作者：
S. Miller;J. Tennyson;S. Lepp;A. Dalgarno
分子离子H3 +在星际化学理论模型中占据中心位置。当电离的H2与中性H2反应时，它很容易在富含氢的星际气体云中形成。然后H3 +离子可以向氧、碳和其他重原子提供一个质子。从这开始，形成了近100种不同的星际分子，如活性羟基OH，中性CO，乙醇，线性聚乙炔HCxN和环状物质如环丙烯叉，C3H3。但是，尽管经过了十年的探索，H3 +除了在富氢的大气层中外，一直没有被探测到。在这里，我们提出了H3 +存在于超新星1987A的包层中的证据，在那里它是由一种不寻常的化学反应产生的，其中激发的氢原子是分子形成的主要来源。SN 1987 A（参考文献6）在爆炸后的最初几百天内的红外光谱包含两个先前未识别的峰，我们将其归因于H3 +。化学建模产生的H3 +量与观察到的峰强度一致，也预测了大量的HeH+，这可能是光谱中一些较弱的特征的原因。
THE molecular ion H3 + occupies a central position in theoretical models of interstellar chemistry1,2. It forms readily in hydrogen-rich interstellar gas clouds when ionized H2 reacts with neutral H2. The H3 + ion can then donate a proton to oxygen, carbon and other heavy atoms. From this beginning nearly 100 different inter-stellar molecules are formed, such as the reactive hydroxyl radical OH, neutral CO, ethanol, the linear polyacetylenes HCxN and cyclic species such as cyclopropenylidene, C3H3. But in spite of a decade of searching3,4, H3 + has eluded detection except in the hydrogen-rich atmosphere of Jupiter5. Here we present evidence for the presence of H3 + in the envelope of supernova 1987A, where it is produced by an unusual chemistry in which excited hydrogen atoms are the main source of molecule formation. Infrared spectra of SN1987A (ref. 6) in the first few hundred days after the explosion contain two previously unidentified peaks which we attribute to H3 +. Chemical modelling produces quantities of H3 + consistent with the observed peak intensities, and also predicts significant amounts of HeH+, which may be responsible for some weaker features in the spectra.