An Ice Age JWST inventory of dense molecular cloud ices
An Ice Age JWST inventory of dense molecular cloud ices
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DOI：
10.1038/s41550-022-01875-w
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发表时间：
2023-01-23
期刊：
影响因子：
14.1
通讯作者：
Linnartz, H.
中科院分区：
文献类型：
--
作者：
McClure, M. K.;Rocha, W. R. M.;Linnartz, H.
冰粒地幔是挥发性元素的主要储存库，这些挥发性元素将黑暗的星际云中的化学过程与行星的形成及其大气成分联系起来。在星星开始形成之前，最初的冰的成分是在分子云的寒冷而密集的部分。凭借詹姆斯·韦伯太空望远镜的灵敏度，现在可以对冰演化的这一关键阶段进行详细研究。在这里，我们展示了早期发布科学计划冰河时代的初步结果，揭示了这些密集云冰的丰富成分。在沿着两条星前视线上探测到了弱冰特征，包括（CO 2）-C-13、OCN-、（CO）-C-13、OCS和复杂的有机分子官能团。（CO2）-C-12冰剖面表明冰粒的适度增长。列密度的主要和次要的冰种表明，冰的贡献之间的2%和19%的散装预算的关键C，O，N和S元素。我们的研究结果表明，简单和复杂分子的形成可能早在富含水冰的环境中开始。使用JWST，行星大气中看到的分子可以追溯到它们在致密星际云中形成的冰中的冷起源，在星星形成之前，揭示了化学多样性和复杂性的早期实现。
Icy grain mantles are the main reservoir of the volatile elements that link chemical processes in dark, interstellar clouds with the formation of planets and the composition of their atmospheres. The initial ice composition is set in the cold, dense parts of molecular clouds, before the onset of star formation. With the exquisite sensitivity of the James Webb Space Telescope, this critical stage of ice evolution is now accessible for detailed study. Here we show initial results of the Early Release Science programme Ice Age that reveal the rich composition of these dense cloud ices. Weak ice features, including (CO2)-C-13, OCN-, (CO)-C-13, OCS and complex organic molecule functional groups, are now detected along two pre-stellar lines of sight. The (CO2)-C-12 ice profile indicates modest growth of the icy grains. Column densities of the major and minor ice species indicate that ices contribute between 2% and 19% of the bulk budgets of the key C, O, N and S elements. Our results suggest that the formation of simple and complex molecules could begin early in a water-ice-rich environment.Using JWST, the molecules seen in planetary atmospheres can be traced back to their cold origins in ices formed in dense interstellar clouds, before the onset of star formation, revealing that chemical diversity and complexity is achieved early.