发表机构
Centro de Astrobiología (CAB), INTA-CSIC; Departamento de Física de la Tierra y Astrofísica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid; Instituto de Química Física Blas Cabrera (CSIC); Department of Physics, National Central University（西班牙国家航空航天技术研究所-西班牙国家科学研究委员会天体生物学中心; 马德里康普顿斯大学物理科学学院地球与天体物理学系; 西班牙国家科学研究委员会布拉斯·卡布雷拉物理化学研究所; 中原大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过实验发现，水能显著增强星际冰中难熔硫（如S6-S8）的形成，为稠密云中硫缺失提供了固相储库机制，并可作为水冰环境的示踪剂。
AI 中文摘要
硫是宇宙中第十丰富的元素，然而在稠密星际区域的气相中严重匮乏，这表明硫被封存在难以探测的尘埃颗粒组分中。我们研究含H2S的星际冰类似物经紫外辐照和热加工是否会产生难熔硫物种，以及以水为主的冰是否增强其形成。我们对含H2S的冰类似物（含水和无水）进行了紫外辐照和升温实验，并对所得难熔残留物进行了非原位分析。难熔硫物种，包括硫的同素异形体S6-S8，在含H2S的星际冰类似物的紫外辐照和热加工过程中形成。水将这些硫同素异形体的形成增强了两个数量级。我们提出一个形成机制，其中由水冰基质稳定的离子中间体促进链增长和环化，主要生成S8。在我们的残留物中检测到的硫同素异形体和多硫代物种（也在陨石和小行星返回样品中报道）的联合检测，支持它们在前彗星冰幔中覆盖尘埃颗粒的形成。由于这些物种每分子可包含多个硫原子，它们构成了稠密云环境中（年轻恒星诞生地）缺失硫的有效固相储库。因此，难熔硫可以作为太空中水冰环境的示踪剂。
英文摘要
Sulfur is the tenth most abundant element in space, yet it is strongly depleted in the gas phase of dense interstellar regions, suggesting sequestration in dust grain components that are difficult to detect. We study whether UV irradiation and thermal processing of H2S-containing interstellar-ice analogues can produce refractory sulfur species, and whether water-dominated ice enhances their formation. We performed UV irradiation and warm-up experiments on H2S-containing ice analogues with and without water, and the resulting refractory residues were analysed ex situ. Refractory sulfur species, including the sulfur allotropes S6-S8, are formed during UV irradiation and thermal processing of H2S-containing interstellar-ice analogues. Water enhances the formation of these sulfur allotropes by two orders of magnitude. We propose a formation mechanism in which ionic intermediates stabilised by the water-ice matrix promote chain growth and cyclisation, yielding predominantly S8. The combined detection in our residues of sulfur allotropes and polythionic species, also reported in meteorites and samples returned from asteroids, supports their formation in pre-cometary ice mantles covering dust grains. Because these species can incorporate multiple sulfur atoms per molecule, they constitute an efficient solid-phase reservoir for the missing sulfur in dense cloud environments where young stars are born. Refractory sulfur can therefore serve as a tracer of water-ice environments in space.
CommentsAccepted for publication in Astronomy & Astrophysics (A&A). 5 figures, 1 table
