Experimental studies on the low-temperature condensation of cosmic dust in the interstellar medium

宇宙尘埃在星际介质中低温凝结的实验研究

• 批准号: 203319474
• 负责人: Dr. Cornelia Jäger
• 金额: --
• 依托单位: Laboratory Astrophysics and Cluster Physics Group
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203319474?language=en
• 关键词: Experimental; studies; low; temperature; condensation

An efficient dust formation process in the ISM at temperatures of about 10 to 20 K is required to keep the balance between dust destruction and formation processes. This process is supposed to occur in molecular clouds where gaseous refractory species accrete on surviving dust grains and finally form a solid layer on those grains. In the first project phase, the cold condensation of siliceous and carbonaceous solids without additional energy has been experimentally proven. The structure and composition of the condensed layers is similar to dust materials that are formed in circumstellar shells of evolved stars. In the second project phase, we focus our activities on the simultaneous accretion of carbonaceous and siliceous species on cold surfaces and the final formation of solid materials from atomic and molecular precursors. Since observations of interstellar dust clearly verify the formation of separated silicates and carbonaceous grains even though siliceous and carbonaceous gaseous species may react to form carbides or silicon organic compounds, we will study possible scenarios that may prevent the formation of carbides or compounds having C-Si bonds. The role of VUV photons that may trigger desorption processes of specific molecular species or chemical reactions provoking selective condensation processes has to be studied experimentally. The spectral properties of such condensates, efficiencies of carbon and silicate formation for different ratios of carbonaceous and siliceous species that accrete on the surfaces of grains, and the chemical bonds at interfaces with regard to the spectral properties will be studied to completely understand the cold condensation process of interstellar dust.

在大约10至20 K的温度下，ISM中有效的灰尘形成过程是需要保持尘埃破坏和地层过程之间的平衡。这个过程应该发生在分子云中，在这种云中，气态耐火物种会在存活的尘土颗粒上积聚，并最终在这些晶粒上形成坚固的层。在第一个项目阶段，实验证明了硅质和碳质固体的冷凝结。冷凝层的结构和组成类似于在进化恒星的壳壳中形成的灰尘材料。在第二个项目阶段，我们将活动集中在冷表面上同时吸收碳和硅质物种，以及原子和分子前体的最终形成固体材料。由于对星际尘埃的观察清楚地验证了分离的硅酸盐和碳质晶粒的形成，即使硅质和碳质气态物种可能会反应形成碳化物或硅有机化合物，我们将研究可能防止具有C-SI键的碳化物或化合物的形成的情况。 VUV光子可能触发特定分子物种的解吸过程或化学反应引发选择性凝结过程的作用。这种冷凝物的光谱特性，碳和硅酸盐形成的效率和硅质物种的不同比率，这些碳和硅质物种在谷物表面上积聚的碳和硅质物种的效果，以及界面上的化学键在光谱特性方面，以完全理解特内格拉粉的冷凝结过程。