Collaborative Research: Carriers, Charge State and Diagnostic Use of the Long-Mysterious Diffuse Interstellar Bands

这项工作研究了哪些原子、离子、小分子和大分子会引起某些被称为“弥漫星际带”（DIBs）的星际吸收特征。自20世纪20年代以来，大约有600条与这些星际带家族有关的吸收谱线被发现，但它们与特定分子的联系仍然未知。在这里，在原子和分子光谱学、星际气体和尘埃以及实验室化学方面具有不同专业知识的研究人员聚集在一起，解决这个长期悬而未决的问题。方法是在数据库中编译和组织现有的观测结果，并增加对大约220颗恒星的DIB的新测量，以评估和寻找不同DIB吸收特征以及其他星际参数（如密度和电离状态）之间的经验关系。现有的所有光谱宽度均匀限制的dib列表随着新的观测而扩大，包括仅在某些物理条件下出现的宽窄线。为了这个目的，一个新的恒星图集将被组装起来，用来照亮这些星际区域。另一个目标是观察某些漫射星际云，以获得dib的类型和吸收强度作为密度和电离状态增加的函数，这与特定化合物的空间分布和云内正在进行的反应有关。小组成员已得到保证，可以使用观测设施（例如，阿帕奇角天文台）来完成这部分工作。只要引起DIB吸收的化合物（怀疑有超过15个原子的分子）的类型仍然难以捉摸，就不可能完全解释星际介质的化学库存和过程。dib载体的识别将是理解恒星和行星形成的分子云中的化学库存的重要一步。这个合作项目的跨学科性质非常强。它为本科生和研究生提供了研究与多个学科相关的问题的机会。

This work investigates which atoms, ions, small and large molecules cause certain interstellar absorption features known as "Diffuse Interstellar Bands" (DIBs). About 600 absorption lines associated with these families of interstellar bands are known since the 1920s but their association which specific molecules is still unknown. Here researchers with different expertise in atomic and molecular spectroscopy, interstellar gas and dust, and laboratory chemistry, come together to tackle this long-standing open question. The approach is to compile and organize existing observations in databases and to add new measurements of DIBs seen toward about 220 stars to assess and to search for empirical relations between the different DIB absorption features as well as other interstellar parameters such as density and ionization state. The existing list of DIBs of all spectral widths to uniform limit is expanded with new observations to include broad and narrow lines that only appear under certain physical conditions. For this purpose, a new atlas of stars illuminating such interstellar regions will be assembled. Another goal is to observe certain diffuse interstellar clouds to obtain the types and absorption strengths of DIBs as a function of increasing density and ionization state, which relates to the spatial distribution of particular compounds and on-going reactions within the cloud. The team members have guaranteed access to observing facilities (e.g., Apache Point Observatory) to do this part of work.As long as the types of compounds (molecules with more than 15 atoms are suspected) responsible for the DIB absorptions remain elusive, it is not possible to fully account for the chemical inventory and processes of the interstellar medium. The identification of the carriers of the DIBs will be a major step forward in understanding the chemical inventory in molecular clouds from which stars and planets form.The interdisciplinary nature of this collaborative project is very strong. It provides undergraduate- and graduate students with opportunities to work on problems related to more than one discipline.