Theoretical Studies of Interstellar Matter

达尔加诺博士将继续研究星际介质中的化学过程。量子力学计算将对天体物理环境中重要的各种原子和分子过程进行，特别关注发生在星际介质和超新星1987A喷发中的过程。将对超新星、星际云的电离结构、加热和冷却机制、分子组成以及紫外线和X射线对星系分子云结构的影响进行理论研究。我们将计算分子氢对X射线的红外响应。尽管星际介质(ISM)极其稀薄，但它是许多复杂原子和分子反应的场所。基本上，所有的元素都以不同的数量存在，众所周知，它们结合在一起形成了不同的分子，如水、氨、酒精，甚至更复杂的物种。此外，还存在较大的冰粒和尘埃。然后，这种复杂的介质不断地受到各种能源的轰击，包括宇宙射线、X射线、低能和高能光子、原子和分子之间的碰撞、冲击波、ISM的各种整体运动和湍动能。这种反应性的“汤”相当出人意料地从许多电子跃迁中发射出光子，通过观察这些光子，可以获得关于恒星之间广阔空间的物理和化学条件的数据。然而，由于涉及的复杂性，对ISM观测的解释并不简单，需要实验室测量和量子力学计算才能理解。达尔加诺博士高度重视的理论研究旨在加深我们对ISM中的成分和活动的理解。

Dr. Dalgarno will continue research on the chemical processes in the interstellar medium. Quantum mechanical calculations will be carried out on a variety of atomic and molecular processes that are significant in astrophysical environments with particular attention to processes occurring in the interstellar medium and in the ejecta of supernova 1987A. Theoretical studies will be performed on the ionization structure, heating and cooling mechanisms and the molecular composition of supernovae, interstellar clouds, and the influence of ultraviolet photons and X-rays on the structure of molecular clouds in galaxies. The infrared response of molecular hydrogen to X-rays will be calculated. Although it is extremely tenuous, the interstellar medium (ISM) is the site of many complicated atomic and molecular reactions. Essentially all elements are present in varying quantities, and they are known to combine to form diverse molecules such as water, ammonia, alcohol, and even more complicated species. Also, larger particles of ice and dust are present. This complicated medium is then continually bombarded with various sources of energy including cosmic rays, X-rays, low and high energy photons, collisions between atoms and molecules, shock waves, various bulk movements of the ISM, and turbulent kinetic energy. This reactive "soup" quite expectedly emits photons from many electronic transitions and observing these gives data on the physical and chemical conditions in the vast space between the stars. However, because of the complications involved, interpretation of ISM observations is not straightforward and requires laboratory measurements and quantum mechanical calculations for their understanding. Dr. Dalgarno's highly regarded theoretical research is directed toward furthering our understanding of the constituents and activity in the ISM.