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。量子力学计算将对各种在天体物理环境中具有重要意义的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喷发物中的过程。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光子和x射线对星系中分子云结构的影响进行理论研究。将计算氢分子对x射线的红外响应。星际介质（ISM）虽然极其脆弱，但却是许多复杂的原子和分子反应的场所。从本质上讲，所有的元素都以不同的数量存在，它们结合形成不同的分子，如水、氨、酒精，甚至更复杂的物种。此外，还存在较大的冰和尘埃颗粒。然后，这个复杂的介质不断受到各种能量来源的轰击，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的各种大块运动和湍流动能。这种反应性的“汤”很自然地从许多电子跃迁中发射光子，观察这些光子可以得到恒星之间广阔空间中物理和化学条件的数据。然而，由于涉及的复杂性，对ISM观测结果的解释并不直截了当，需要实验室测量和量子力学计算才能理解。达尔加诺博士备受推崇的理论研究旨在进一步加深我们对ISM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.