Named in honor of Alexander Dalgarno (1928– ), on the occasion of his 70th birthday. Renowned for his seminal research on collisions and radiative processes involving atoms, molecules, ions and electrons, Dalgarno has led the exploration of atmomic and molecular phenomena occurring in the interstellar medium, planetary and cometary atmospheres, supernova ejecta, the early universe and the terrestrial thermosphere. Due to his intellectual leadership, the Institute for Theoretical Atomic and Molecular Physics was established at the Harvard-Smithsonian Center for Astrophysics. He served as director of the Institute for five years and as acting director of the Harvard College Observatory for three years. (M 32347) _ _.