Chemical evolution in the interstellar medium

CHED 1626

Louis J. Allamandola, lallamandola@mail.arc.nasa.gov, Astrochemistry Laboratory, NASA Ames Research Center, M/S 245-6, Moffett Field, CA 94035
Great strides have been made in our understanding of interstellar material thanks to advances in infrared astronomy and laboratory astrophysics. Ionized polycyclic aromatic hydrocarbons (PAHs), shockingly large molecules by earlier astrochemical standards, are widespread and very abundant throughout much of the cosmos. In cold molecular clouds, the birthplace of planets and stars, interstellar molecules freeze onto dust and ice particles forming mixed molecular ices dominated by simple species such as water, methanol, ammonia, and carbon monoxide. Within these clouds, and especially in the vicinity of star and planet forming regions, these ices and PAHs are processed by ultraviolet light and cosmic rays forming hundreds of far more complex species, some of biogenic interest. Eventually, these are delivered to primordial planets by comets and meteorites. The chemical context, highlights of this field from a chemist's perspective, and the astronomer's infrared toolbox will be reviewed.