Submillimeter, Far-Infrared Spectroscopy of the Interstellar Medium

Abstract

Spectroscopic studies of interstellar clouds can now be made in the submillimeter and far-infrared bands, essentially free from the absorbing effects of the Earth's atmosphere, by means of the NASA Kuiper Airborne Observatory. Also large telescopes for the submillimeter are now under construction on mountain tops. Both high and intermediate resolution spectroscopic techniques have been successfully employed in the detection of many new molecular and atomic lines including rotational transitions of hydrides such as OH , H_20, NH_3 , and HCl; high J rotational transitions of CO; and the ground state fine structure transitions of atomic carbon, oxygen, singly ionized carbon and doubly ionized oxygen and nitrogen. In addition, heavy molecules have prolific spectra in the near millimeter band, and this is expected to extend to the submillimeter. These various submillimeter transitions have been used to study the physics and chemistry of clouds throughout the galaxy, in the galactic center region, and in neighboring galaxies.