Radio and Millimetre Observations of Larger Molecules

Abstract

The number of known interstellar molecules has increased steadily since 1970 and stands presently at 68. of the molecules discovered in recent years more than half contain three or more heavy elements.The number of sources where HC5N or HC3N has been detected now includes 21 dark clouds, four circumstellar shells, two bipolar nebulae, the line of sight to the Cas A supernova remnant, and possibly a comet. the more abundant large molecules are useful diagnostic probes, and preliminary statistical equilibrium calculations of the widespread new ring, C3H2, are presented which indicate its usefulness as an indicator of H2 density.