Detection of a new carbon-chain molecule, CCO

Abstract

We have detected a new carbon-chain molecule, CCO(3∑-), in the cold, dark molecular cloud TMC-1. The excitation temperature and the column density of CCO are, respectively, ∼6 K and ∼6 × 1011 cm-2. This column density corresponds to a fractional abundance relative to H2 of ∼6 × 10-11. This value is two orders of magnitude less than the abundance of the related carbon-chain molecule CCS, and about half that of C3O. The formation mechanism for CCO is discussed.