LONG CARBON-CHAIN MOLECULES AND THEIR ANIONS IN THE STARLESS CORE, LUPUS-1A

Abstract

We have recently discovered a new starless core with bright radio emissions of long carbon-chain molecules in the Lupus molecular cloud, which we have named as Lupus-1A. Toward this source, the peak intensities of the C6H and C8H lines are found to be higher than toward TMC-1 by a factor of 2–3. Even the lines of their anions, C6H− and C8H−, are also brighter than in TMC-1. Moreover, the line of C4H− has been detected for the first time in a starless core. The column densities of these long carbon-chain molecules are almost comparable to those in TMC-1, and hence, this source can be regarded as the second "TMC-1 like cloud." TMC-1 has long been an outstanding molecular cloud with rich carbon-chain molecules since its discovery in 1976. In spite of extensive efforts, no comparable sources have been found so far. Lupus-1A will be used for hunting of new interstellar molecules as well as understanding of carbon-chain chemistry through critical comparison of physical and chemical properties with TMC-1. This source is important not only for astronomy but also for molecular science as an ideal spectroscopic laboratory because of narrow line shapes and bright intensities.