DETECTION OF TWO CARBON-CHAIN-RICH CORES: CB130-3 AND L673-SMM4

We have found two dense cores, CB130-3 and L673-SMM4, where the carbon-chain molecules are extremely abundant relative to NH3, during a survey observation of radio emission lines of CCS, HC3N, HC5N, and NH3 toward dark cloud cores. Judging from the low NH3/CCS ratios, they are possible candidates for Carbon-Chain-Producing Regions (CCPRs) recognized as chemically young dark cloud cores. The deuterium fractionation ratios DNC/(HNC)-C-13 in CB130-3 and L673-SMM4 are found to be 1.28(-0.05)(+0.27) and 1.96(-0.01)(+0.32), respectively, which are comparable to or slightly higher than those in CCPRs found previously. We suggest that the dense cores of CB130-3 and L673-SMM4 are analogous to CCPRs, but their chemical evolutionary phase would be slightly older than those of the dense cores in the Taurus region.