SIMBAD references

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/HN¹³C in CB130-3 and L673-SMM4 are found to be 1.28^+0.27_–0.05 and 1.96^+0.32_–0.01, 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.