Detection of Two Carbon-Chain-Rich Cores; CB130-3 and L673-SMM4

TL;DR

This study identifies two dense dark cloud cores, CB130-3 and L673-SMM4, with high carbon-chain molecule abundance, suggesting they are chemically young regions potentially representing early stages of dark cloud core evolution.

Contribution

The paper reports the discovery of two dense cores with unusually high carbon-chain molecules, indicating they are candidate carbon-chain-producing regions, expanding understanding of chemical evolution in dark clouds.

Findings

CB130-3 and L673-SMM4 have high CCS and HC3N abundances.

Deuterium fractionation ratios are comparable to or higher than known CCPRs.

These cores are likely slightly older than similar regions in Taurus.

Abstract

We have found two dense cores, CB130-3 and L673-SMM4, where the carbon-chain molecules are extremely abundant relative to NH$_{3}$, during a survey observation of radio emission lines of CCS, HC$_{3}$N, HC$_{5}$N, and NH$_{3}$ toward dark cloud cores. Judging from the low NH$_{3}$/CCS ratios, they are possible candidates for "Carbon-Chain--Producing Regions (CCPRs)" recognized as chemically young dark cloud cores. The deuterium fractionation ratios DNC/HN$^{13}$C 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.