Depletion of CCS in a Candidate Warm-Carbon-Chain-Chemistry Source L483

TL;DR

This study uses VLA observations to analyze CCS distribution in the protostellar core L483, revealing unexpected depletion at the center and suggesting CCS traces the outer cold envelope in early chemical stages.

Contribution

It provides new insights into the spatial distribution of CCS in L483, challenging previous expectations and indicating its role as a tracer of early-stage cold envelopes in WCCC sources.

Findings

CCS is depleted at the core center in L483.

CCS traces the outer cold envelope, not the core center.

High CCS abundance may indicate a younger chemical stage.

Abstract

We have carried out an observation of the CCS ($J_{N}$=2$_{1}-$1$_{0}$) line with the Very Large Array in its D-configuration toward a protostellar core L483 (IRAS~18140$-$0440). This is a candidate source of the newly found carbon-chain rich environment called "Warm-Carbon-Chain-Chemistry (WCCC)", according to the previous observations of carbon-chain molecules. The CCS distribution in L483 is found to consist of two clumps aligned in the northwest-southeast direction, well tracing the CCS ridge observed with the single-dish radio telescope. The most remarkable feature is that CCS is depleted at the core center. Such a CCS distribution with the central hole is consistent with those of previously observed prestellar and protostellar cores, but it is rather unexpected for L483. This is because the distribution of CS, which is usually similar to that of CCS, is centrally peaked. Our results imply that the CCS ($J_{N}$=2$_{1}-$1$_{0}$) line would selectively trace the outer cold envelope in the chemically less evolved phase that is seriously resolved out with the interferometric observation. Thus, it is most likely that the high abundance of CCS in L483 relative to the other WCCC sources is not due to the activity of the protostar, although it would be related to its younger chemical evolutionary stage, or a short timescale of the prestellar phase.