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Depletion of CCS in a Candidate Warm-Carbon-Chain-Chemistry Source L483
We have carried out an observation of the CCS (=21) line
with the Very Large Array in its D-configuration toward a protostellar core
L483 (IRAS~181400440). 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 (=21) 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.Comment: 10 pages, 3 figures, accepted for publication in ApJ Part
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