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Astrochemical Properties of Planck Cold Clumps

By Ken'ichi Tatematsu, Tie Liu, Satoshi Ohashi, Patricio Sanhueza, Quang Nguyen Luong, Tomoya Hirota, Sheng-Yuan Liu, Naomi Hirano, Minho Choi, Miju Kang, Mark A. Thompson, Gary Fuller, Yuefang Wu, Di Li, James Di Francesco, Kee-Tae Kim, Ke Wang, Isabelle Ristorcelli, Mika Juvela, Hiroko Shinnaga, Maria Cunningham, Masao Saito, Jeong-Eun Lee, L. Viktor Toth, Jinhua He, Takeshi Sakai, Jungha Kim, JCMT Large Program SCOPE Collabora and TRAO Key Science Program TOP Colla

Abstract

We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N2H+ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, (HNC)-C-13, N2D+, and cyclic-C3H2 toward nine clumps. The detection rate of N2D+ is 50%. Furthermore, we observed the NH3 emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (less than or similar to 20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N2H+ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N2D+. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps

Topics: ISM: clouds, ISM: molecules, ISM: structure, stars: formation, MOLECULAR CLOUD CORES, STAR-FORMING REGIONS, INFRARED DARK CLOUDS, 45-M RADIO TELESCOPE, DENSE CORES, DEUTERIUM FRACTIONATION, CHEMICAL VARIATION, MAPPING OBSERVATIONS, PHYSICAL CONDITIONS, ANGULAR-MOMENTUM, 115 Astronomy, Space science, ISM: clouds, ISM: molecules, ISM: structure, stars: formation, MOLECULAR CLOUD CORES, STAR-FORMING REGIONS, INFRARED DARK CLOUDS, 45-M RADIO TELESCOPE, DENSE CORES, DEUTERIUM FRACTIONATION, CHEMICAL VARIATION, MAPPING OBSERVATIONS, PHYSICAL CONDITIONS, ANGULAR-MOMENTUM, 115 Astronomy, Space science
Publisher: IOP Publishing
Year: 2017
OAI identifier: oai:helda.helsinki.fi:10138/179110
Journal:

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