Molecular Cloud Cores with a High Deuterium Fraction : Nobeyama Single-pointing Survey

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Kim , G , Tatematsu , K , Liu , T , Yi , H-W , He , J , Hirano , N , Liu , S-Y , Choi , M , Sanhueza , P , Toth , L V , Evans , N J , Feng , S , Juvela , M , Kim , K-T , Vastel , C , Lee , J-E , Lu'o'ng , Q N , Kang , M , Ristorcelli , I , Feher , O , Wu , Y , Ohashi , S , Wang , K , Kandori , R , Hirota , T , Sakai , T , Lu , X , Thompson , M A , Fuller , G A , Li , D , Shinnaga , H & Kim , J 2020 , ' Molecular Cloud Cores with a High Deuterium Fraction : Nobeyama Single-pointing Survey ' , Astrophysical Journal Supplement Series , vol. 249 , no. 2 , 33 .

Title: Molecular Cloud Cores with a High Deuterium Fraction : Nobeyama Single-pointing Survey
Author: Kim, Gwanjeong; Tatematsu, Ken'ichi; Liu, Tie; Yi, Hee-Weon; He, Jinhua; Hirano, Naomi; Liu, Sheng-Yuan; Choi, Minho; Sanhueza, Patricio; Toth, L. Viktor; Evans, Neal J.; Feng, Siyi; Juvela, Mika; Kim, Kee-Tae; Vastel, Charlotte; Lee, Jeong-Eun; Lu'o'ng, Quang Nguyen; Kang, Miju; Ristorcelli, Isabelle; Feher, Orsolya; Wu, Yuefang; Ohashi, Satoshi; Wang, Ke; Kandori, Ryo; Hirota, Tomoya; Sakai, Takeshi; Lu, Xing; Thompson, Mark A.; Fuller, Gary A.; Li, Di; Shinnaga, Hiroko; Kim, Jungha
Contributor organization: Department of Physics
Date: 2020-08
Language: eng
Number of pages: 53
Belongs to series: Astrophysical Journal Supplement Series
ISSN: 0067-0049
Abstract: We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments (lambda Orionis, Orion A, Orion B, the Galactic plane, and high latitudes) to identify dense cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores in eight molecular lines at 76-94 GHz using the Nobeyama 45 m telescope. We find that early-type molecules (e.g., CCS) have low detection rates and that late-type molecules (e.g., N(2)H(+)and c-C3H2) and deuterated molecules (e.g., N(2)D(+)and DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction (D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between the D/H pair of lines for distant cores (>1 kpc). For lambda Orionis, Orion A, and Orion B located at similar distances, D/H is not significantly different, suggesting that there is no systematic difference in the observed chemical properties among these three regions. We identify at least eight high-D/H cores in the Orion region and two at high latitudes, which are most likely to be close to the onset of star formation. There is no clear evidence of the evolutionary change in turbulence during the starless phase, suggesting that the dissipation of turbulence is not a major mechanism for the beginning of star formation as judged from observations with a beam size of 0.04 pc.
Subject: Clouds
Interstellar molecules
Star formation
115 Astronomy, Space science
Peer reviewed: Yes
Rights: other
Usage restriction: openAccess
Self-archived version: acceptedVersion

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