Atomic carbon and CO isotope emission in the vicinity of DR 15

Tomoharu Oka, Satoshi Yamamoto, Mitsuhiro Iwata, Hiroyuki Maezawa, Masafumi Ikeda, Tetsuya Ito, Kazuhisa Kamegai, Takeshi Sakai, Yutaro Sekimoto, Ken'ichi Tatematsu, Yuji Arikawa, Yoshiyuki Aso, Takashi Noguchi, Sheng Cai Shi, Keisuke Miyazawa, Shuji Saito, Hiroyuki Ozeki, Hideo Fujiwara, Masatoshi Ohishi, Junji Inatani

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


We present observations of the 3P1-3P0 fine-structure transition of atomic carbon [C I], the J = 3-2 transition of CO, and the J = 1-0 transitions of 13CO and C18O toward DR 15, an H 11 region associated with two mid-infrared dark clouds (IRDCs). The 13CO and C18O J = 1-0 emissions closely follow the dark patches seen in optical wavelength, showing two self-gravitating molecular cores with masses of 2000 and 900 M, respectively, at the positions of the cataloged IRDCs. Our data show a rough spatial correlation between [C I] and 13CO J = 1-0. Bright [C I] emission occurs in the relatively cold gas behind the molecular cores but does not occur in either highly excited gas traced by CO J = 3-2 emission or in the H II region/molecular cloud interface. These results are inconsistent with those predicted by standard photodissociation region models, suggesting an origin for interstellar atomic carbon unrelated to photodissociation processes.

Original languageEnglish
Pages (from-to)176-184
Number of pages9
JournalAstrophysical Journal
Issue number1 PART 1
Publication statusPublished - 2001 Sept 1
Externally publishedYes


  • H II regions
  • ISM: Atoms
  • ISM: Molecules
  • Radio lines: ISM

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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