Distribution of the [C I] emission in the ρ Ophiuchi dark cloud

Kazuhisa Kamegai, Masafumi Ikeda, Hiroyuki Maezawa, Tetsuya Ito, Mitsuhiro Iwata, Takeshi Sakai, Tomoharu Oka, Satoshi Yamamoto, Yutaro Sekimoto, Ken'ichi Tatematsu, Takashi Noguchi, Shuji Saito, Hideo Fujiwara, Hiroyuki Ozeki, Junji Inatani, Masatoshi Ohishi

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31 Citations (Scopus)


The 3P1-3P0 fine-structure line of the neutral carbon atom ([C I]) has been mapped over the 1°.8 × 1°.3 area of the L1688 cloud in the ρ Ophiuchi region with the Mount Fuji submillimeter-wave telescope. The 3P2- 3P1 line of [C I] has also been observed toward two representative positions to evaluate the excitation temperature of the [C I] lines. The overall extent of the [C I] distribution generally resembles that of the 13CO distribution. The [C I] distribution has two major peaks; one (peak I) is at ρ Oph A, and the other (peak II) is toward the east side of the C18O core in the southern part of L1688. Peak II is located beyond the C18O core with respect to the exciting star HD 147889. The C0 column density is 5.0 × 1017 cm-2 toward peak II. The spatial distribution of the [C I] emission is compared with plane-parallel photodissociation region (PDR) models, which suggest that peak II is associated with a lower density PDR front, adjacent to the dense cloud cores observed in the C18O line emission. Alternatively, peak II is in the early stage of chemical evolution, where C0 has not been completely converted to CO. In this case, the difference in the [C I] and C 18O distributions represents an evolutionary sequence. This is consistent with a picture of a shock-compressed formation of the dense cores in this region due to influences from the Sco OB2 association.

Original languageEnglish
Pages (from-to)378-385
Number of pages8
JournalAstrophysical Journal
Issue number1 I
Publication statusPublished - 2003 May 20
Externally publishedYes


  • ISM: atoms
  • ISM: clouds
  • ISM: individual (L1688, ρ Ophiuchi)
  • Submillimeter

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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