A CO(J=2-1) line survey of the Galactic center

T. Sawada, T. Hasegawa, T. Handa, K. S. Usuda, J. I. Morino, R. Booth, L. Bronfman, A. Luna C., M. Hayashi, L. Å Nyman, T. Oka, S. Sakamoto, M. Seta, P. Shaver, K. Sorai

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2 Citations (Scopus)


We have observed the Galactic center in 12 CO(J = 2-1) and 13 CO(J = 2-1) lines using the Tokyo-Onsala-ESO-Calán 60-cm telescope and compared the data with the 12 CO(J = 1-0) Columbia survey (Bitran et al. 1997). The 12 CO J = 2-1/J = 1-0 intensity ratio is very high (0.96) in the central 900 pc of the Galaxy, although it is about 0.6-0.7 for typical molecular clouds in the Galactic disk. The observed intensity ratios, 12 CO J = 2-1/J = 1-0 and 13 CO/ 12 CO (J = 2-1), indicate that even the 12 CO line is not very optically thick: τ12 CO(J=1-0) ∼ 1 or smaller in the Galactic center. This may be due to high temperature and large velocity dispersion. The large velocity dispersion is probably caused by large external pressure and tidal forces.

Original languageEnglish
Pages (from-to)985-989
Number of pages5
JournalAdvances in Space Research
Issue number5-6
Publication statusPublished - 1999
Externally publishedYes

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences(all)


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