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

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

Abstract

We have observed the Galactic center in 12CO(J = 2-1) and 13CO(J = 2-1) lines using the Tokyo-Onsala-ESO-Calán 60-cm telescope and compared the data with the 12CO(J = 1-0) Columbia survey (Bitran et al. 1997). The 12CO 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, 12CO J = 2-1/J = 1-0 and 13CO/ 12CO (J = 2-1), indicate that even the 12CO line is not very optically thick: ?12 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. © 1999 COSPAR. Published by Elsevier Science Ltd.

Más información

Título de la Revista: ADVANCES IN SPACE RESEARCH
Volumen: 23
Número: 5-6
Editorial: ELSEVIER SCI LTD
Fecha de publicación: 1999
Página de inicio: 985
Página final: 989
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-0039134633&partnerID=q2rCbXpz