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

doi:10.1016/S0273-1177(99)00253-7

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

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

Abstract

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 language	English
Pages (from-to)	985-989
Number of pages	5
Journal	Advances in Space Research
Volume	23
Issue number	5-6
DOIs	https://doi.org/10.1016/S0273-1177(99)00253-7
Publication status	Published - 1999
Externally published	Yes

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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@article{79dd0f8fdad74251a42b4a4a3c5e3347,

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

abstract = " We have observed the Galactic center in 12 CO(J = 2-1) and 13 CO(J = 2-1) lines using the Tokyo-Onsala-ESO-Cal{\'a}n 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.",

author = "T. Sawada and T. Hasegawa and T. Handa and Usuda, {K. S.} and Morino, {J. I.} and R. Booth and L. Bronfman and {Luna C.}, A. and M. Hayashi and Nyman, {L. {\AA}} and T. Oka and S. Sakamoto and M. Seta and P. Shaver and K. Sorai",

year = "1999",

doi = "10.1016/S0273-1177(99)00253-7",

language = "English",

volume = "23",

pages = "985--989",

journal = "Advances in Space Research",

issn = "0273-1177",

publisher = "Elsevier Limited",

number = "5-6",

}

TY - JOUR

T1 - A CO(J=2-1) line survey of the Galactic center

AU - Sawada, T.

AU - Hasegawa, T.

AU - Handa, T.

AU - Usuda, K. S.

AU - Morino, J. I.

AU - Booth, R.

AU - Bronfman, L.

AU - Luna C., A.

AU - Hayashi, M.

AU - Nyman, L. Å

AU - Oka, T.

AU - Sakamoto, S.

AU - Seta, M.

AU - Shaver, P.

AU - Sorai, K.

PY - 1999

Y1 - 1999

N2 - 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.

AB - 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.

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U2 - 10.1016/S0273-1177(99)00253-7

DO - 10.1016/S0273-1177(99)00253-7

M3 - Article

AN - SCOPUS:0039134633

SN - 0273-1177

VL - 23

SP - 985

EP - 989

JO - Advances in Space Research

JF - Advances in Space Research

IS - 5-6

ER -

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

Abstract

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