Astrophys. J., Suppl. Ser., 136, 189-219 (2001/September-0)
The Tokyo-Onsala-ESO-Calan galactic CO J=2-1 survey. I. The Galactic Center region.
SAWADA T., HASEGAWA T., HANDA T., MORINO J.-I., OKA T., BOOTH R., BRONFMAN L., HAYASHI M., CASTELLANOS A.L., NYMAN L.-A., SAKAMOTO S., SETA M., SHAVER P., SORAI K. and USUDA K.S.
Abstract (from CDS):
As a part of the Tokyo-Onsala-ESO-Calán Galactic CO survey, we have made large-scale mapping observations of the Galactic center in the CO J=2-1 line using the 60 cm survey telescope in Chile. The data were taken with the same beam size (9') and sampling grid (7'.5) as the CO J=1-0 Columbia survey, so that the two data sets can be compared directly. Velocity channel maps and longitude-velocity diagrams of the 12CO J=2-1 line, covering -6°≤l≤6°, -2°≤b≤2°, -300≤vLSR≤300 km.s–1, are presented, along with the corresponding maps of the 12CO J=2-1/J=1-0 intensity ratio [R2–1/1–0(12CO)]. A longitude-velocity diagram of the 13CO J=2-1 line intensity and corresponding 13CO J=2-1/12CO J=2-1 intensity ratio [R13/12(J=2-1)] is also presented at b=0°. The overall R2–1/1–0(12CO) in the central 900 pc of the Galaxy is 0.96±0.01, which is higher than the typical value in the Galactic disk, 0.6-0.7. The isotopic intensity ratio R13/12(J=2-1) is 0.10±0.01. The two observed intensity ratios [R2–1/1–0(12CO) and R13/12(J=2-1)] indicate that the optical depth of the 12CO J=1-0 line is ∼1 or smaller in the Galactic center molecular clouds, much smaller than those of the giant molecular clouds (GMCs) in the Galactic disk. Longitude-velocity distributions of physical properties of molecular gas are derived using a large velocity gradient analysis. Molecular gas in the Galactic center generally shows a high pressure. In particular, there is a high-pressure region in the central ∼100 pc where the pressure is an order of magnitude higher than that in GMCs in the Galactic disk. This region is dominated by high-density gas and contains star-forming regions.
Galaxy: Center - ISM: Clouds - ISM: Molecules - Radio Lines: ISM - Surveys
View the reference in ADS
To bookmark this query, right click on this link: simbad:2001ApJS..136..189S and select 'bookmark this link' or equivalent in the popup menu