2001 Fiscal Year Final Research Report Summary
A Study of the Galactic Structure by a Survey of the Southern Milky Way with a Wide-Field Telescope
| Project/Area Number |
09044058
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | University of Tokyo |
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Principal Investigator |
HASEGAWA Tetsuo The University of Tokyo, School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (50134630)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Masahiko National Astronomical Observatory of Japan, Division of Optical and Infrared Astronomy, 光学赤外線天文学研究系, 教授 (10183914)
HANDA Toshihiro The University of Tokyo, School of Science, Assistant Professor, 大学院・理学系研究科, 助手 (40202270)
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| Project Period (FY) |
1997 – 1999
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| Keywords | star formation / interstellar matter / the galaxy / Magellanic clouds / millimeter / submillimeter waves / radio astronomy / survey / Chile |
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| Research Abstract |
We have made a survey of the CO J=2-1 emission from the southern Milky Way and the Large Magellanic Cloud with the dedicated 60-cm survey telescope. A complete L-V map was made for the CO J=2-1/J=1-0 intensity ratio in the inner Galaxy. The Galactic disk exhibits a ratio of 0.3-1.0, with the mean value gradually declining with the galactocentric distance. A high quality data were taken for the Galactic center region. Our analysis revealed that the molecular gas in the central 200 pc of the Galactic center has the pressure an order of magnitude higher than that in the Galactic disk. A method was developed to re-construct a face-on map of the molecular gas in the Galactic center region. It relies on quantitative comparison between the CO emission and OH absorption lines, and is independent from the kinematical models. The face-on map shows a molecular bar with a size of 500 pc by 200 pc. The molecular gas in the Large Magellanic Cloud shows the ratio somewhat higher than that in the Galactic disk. The complex of molecular clouds south of 30 Dor appears to contain a large amount of dense gas without ongoing massive star formation.
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