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THE CO(J=2-1)/CO(J=1-0) Luminosity Ratio in the Orion Giant Molecular Clouds

Published online by Cambridge University Press:  12 April 2016

Seiichi Sakamoto ,
Tetsuo Hasegawa ,
Masahiko Hayashi ,
Toshihiro Handa  and
Tomoharu Oka
Seiichi Sakamoto
Affiliation:
Department of Astronomy, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Tetsuo Hasegawa
Affiliation:
Institute of Astronomy, University of Tokyo, Mitaka, Tokyo 181, Japan
Masahiko Hayashi
Affiliation:
Department of Astronomy, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Toshihiro Handa
Affiliation:
Institute of Astronomy, University of Tokyo, Mitaka, Tokyo 181, Japan
Tomoharu Oka
Affiliation:
Department of Astronomy, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan

Abstract

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The first results of large-area mapping observations of nearby giant molecular clouds in the CO(J=2-1) emission are presented. The CO(J=2-1)/CO(J=1-0) luminosity ratio is 0.75 and 0.62 for the Orion A and B clouds, respectively. These values are consistent with those observed typically in disks of galaxies (−0.6), and are significantly lower than large values (≳1) often observed in active star-forming regions in galaxies. Active star-forming regions in galaxies cannot be explained by ensemble of Orion-like GMCs; they may contain a different population of molecular clouds with high J-2-1/J=1-0 luminosity ratio.

Type
3. Astronomical Results and Prospects
Information
International Astronomical Union Colloquium , Volume 140: Astronomy with Millimeter and Submillimeter Wave Interferometry , 1994 , pp. 232 - 233
Copyright
Copyright © Astronomical Society of the Pacific 1994

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