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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
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
Copyright
Copyright © Astronomical Society of the Pacific 1994

References

Bronfman, L., Cohen, R.S., Alvarez, H., May, J., & Thaddeus, P., 1988, ApJ, 324, 248 Google Scholar
Casoli, F., 1991, in IAU Symposium 146, Dynamics of Galaxies and Their Molecular Cloud Distribuiions, ed. Combes, F., & Casoli, F., (Dordrecht: Kluwer), 51 Google Scholar
Eckart, A., Dowries, D., Genzel, R., Hams, A.I., Jaffe, D.T., & Wild, W., 1990, ApJ, 348, 434 Google Scholar
Loiseau, N.. Nakai, N.. Sofue, Y., Wielebinski, R., Reuter, H.-P., & Klein, U.. 1990, A&A, 228, 331 Google Scholar
Maddalena, R.J., Morris, M., Moscowitz, J., & Thaddeus, P., 1986, ApJ, 303, 375 Google Scholar
Oka, T., Hasegawa, T., Hayashi, M., Handa, T., & Sakamoto, S., 1993. this conferenceGoogle Scholar
Sakamoto, S., Hasegawa, T., Hayashi, M., Handa, T., & Oka, T., 1992, in preparationGoogle Scholar
Turner, J., 1993, this conferenceGoogle Scholar