AAS 201st Meeting, January, 2003
Session 112. The ISM: Clouds and Regions
Poster, Thursday, January 9, 2003, 9:20am-4:00pm, Exhibit Hall AB

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[112.06] Variation of z-height of the molecular clouds on the Galactic Plane

Y. Lee (KAO/TRAO), A.A. Stark (Harvard-Smithsonian Center for Astrophysics)

Using the Bell Laboratories Galactic plane in the J=1-0 transition of 13CO, (l, b) = (-5o to 117o, -1o to +1o), and cloud identification code, 13CO clouds have been identified and cataloged as a function of threshold temperature. Distance estimates to the identified clouds have been made with several criteria. Minimum and maximum distances to each identified cloud are determined from a set of all the possible distances of a cloud. Several physical parameters can be determined with distances, such as z-height [D sin (b)], CO luminosity, virial mass and so forth. We select the clouds with a ratio of maximum and minimum of CO luminosities less than 3. The number of selected clouds is 281 out of 1400 identified clouds with 1 K threshold temperature. These clouds are mostly located on the tangential positions in the inner Galaxy, and some are in the Outer Galaxy. It is found that the z-height of lower luminosity clouds (less massive clouds) is systimatically larger than that of high-luminosity clouds (more massive clouds). We claim that this is the first observational evidence of the z-height variation depending on the luminosities (or masses) of molecular clouds on the Galactic plane. Our results could be a basis explaining the formation mechanism of massive clouds, such as giant molecular clouds.

The author(s) of this abstract have provided an email address for comments about the abstract: yulee@trao.re.kr

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