MIZUNO Akira Nagoya University, Department of Science, Assistant Professor, 理学部, 助手 (80212231)
OGAWA Hideo Nagoya University, Department of Science, Associate Professor, 理学部, 助教授 (20022717)
|Budget Amount *help
¥38,400,000 (Direct Cost : ¥38,400,000)
Fiscal Year 1994 : ¥5,700,000 (Direct Cost : ¥5,700,000)
Fiscal Year 1993 : ¥32,700,000 (Direct Cost : ¥32,700,000)
We have carried out a large-scale survey with two 4 meter millimeter-wave telescopes, and obtained about 300,000 spectra of ^<13>CO (J=1-0) emission toward the Cygnus, Cassiopeia, Ophiuchus, Serpens and Taurus regions. The observed area corresponds to 15% of the whole sky, which makes this survey the most extensive one among those made in ^<13>CO.We have identified more than 1,000 ^<13>CO clouds and analyzed the physical paramerers of these clouds. Comparing with the IRAS point sources, we have examined the star formation activity of each cloud and the relationship between the characteristics of newly-born stars and those of clouds. This is the first time to analyze characteristics of clouds based on such a uniform spectral data. As a result, following two points are found :
(1) The mass spectrum of clouds is expressed as a power-law with the index-1.7 in the range 100-10,000 M_<<of sun>>.
(2) There is a relationship between the luminosity of the most luminous star within each cloud and the mass of the cloud ; i.e., the maximum stellar luminosity increases with the cloud mass.
We have also found the following three points through the detailed ^<13>CO observations toward Taurus region ; (1) the basic structure of the Taurus cloud is filamentary, (2) star formation has taken place where the column density reaches its highest and (3) soon after the formation occurs, high-density molecular gas disappears. We have studied the dense regions of clouds in detail by observations of C^<18>O,which is more transparent than ^<13>CO,and found that above relations (2) and (3) are more significant than in ^<13>CO.These results are valuable knowledge in order to understand the star formation within molecular gas.