• Journal of the Korean earth science society
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• v.32 no.4
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• pp.402-410
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• 2011

We present results of CO observations toward an infrared (IR) source, IRAS 07280-1829, and its possibly related molecular clouds. The physical parameters of this IR source such as its infrared slope (${\alpha}$=16) of the Spectral Energy Distribution and bolometric temperature (145 K) indicate that it is an embedded protostar. Its luminosity is ${\sim}2.9{\times}10^4L_{\odot}$, typical of a massive star. The CO profile toward IRAS 07280-1829 has broad wing components, implying a possible existence of CO outflow. The excitation temperature and mass of a molecular cloud (Cloud A) which is thought to harbor the IR source are estimated to be 9~22 K and ~180 $M_{\odot}$, respectively, indicating the Cloud A is a typical infrared-dark cloud. Its LTE mass is found to be much smaller than its virial mass by more than a factor of 10 which is inconsistent with the fact that a protostar recently formed exists in the Cloud A. This may suggest that the environment of the cloud where the IR source is forming is dominant of turbulence and/or magnetic filed, making its virial mass estimated unusually high.