The molecular cloud associated with the H II region S301 has been mapped in the J = 1-0 transitions of 12CO and 13CO using the 13.7 m radio telescope of Taeduk Radio Astronomy Observatory. The cloud is elongated along the north-south direction with two strong emission components facing the H II region. Its total mass is 8.7 × 10 3 M⊙. We find a velocity gradient of the molecular gas near the interface with the optical H II region, which may be a signature of interaction between the molecular cloud and the H II region. Spectra of CO, CS, and HCO+ exhibit line splitting even in the densest part of the cloud and suggests the clumpy structure. The radio continuum maps show that the ionzed gas is distributed with some asymmetry and the eastern part of the H II region is obscured by the molecular cloud. We propose that the S301 H II region is at the late stage of the champagne phase, but the second generation of stars has not yet been formed in the postshock layer.

• JAE HOON JUNG(Korea Astronomy Observatory)
• JUNG-Kyu LEE(Department of Astronomy and Atmospheric Sciences, Kyungpook National University/School of Physics, University of New South Wales)
• TAE SEOG YOON(Department of Astronomy and Atmospheric Sciences, Kyungpook National University)
• YONG HEE KANG(Department of Earth Science Education, Kyungpook National University)