We have studied the IR properties of molecular clouds in the region of the supershell GS234-02 using IRAS and COBE data. The mean values of dust color temperature and optical depth at 240μm are derived to be 15.4±1.5 K and 9.0±5.7×10-4, respectively, which agree well with those determined by Sodroski et al.(1994) for the outer Galaxy. Mean IRAS colors, R12/100= 0.074, R25/100= 0.052, R60/100= 0.219, indicate that the abundance of PAHs is enhanced but other particles are nearly the same as those of the solar neighborhood. We found the anticorrelation between R100/140 and R140/240. It cannot be explained by the thermal emission of traditional big grains. The anticorrelation implies that, at high ISRF, T100/140 underestimates the equilibrium temperature, while T140/240 overestimates it and, at low ISRF, vice versa. Therefore we propose to use the intensity ratio, R100/240 as a dust thermometer.

• JUNG JAE HOON(Korea Astronomy Observatory)
• LEE JUNG KYU(Department of Astronomy and Atmospheric Sciences, Kyungpook National University)
• YOON TAE SEOG(Department of Astronomy and Atmospheric Sciences, Kyungpook National University)