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 240 micrometer are derived to be 15.4+-1.5 K and 9.0+-5.7*10E-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.
Journal of Korean Astronomical Society
- Pub Date:
- April 1997
- INFRARED RADIATION;
- MOLECULAR CLOUDS: GS234-02