2004A&A...414...69W

We present global IR properties of the Small Magellanic Cloud using an ISOPHOT 170µm map and re-visited IRAS data. The integrated 170µm flux is 14950±2300Jy, and the integrated IR flux is F_1–1000=7.48x10^–10W/m². Discrete sources contribute 28%, 29%, and 36% to the integrated flux at 60µm, 100µm, and 170µm, respectively. Most of the total emission arises from diffuse emission regions surrounding the HII regions. The SED can be modelled by the composition of a 45K, a 20.5K and a 10K blackbody component with emissivity index n=2. A color temperature map is constructed from the ISOPHOT 170µm and the IRAS 100µm HiRes maps. The average dust temperature is T_D=20.3K. The total dust mass is found to be M_D=7.8x10⁵M_☉, yielding a gas-to-dust mass ratio M_gas/M_dust≃540, a value 25 times lower than found by former studies. The global star formation rate is estimated to SFR_total≃0.05M_☉/yr. The comparison with other irregular galaxies reveals the SMC as quiet with no peculiar FIR properties.