Dust temperatures in the Infrared Space Observatory atlas of bright spiral galaxies

We examine far-infrared and submillimeter spectral energy distributions for galaxies in the Infrared Space Observatory Atlas of Bright Spiral Galaxies. For the 71 galaxies where we had complete 60-180 mum data, we fitted blackbodies with lambda(-1) emissivities and average temperatures of 31 K or lambda(-2) emissivities and average temperatures of 22 K. Except for high temperatures determined in some early-type galaxies, the temperatures show no dependence on any galaxy characteristic. For the 60-850 mum range in eight galaxies, we fitted blackbodies with lambda(-1), lambda(-2), and lambda(-beta) (with beta variable) emissivities to the data. The best results were with the lambda(-beta) emissivities, where the temperatures were similar to30 K and the emissivity coefficient beta ranged from 0.9 to 1.9. These results produced gas-to-dust ratios that ranged from 150 to 580, which were consistent with the ratio for the Milky Way and which exhibited relatively little dispersion compared with fits with fixed emissivities.