ISOPHOT BOOSTS DUST MASSES IN SPIRAL GALAXIES

We report photometry with ISO between 60 and 200 mu m of six galaxies. Three of them are active and the extension of their spectra beyond th e IRAS bands up to 200 mu m confirms our previous conception that most of the dust there is warm and has a fairly uniform temperature of sim ilar to 30 K. In the other three galaxies which are inactive, we detec t a very cold component (similar to 10 K and less) that could hitherto at best be surmised. The most dramatic consequence is a threefold inc rease in the mass of interstellar material over what one would calcula te without the ISO data.