Letter to the Editor ISOPHOT boosts dust masses in spiral galaxies

We report photometry with ISO between 60 and 200μm of six galaxies. Three of them are active and the extension of their spectra beyond the IRAS bands up to 200μm confirms our previous conception that most of the dust there is warm and has a fairly uniform temperature of ∼30K. In the other three galaxies which are inactive, we detect a very cold component (∼10K and less) that could hitherto at best be surmised. Themost dramatic consequence is a threefold increase in the mass of interstellar material over what one would calculate without the ISO data.