Cold Dust in Galaxies

We present 350-1100 micron continuum observations of the central regions of 11 spiral galaxies. Combining our submillimeter fluxes with IRAS data, we find that the 60-1100 micron energy distributions of these galaxies can be well fitted by thermal emission from dust at a single temperature (T ~ 30-50 K). We find no direct evidence for the cold (T <~ 20 K) dust expected if dust is being heated by the interstellar radiation field of a normal galaxy. Furthermore, we show that if this dust does exist, its emission at λ < 100 microns should be negligible. Our estimates of the total mass of interstellar matter in these galaxies are lower than those estimated from CO 1-0 line measurements.