The Far‐Infrared Energy Distributions of Seyfert and Starburst Galaxies in the Local Universe:Infrared Space ObservatoryPhotometry of the 12 Micron Active Galaxy Sample

New far-infrared photometry with ISOPHOT, onboard the Infrared SpaceObservatory, is presented for 58 galaxies with homogeneous published data foranother 32 galaxies all belonging to the 12 micron galaxy sample. In total 29Seyfert 1's, 35 Seyfert 2's and 12 starburst galaxies, about half of the 12micron active galaxy sample, plus 14 normal galaxies for comparison. The ISOand the IRAS data are used to define color-color diagrams and spectral energydistributions (SED). Thermal dust emission at two temperatures (one cold at15-30K and one warm at 50-70K) can fit the 60-200 micron SED, with a dustemissivity law proportional to the inverse square of the wavelength. Seyfert1's and Seyfert 2's are indistinguishable longward of 100 micron, while, asalready seen by IRAS, the former have flatter SEDs shortward of 60 micron. Amild anti-correlation is found between the [200 - 100] color and the "60 micronexcess". We infer that this is due to the fact that galaxies with a strongstarburst component, and thus a strong 60 micron flux, have a steeperfar-infrared turnover. In non-Seyfert galaxies, increasing the luminositycorresponds to increasing the star formation rate, that enhances the 25 and 60micron emission. This shifts the peak emission from around 150 micron in themost quiescent spirals to shorter than 60 micron in the strongest starburstgalaxies.