Abstract:
The mid-infrared spectra (2.5-5 and 5.7-11.6 mu m) obtained by ISOPHOT reveal the interstellar medium emission from galaxies powered by star formation to be strongly dominated by the aromatic features at 6.2, 7.7, 8.6, and 11.3 mu m. Additional emission appears in between the features, and an underlying continuum is clearly evident at 3-5 mu m. This continuum would contribute about a third of the luminosity in the 3-13 mu m range. The features together carry 5%-30% of the 40-120 mu m. range.FIR) luminosity.