DUST IN THE SINGS GALAXY SAMPLE

Dust, models have been applied to interpret the IR emission from 65 galaxies in the SINGS galaxy survey, dust masses, PAH fractions, and starlight intensities to be determined. The dust models reproduce the global SEDs without requiring "cold" (T less than or similar to 12 K) dust. The bulk of the IR emission appears to be radiated by dust in the diffuse ISM, with starlight intensities similar to the intensity in the solar neighborhood. A fraction f(PDR) of the IR emission is radiated by dust in regions of high starlight intensities (e.g., PDRs), with median f(PDR) = 0.08. The dust, composition is characterized by q(PAH); the fraction of the dust mass contributed by PAHs with < 10(3) C atoms. Galaxies with metallicities Z/Z(circle dot) < 0.2 tend to have q(PAH) less than or similar to 0.01, but galaxies with Z/Z(circle dot) > 0.4 have q(PAH) = 0.02 - 0.05. Over the entire sample, with Z/Z(circle dot) ranging from 0.1 to 1, the observations are consistent with a constant function of interstellar metals being in dust, with M(dust)/M(H) approximate to 0.01(Z/Z(circle dot)).