Showing papers by "Edwin A. Valentijn published in 1998"

Resolved 200mu M images of nearby galaxies - evidence for an extended distribution of cold dust

Abstract: We present resolved 200µm images for 8 nearby galaxies observed with the Infrared Space Observatory (ISO). By comparing the200µ m observations with IRAS 60µ m and 100µ m data, we find that cold dust becomes more dominant at larger radii. We infer a grain temperature of 18-21 K for this cold component i.e. about 10 K lower than the warm dust detected by IRAS in external spirals. This value is close to theoretical predictions in the literature based on heating by the general interstellar radiation field. A comparison of the200µ m images with complementary B-band data also shows that the cold dust is radially more extensive than the stars. The gas-to-dust ratio of external spirals, derived using IRAS fluxes, has been claimed to be about an order of magnitude higher than the value infered for the Galaxy. By analysing the200µ m data for our sample, we derive a mean gas-to-dust ratio of which is close to the value in the solar neighborhood (150-300). It is likely that IRAS may have `overlooked' the vast majority of grains residing in spiral disks.