THE CII AND 01 EMISSION LINES IN NGC 6946 AND NGC 1313

摘要

The [CII (158 μm)] fine structure line, which is the principal cooling line of the atomic gas, in two nearby galaxies observed with LWS on board ISO is compared to dust and HI gas emission and heating intensity. The relation between photoelectric effect on different grains populations, dust and gas heating found for a sample of 60 normal galaxies for which global [CII] measurements are available, still holds on scale of - 1.5 kpc. We also succeed in detecting cooling from a low density diffuse atomic gas associated with the diffuse optical disk in both galaxies, accounting typically for - 30-40% of the total [CII] emission.