To be published in the ISO Special Issue of Space
Science Reviews: "ISO science legacy - a compact review of ISO major
achievements", Springer 2005.
For a PDF version of the article, click
For a PDF version of the article, click here.
Abstract. Following on from IRAS, ISO has provided a huge advancement in our knowledge of the phenomenology of the infrared (IR) emission of normal galaxies and the underlying physical processes. Highlights include: the discovery of an extended cold dust emission component, present in all types of gas-rich galaxies and carrying the bulk of the dust luminosity; the definitive characterisation of the spectral energy distribution in the IR, revealing the channels through which stars power the IR light; the derivation of realistic geometries for stars and dust from ISO imaging; the discovery of cold dust associated with HI extending beyond the optical body of galaxies; the remarkable similarity of the near-IR (NIR)/ mid-IR (MIR) SEDs for spiral galaxies, revealing the importance of the photo-dissociation regions in the energy budget for that wavelength range; the importance of the emission from the central regions in shaping up the intensity and the colour of the global MIR luminosity; the discovery of the "hot" NIR continuum emission component of interstellar dust; the predominance of the diffuse cold neutral medium as the origin for the main interstellar cooling line, [CII] 158 µm, in normal galaxies.
Keywords galaxies: spiral, galaxies: dwarf, galaxies: ellipticals, galaxies: ISM
Table of Contents
1 Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA. Back.