Description |
In the local universe, most of the observable matter is contained in stellar objects shaping the morphology and dynamics of their parent galaxy. In view of the dominance of stellar mass, a better understanding of star formation and its consequences is mandatory and forms a central topic of contemporary astrophysical research. There exist a large number of high linear resolution studies related to individual star forming regions of the Galaxy as well as of low linear resolution studies of external galaxies. For a complete view onto the physical and chemical processes driving star formation and galactic evolution it is, however, essential to combine local conditions affecting individual star formation with properties only becoming apparent on global scales.
The optimal target providing such a complete view is a galaxy that is actively forming stars, that is not seen edge-on (like our Galaxy), that has been studied at radio, optical and X-ray wavelengths, and that is sufficiently nearby to also permit studies on small scales. For our carefully chosen template galaxy, we plan to use HIFI to obtain fully-sampled large-scale CII (and H2O) maps. PACS will add important interstellar cooling lines, OI, NII, NIII. And SPIRE & PACS will be used to map the dust spectral energy distribution over the entire galaxy.
Observing a deep, extended strip along the major axis of our template galaxy M33, will allow us to study the ionized, atomic, and molecular phases of the interstellar medium, its life cycle and thermal balance, tracing the formation of molecular clouds and of stars. Aside of insights related to the local processes in the galaxy itself, the mapped source will set a standard, providing a basis for the interpretation of phenomena encountered in other targets of the Local Group and in more distant galaxies. |