Modelling Radioactivities and other Observables from OB Associations
  Recent observations of the diffuse Galactic gamma-ray glow at 1.809 MeV, attributed to the radioactive decay of 26Al, point towards a massive star origin of this radioactive isotope. Wolf Rayet stars and core-collapse supernovae appear to dominate the production of this isotope. Massive stars are commonly located in clusters and OB associations, regions of recent star formation. We thus discuss the temporal evolution of 26Al, and 60Fe within evolving OB associations. The goal of this study is to utilize the associated gamma-ray lines as a diagnostic tool for the study of correlated star formation, and also to provide more detailed models for the interpretation of data obtained with COMPTEL on the Compton Observatory. We investigate the effects of possible aluminum yield enhancements, predicted for some massive close binary systems. In addition to the ejection of chemically processed matter, massive stars also drive strong stellar winds and emit large fluxes of ionizing radiation. This energy and radiation input into the interstellar medium (ISM) is crucial for the dynamical evolution of the gas and subsequent star forming activity in the galactic disk. We discuss population synthesis models for a variety of star formation histories, and compare the predicted gamma-ray line lightcurves to COMPTEL measurements in the Cygnus region. Radioactive tracers such as 26Al and 60Fe provide a unique gamma-ray tracer of Galactic star formation activity, complementary to other methods using spectral information in the radio, IR or optical bands. 
S.Plueschke, R.Diehl, D.H.Hartmann and U.G.Oberlack