26Al in galaxy regions:: massive-star interactions with the ISM

Galactic Al-26 is believed to be predominantly injected into the ISM from winds and supernovae of massive stars. These stars are typically born in groups and associations, which evolve over tens of Myrs, and shape the interstellar medium in their surroundings. Al-26 contained in stellar outflows produces a gamma-ray line at 1.809 MeV, which is potentially observable from regions of active star formation on time scales of a few Myrs, i.e., comparable to the mean life of Al-26. This relatively long time scale may lead to spatial offsets between the observed Al-26 gamma-ray emission and tracers of Al-26 sources, such as locations of massive-stars, HII regions, or IR emission from dust heated by starlight. We find evidence for such an offset in star forming regions towards Orion. (C) 2003 Elsevier B.V. All rights reserved.