Observations of cosmic nuclear gamma-ray lines

Nucleosynthesis in stars and supernovae creates radioactive nuclei, which are ejected into the interstellar medium by stellar winds and explosive events. Their radioactive decay is accompanied by the emission of gamma-ray lines that can be observed by space observatories. Different isotopes are identified and their distribution and kinematics is studied using spectroscopic information. With more than five years of INTEGRAL/SPI observations we can spatially resolve the ²⁶Al emission along the Galactic disk, derive the scale height of the Galactic ²⁶Al distribution and provide constraints on ²⁶Al kinematics for different regions. Groups of massive stars are detected in ²⁶Al and thus can serve as laboratories to study the feedback of the freshly synthesised nuclei into the surrounding interstellar medium. We predict the yields of massive star clusters using population synthesis models. Additionally, INTEGRAL has observed the decay lines of ⁴⁴Ti, constraining the dynamics of ⁴⁴Ti within the Cassiopeia A supernova remnant.