Gamma rays from nuclear lines are the most-direct astronomical messenger for nucleosynthesis through nuclear reactions in cosmic objects such as stars and stellar explosions (next to neutrinos). Characteristic lines from radioactive decays have been measured with space-borne telescopes, most-recently with ESA’s INTEGRAL mission, for the isotopes 56Ni, 57Ni, 44Ti, 26Al, and 60Fe. These span a half-life range from a few days to millions of years. We have learned about explosive nucleosynthesis and supernova explosion physics (from the shorter-lived species), and about interiors of massive stars and about ejecta transport (from the long-lived ones). Positron annihilation gamma rays have contributed more and independent information on the latter. Other nuclear lines would be expected, e.g. from cosmic-ray interactions, but still are lower in intensity than instrumental sensitivities. In this talk we will discuss the lessons and challenges in context of nucleosynthesis sources and of properties of our Galaxy.
Local contact and organization: Stéphane SCHANNE
