Nucleosynthesis and gamma-ray lines
  Astrophysical gamma-ray spectroscopy is an invaluable tool for studying nuclear astrophysics, supernova structure, recent star formation in the Milky Way and mixing of nucleosynthesis products in the interstellar medium. After a short, historical, introduction to the field, I present a brief review of the most important current issues. Emphasis is given to radioactivities produced by massive stars and associated supernova explosions, and in particular, those related to observations carried out by INTEGRAL: short-lived Ti-44 from CasA and long-lived Al-26 and Fe-60 from massive stars. The observed 511 keV emission from positron annihilation in the Galaxy and the role of stellar radioactivity and other potential positron sources are also discussed. 
Nikos Prantzos (UPMC and Institut d'Astrophysique de Paris)
astro-ph.HE