New world of Nuclear Gamma-ray Astrophysics opened with near future X-ray missions

New eyes in the hard X-ray to soft gamma-ray band with extremely high sensitivities and energy resolution in future missions, including NeXT satellite, will lead us to a new world of nuclear astrophysics; from elements to nuclear species, and from stable nucleus to unstable ones. One exciting topic is to search for an evidence of the "r-process" nucleosynthesis in the universe. The r-process is the only one process to explain nucleosynthesis of heavier elements than Bi. It occurs only in a explosive neutron-rich environment, like a final stage of supernovae. It is feasible to find some evidence from young supernova remnants by high sensitive search on gamma-ray line emissions from unstable nuclear species produced only by r-process with SGD and HXI on-board NeXT satellite. In this presentation, we will introduce topics on nuclear astrophysics (r-process, 56Ni lines from type Ia supernova, 44Ti lines from abstract