Systematics of $\alpha$--nucleus optical potentials

Double--folded optical $\alpha$--nucleus potentials can be used to calculate elastic scattering cross sections in a wide mass-- and energy region. Because of the systematic behavior of the potential parameters we are able to obtain reliable optical potentials for astrophysically relevant reactions even without scattering data in low--energy region. As example we analyze the capture reaction ${^{144}{\rm Sm}}(\alpha,\gamma){^{148}{\Gd}}$.