  LUNA, Laboratory for Underground Nuclear Astrophysics at Gran Sasso, is
measuring fusion cross sections down to the energy of the nucleosynthesis
inside stars. Outstanding results obtained up to now are the cross-section
measurements within the Gamow peak of the Sun of $^{3}He(^{3}He,2p)^{4}He$ and
the $D(p,\gamma)^{3}He$. The former plays a big role in the proton-proton
chain, largely affecting the calculated solar neutrino luminosity, whereas the
latter is the reaction that rules the proto-star life during the pre-main
sequence phase. The implications of such measurements will be discussed.
Preliminary results obtained last year on the study of
$^{14}N(p,\gamma)^{15}O$, the slowest reaction of the CNO cycle, will also be
shown.
