  The knowledge of stellar evolution is evolving quickly thanks to an increased
number of opportunities to scrutinize the stellar internal plasma properties by
stellar seismology and by 1D and 3D simulations. These new tools help us to
introduce the internal dynamical phenomena in stellar modeling. A proper
inclusion of these processes supposes a real confidence in the microscopic
physics used, partly checked by solar or stellar acoustic modes. In the present
paper we first recall which fundamental physics has been recently verified by
helioseismology. Then we recall that opacity is an important ingredient of the
secular evolution of stars and we point out why it is necessary to measure
absorption coefficients and degrees of ionization in the laboratory for some
well identified astrophysical conditions. We examine two specific experimental
conditions which are accessible to large laser facilities and are suitable to
solve some interesting questions of the stellar community: are the solar
internal radiative interactions properly estimated and what is the proper role
of the opacity in the excitation of the non radial modes in the envelop of the
$\beta$ Cephei and the Be stars ? At the end of the paper we point out the
difficulties of the experimental approach that we need to overcome.
