Talk abstract details

Michel et al. (2008, Science, 322, 558) measured with CoRoT solar-like oscillations in three stars hotter than the Sun and found the amplitudes of the luminosity fluctuations to be about 25 % below the theoretical values. They attributed this discrepancy to the non-adiabaticity of the process at work in these stellar atmospheres.
Severino and co-workers analyzed the temperature and velocity fluctuations of the Sun by using numerical simulations of compressible convection and demonstrated that the effects of the atmospheric temperature gradient and opacity give important contributions to the observed intensity amplitudes of the solar 5-minute oscillations (Severino, Straus and Steffen: 2008, in Helioseismology, Asteroseismoly and MHD Connection, Gizon et al. eds., p. 547).
Motivated by the results of CoRoT and based on the solar experience, we develop a new stellar scaling law for the intensity-velocity amplitude ratio (gain) of resonant oscillations, which is a quantity independent of the excitation model. The comparison of our approach with observations gives new interesting results for the Sun as a star. Moreover, for the solar-like stars observed by CoRoT, we found that our scaling law provides an explanation of the low observed luminosity amplitudes which is an alternative to non-abiabatic effects.