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The necessity of finding a signal buried in noise is a common problem in astrophysics where noise limited observations are usually preceding interesting discoveries. In particular we are interested in the detection of p-mode oscillation frequencies of solar-like stars which, at least for the moment, have a very poor S/N ratio. In this work, it is

Velocity measurements of disk integrated sunlight obtained by GOLF experiment aboard SOHO are used to find the parameters of solar p-modes (l

We evaluate the stratification of acoustic oscillations in the solar photosphere in both the Lagrangian (comoving) frame of reference and the Eulerian (inertial) frame of reference, from a temporal sequence of model atmospheres in an optical depth scale obtained after a quasi-non-LTE inversion of the radiative transfer equation applied to spectral

Accurate determination of the rotation rate in the inner radiative zone (0.2 r/Rsolar 0.5) of the sun from helioseismic observations requires rotational frequency splittings of exceptional quality. Indeed, only low degree modes are sensitive to the dynamics of the deep interior. Low and intermediate degree splittings have been estimated from a

This article presents an introduction to optical pumping, atomic polarization and the Hanle effect in weakly magnetized stellar atmospheres. Although the physical processes and the theoretical framework described here are of interest for applications in a variety of astrophysical contexts (e.g. scattering polarization in circumstellar envelopes and