DIAGNOSTICS OF THE EXTERNAL PHYSICAL PROCESSES FROM GLOBAL OSCILLATIONS OF SOLAR-LIKE STARS

摘要

We present and discuss a method to determine the phase shift of the global acoustic oscillations of solar-like stars. This quantity can be used to infer the main contributors of the mechanical behavior of the acoustic waves in the outer layers of the star as far as the energy transport and the photospheric helium abundance are concerned. The phase shift is obtained for the Sun and for a specific candidate, β Virginis (HD 102870), in the perspective of interpreting the next generation of asteroseismology measurements. It is found that the signature of the ionization of helium is better determined in a solar-like star slightly more massive than the Sun and that this analysis can provide a very useful indicator of the photospheric helium content, particularly in clusters. We also find a noticeable sensitivity to the value of the mixing-length parameter.