The Origin of p-mode Asymmetry and Asymmetry Reversal in Solar-like Oscillators
Space-borne missions such as Kepler allow us to achieve a spectral resolution which is now sufficiently high to resolve the shape of the p-mode line profiles of solar-like stars, and in particular to measure the asymmetry they feature in the temporal Fourier domain. However, the physical origin of these asymmetries is still not fully understood, even for the Sun. In particular, there is no clear consensus to explain the asymmetry reversal between the velocity and intensity observables.
In this context, I will present an approach designed to better understand the physical origin of solar-like p-mode asymmetries, both in velocity and intensity. To that end, we model the spectral power density by convolving 1) the Green’s function associated to the oscillating mode, which we computed numerically using a 1D evolutionary stellar model, and 2) a source term, obtained by coupling an analytical turbulence model with CO5BOLD 3D simulations of the stellar atmosphere. I will show that we successfully reproduce the observed asymmetries in the case of the Sun, both in velocity and intensity. These results allow us to better understand the physical mechanisms pertaining to solar-like p-modes asymmetry, and go a long way towards explaining the asymmetry reversal puzzle.