Effects of granulation on the visibility of solar oscillations

Abstract

Context. The interaction of solar oscillations with near surface convection is poorly understood. These interactions are likely the cause of several problems in helio- and astero-seismology, including the so-called surface effect and apparently unphysical travel time shifts as a function of center to limb distance. There is thus a clear need for further theoretical understanding and observational tests. Aims. The aim is to determine how the observed modes are affected by the convection. Methods. I use HMI velocity and intensity images to construct k-$\ddot{I}‰$ diagrams showing how the oscillation amplitude and phase depend on the local granulation intensity. Results. There is a clear and significant dependence of the observed properties of the oscillations on the local convection state.