Seismic study of solar convection and overshooting: results of nonlocal convection

Local mixing-length theory is incapable of describing nonlocal phenomena in stellar convection, such as overshooting. Therefore standard solar models constructed with the local mixing-length theory deviate significantly from the Sun at the boundaries of the convection zone, where convection becomes less efficient and nonlocal effects are important. The differences between observed and computed frequencies come mainly from the near-surface region, while the localized sound-speed difference is just below the convective envelope. In this paper we compute a solar envelope model using Xiong's nonlocal convection theory, and carry out helioseismic analysis. The nonlocal model has a smooth transition at the base of the convection zone, as revealed by helioseismology. It reproduces solar frequencies more accurately, and reduces the localized sound-speed difference between the Sun and standard solar models.