  State-of-the-art one-dimensional (1D) stellar evolution codes rely on
simplifying assumptions, such as mixing length theory, in order to describe
superadiabatic convection. As a result, 1D stellar structure models do not
correctly recover the surface layers of the Sun and other stars with convective
envelopes. We present a method that overcomes this structural drawback by
employing three-dimensional (3D) hydrodynamic simulations of stellar envelopes:
at every time-step of the evolution interpolated 3D envelopes are appended to
the 1D structure and are used to supply realistic boundary conditions for the
stellar interior. In contrast to previous attempts, our method includes mean 3D
turbulent pressure. We apply our method to model the present Sun. The
structural shortcomings of standard stellar models lead to systematic errors in
the stellar oscillation frequencies inferred from the model. We show that our
method fully corrects for this error. Furthermore, we show that our realistic
treatment of superadiabatic convection alters the predicted evolution of the
Sun. Our results hence have important implications for the characterization of
stars. This has ramifications for neighbouring fields, such as exoplanet
research and galactic archaeology, for which accurate stellar models play a key
role.
