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Paper: Radiative Hydrodynamical Simulations of Granulation in the Sun at Different Stages Along the Evolutionary Track
Volume: 293, 3D Stellar Evolution
Page: 221
Authors: Robinson, F. J.; Demarque, P.; Li, L. H.; Sofia, S.; Kim, Y.-C.; Guenther, D. B.
Abstract: Realistic solar surface simulations in 3 dimensions have been primarily done for the Sun. This is a logical first step as there is much more accurate observational data available for the Sun than for any other star. After reproducing observed characteristics of solar surface convection, we apply our 3D model to the Sun at later evolutionary stages. We find that while the superadiabatic layer (SAL) in the subgiant is similar to the Sun, the red giant has a much broader and lower SAL. The maximum turbulent pressure and maximum turbulent kinetic energy in the giant are almost double that of the other models. The asymmetry between upflow and downflow seems to decrease as the Sun evolves. This will reduce the size of the kinetic energy flux. We find a linear relationship between the depth of the granules and the surface gravity of the model. Extrapolating to log g = -0.5 (estimated surface gravity of Betelgeuse) suggests about 1000 granules would be required to cover the entire surface of Betelgeuse.
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