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Paper: Turbulent Hydrodynamics and Oscillations of Moderate-Mass Stars
Volume: 479, Progress in Physics of the Sun and Stars
Page: 377
Authors: Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A.
Abstract: The solar-type pulsators are characterized by acoustic oscillation modes excited by turbulent convection in the upper convective boundary layer. As the stellar mass increases the convection zone shrinks, the scale and intensity of the turbulent motions increases, providing more energy for excitation of acoustic modes. When the stellar mass reaches about 1.6 solar masses the upper convection zone consists of two very thin layers corresponding to H and He ionization, and in addition to the acoustic modes the stars show strong internal gravity modes. The thin convection zone is often considered insignificant for the stellar dynamics and variability. We use three-dimensional (3D) numerical radiative hydrodynamics simulations to study convective and oscillation properties of Main Sequence stars from the solar-type stars to more massive stars. We present simulation results for some of the target stars selected for the Kepler Guest Observer project “Transition in Variable Stars: From Solar-Type Stars to Gamma-Doradus Stars.” For the moderate-mass (A-type) stars the simulations reveal supersonic granular-type convection of a scale significantly larger than the solar granulation scale, and strong overshooting plumes penetrating into the stable radiative zone, that can affect the oscillation properties of these stars.
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