Properties of Turbulent Convection and Large-scale Flows in a Rotating F-type Star Revealed by 3D Realistic Radiative Hydrodynamic Simulations

The nonlinear coupling between stellar convection and rotation is of great interest because it relates to understanding both stellar evolution and activity. We investigate the influence of rotation and the Coriolis force on the dynamics and thermodynamic structure of an F-type main-sequence star with a shallow outer convection zone. We perform a series of 3D radiative hydrodynamic simulations of a 1.47M_⊙ star for different rotation rates (periods of rotation 1 and 14 days) and with local computational domains (102.4 Mm × 102.4 Mm × 50.6 Mm) placed at latitudes of 0° (equator), 30°, and 60^°, using the f-plane approximation. Because the star has a relatively shallow convection zone (28.5 Mm thick or about 3% R_*), we model its dynamics from the upper layers of the radiative zone, the whole convection zone, and the low atmosphere. The initial simulation results indicate that rotation suppresses temperature and density perturbations in the upper convection zone, leading to a decrease in the mean temperature throughout the convection zone. In addition to the multiscale granular-type convection, the simulations reveal the formation of roll-like patterns, the circulation in which is responsible for the retrograde flows extending from the photosphere to the bottom of the convection zone, where the mean flows transition to prograde motions with the onset of solid body rotation in the radiative zone, forming the tachocline in the overshooting layer. In this paper, we primarily discuss the properties of the outer convection zone for different rotation rates. A detailed analysis of the properties of the tachocline, the overshoot layer, as well as the properties of acoustic and gravity waves, will be discussed in follow-up papers.