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

TL;DR

This study uses 3D radiative hydrodynamic simulations to explore how rotation influences the convection and large-scale flows in an F-type star, revealing effects like differential rotation, meridional flows, and gravity darkening.

Contribution

First detailed 3D simulations of an F-type star's convection zone incorporating rotation effects, showing new insights into stellar dynamics and structure.

Findings

Rotation causes a shift in ionization zones towards the photosphere.

Differential rotation and meridional flows are formed due to rotation.

Gravity darkening effects are observed in the simulations.

Abstract

The nonlinear coupling between stellar convection and rotation is of great interest because it relates to understanding both stellar evolution and activity. We investigated 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 performed a series of 3D radiative hydrodynamic simulations of a 1.47Msun star for different rotation rates (periods of rotation 1 and 14 days) and with computational domains placed at latitudes of 0degrees (equator), 30degrees, and 60degrees. Because the star has a relatively shallow convection zone (28.5 Mm thick or about 2.81% R*), we model its dynamics from the upper layers of the radiative zone, the whole convection zone, and the low atmosphere. The simulation results show a weak shift of the ionization zones to the photosphere and a decrease of the stellar radius by about 29 km at the equator and about 58 km at higher latitudes in the presence of rotation with a period of 1 day. The models presented reveal the formation of radial differential rotation, meridional flows, latitude-dependent roll-like structures of convection, a tachocline, the presence of a gravity-darkening effect, and others. In this paper, we primarily discuss the properties of the outer convection zone for different rotation rates. Detailed analysis of the properties of the tachocline, the overshoot layer, and small-scale turbulence will be discussed in follow-on papers.