Numerical aspects of 3D stellar winds

TL;DR

This paper compares numerical methods for simulating 3D stellar winds, including effects of orbiting planets, and provides guidelines for accurate modeling of star-planet interactions.

Contribution

It systematically evaluates different numerical approaches and introduces guidelines for modeling stellar winds with close-in planets using 3D simulations.

Findings

Limit rotation rate of the rotating frame for better accuracy

Comparison shows differences between 3D and 2D simulations

Guidelines improve future 3D stellar wind modeling

Abstract

This paper explores and compares the pitfalls of modelling the three-dimensional wind of a spherical star with a cartesian grid. Several numerical methods are compared, using either uniform and stretched grid or adaptative mesh refinement (AMR). An additional numerical complication is added, when an orbiting planet is considered. In this case a rotating frame is added to the model such that the orbiting planet is at rest in the frame of work. The three-dimensional simulations are systematically compared to an equivalent two-dimensional, axisymmetric simulation. The comparative study presented here suggests to limit the rotation rate of the rotating frame below the rotating frame of the star and provides guidelines for further three-dimensional modelling of stellar winds in the context of close-in star-planet interactions.