PION: Simulations of Wind-Blown Nebulae

TL;DR

This paper introduces PION, an open-source simulation tool for modeling asymmetric wind-blown nebulae around massive stars using radiation-magnetohydrodynamics, with improved parallel performance and 3D simulation results.

Contribution

The paper presents PION, a new open-source software for 3D radiation-magnetohydrodynamics simulations of nebulae, including a hybrid parallel algorithm and application to Wolf-Rayet star nebulae.

Findings

Enhanced scaling with hybrid OpenMP/MPI algorithms.

Simulated nebula evolution matches observed X-ray brightness.

First 3D simulations of Wolf-Rayet star nebulae with detailed analysis.

Abstract

We present an overview of PION, an open-source software project for solving radiation-magnetohydrodynamics equations on a nested grid, aimed at modelling asymmetric nebulae around massive stars. A new implementation of hybrid OpenMP/MPI parallel algorithms is briefly introduced, and improved scaling is demonstrated compared with the current release version. Three-dimensional simulations of an expanding nebula around a Wolf-Rayet star are then presented and analysed, similar to previous 2D simulations in the literature. The evolution of the emission measure of the gas and the X-ray surface brightness are calculated as a function of time, and some qualitative comparison with observations is made.