Simulated Coronal Mass Ejections on a young Solar-Type Star and the Associated Instantaneous Angular Momentum Loss

TL;DR

This study uses 3D magnetohydrodynamic simulations to analyze how coronal mass ejections on a young, active solar-type star influence its angular momentum loss, revealing that CMEs can both add and remove angular momentum depending on their energy and mass.

Contribution

It presents the first detailed 3D simulations of stellar CMEs on a young solar-type star, linking CME properties to angular momentum transfer.

Findings

Simulated CMEs are more massive and energetic than solar CMEs.

CME mass ranges from ~10^16 g to ~10^18 g, energies from ~10^31 erg to ~10^33 erg.

Angular momentum can be both gained and lost during CME events, with higher energy/mass CMEs more likely to add angular momentum.

Abstract

Coronal mass ejections (CMEs) on stars can change the stars' magnetic field configurations and mass loss rates during the eruption and propagation and therefore, may affect the stars' rotation properties on long time-scales. The dynamics of stellar CMEs and their influence on the stellar angular momentum loss rate are not yet well understood. In order to start investigating these CME-related aspects on other stars, we conducted a series of magnetohydrodynamic simulations of CMEs on a solar-type star of moderate activity levels. The propagation and evolution of the CMEs were traced in the three-dimensional outputs and the temporal evolution of their dynamic properties (such as masses, velocities, and kinetic energies) were determined. The simulated stellar CMEs are more massive and energetic than their solar analog, which is a result of the stronger magnetic field on the surface of the simulated star than that of the Sun. The simulated CMEs display masses ranging from ~10^16 g to ~10^18 g and kinetic energies from ~10^31 erg to ~10^33 erg. We also investigated the instantaneous influence of the CMEs to the star's angular momentum loss rate. Our results suggest that angular momentum can either be added to or be removed from the star during the evolution of CME events. We found a positive correlation between the amplitude of the angular momentum loss rate variation and the CME's kinetic energy as well as mass, suggesting that more energetic/massive CMEs have higher possibility to add angular momentum to the star.