Self-consistent Simulations of Alfven Wave Driven Winds from the Sun and Stars

TL;DR

This paper reviews self-consistent MHD simulations of Alfven wave-driven winds from the Sun and stars, highlighting wave reflection effects, observational signatures, and stellar evolution impacts on wind properties.

Contribution

It presents new 1D MHD simulation results of solar and stellar winds, emphasizing wave reflection and its role in wind acceleration and structure.

Findings

Wave reflection significantly influences wind acceleration.

Observations may detect Alfvenic wave reflection signatures.

Stellar evolution affects wind properties through gravity and wave reflection.

Abstract

We review our recent results of Alfven wave-driven winds. First, we present the result of a self-consistent 1D MHD simulations for solar winds from the photosphere to interplanetary region. Here, we emphasize the importance of the reflection of Alfven waves in the density stratified corona and solar winds. We also introduce the recent HINODE observation that might detect the reflection signature of transverse (Alfvenic) waves by Fujimura & Tsuneta (2009). Then, we show the results of Alfven wave-driven winds from red giant stars. We explain the change of the atmosphere properties from steady coronal winds to intermittent chromospheric winds and discuss how the wave reflection is affected by the decrease of the surface gravity with stellar evolution. We also discuss similarities and differences of accretion disk winds by MHD turbulence.