Role of Longitudinal Waves in Alfven-wave-driven Solar/Stellar Wind

TL;DR

This study demonstrates that p-mode-like oscillations in the photosphere significantly influence solar wind properties by enhancing coronal heating and mass-loss rates through mode conversion processes in the chromosphere.

Contribution

It reveals the crucial role of longitudinal waves and mode conversion in driving and modulating solar and stellar winds, supported by detailed MHD simulations.

Findings

Mass-loss rate increases up to 4 times with higher longitudinal perturbations.

Transverse waves are generated via mode conversion from longitudinal waves.

Enhanced coronal heating leads to higher coronal density and wind acceleration.

Abstract

We study the role the the p-mode-like vertical oscillation on the photosphere in driving solar winds in the framework of Alfven-wave-driven winds. By performing one-dimensional magnetohydrodynamical numerical simulations from the photosphere to the interplanetary space, we discover that the mass-loss rate is raised up to 4 times as the amplitude of longitudinal perturbations at the photosphere increases. When the longitudinal fluctuation is added, transverse waves are generated by the mode conversion from longitudinal waves in the chromosphere, which increases Alfvenic Poynting flux in the corona. As a result, the coronal heating is enhanced to yield higher coronal density by the chromospheric evaporation, leading to the increase of the mass-loss rate. Our findings clearly show the importance of the p-mode oscillation in the photosphere and the mode conversion in the chromosphere in determining the basic properties of the wind from the sun and solar-type stars.