Excitation of acoustic waves by vortices in the quiet Sun

TL;DR

This study uses 3D radiative hydrodynamic simulations to show that vortex tubes in the quiet Sun's intergranular lanes excite acoustic waves through vortex interactions and annihilations.

Contribution

It provides the first detailed simulation-based analysis linking vortex dynamics to acoustic wave excitation in the quiet Sun.

Findings

Vortex tubes are associated with acoustic wave excitation.

High-speed whirlpools can attract and capture other vortices.

Vortex interactions, including annihilation, generate acoustic waves.

Abstract

Five-minutes oscillations is one of the basic properties of solar convection. Observations show mixture of a large number of acoustic wave fronts propagating from their sources. We investigate the process of acoustic waves excitation from the point of view of individual events, by using realistic 3D radiative hydrodynamic simulation of the quiet Sun. The results show that the excitation events are related to dynamics vortex tubes (or swirls) in the intergranular lanes. These whirlpool-like flows are characterized by very strong horizontal velocities (7 - 11 km/s) and downflows (~ 7 km/s), and are accompanied by strong decreases of the temperature, density and pressure at the surface and in a ~ 0.5-1 Mm deep layer below the surface. High-speed whirlpool flows can attract and capture other vortices. According to our simulation results, the processes of the vortex interaction, such as vortex annihilation, can cause the excitation of acoustic waves.