Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet Sun region

TL;DR

This study analyzes small-scale vortex motions in the quiet Sun's photosphere, revealing their spatial distribution, association with downdrafts, and quantifying their occurrence rate using high-resolution solar observations.

Contribution

It provides the first detailed analysis of the spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet Sun region.

Findings

Vortex occurrence rate is approximately 1.4-1.6 x 10^(-3) vortices per Mm^2 per minute.

Vortices are associated with downdrafts and converging horizontal flows.

Sink cores are the final destination of plasma flows in these vortices.

Abstract

High-resolution observations of a quiet Sun internetwork region taken with the Solar 1-m Swedish Telescope in La Palma are analyzed. We determine the location of small-scale vortex motions in the solar photospheric region by computing the horizontal proper motions of small-scale structures on time series of images. These plasma convectively-driven swirl motions are associated to: (1) downdrafts (that have been commonly explained as corresponding to sites where the plasma is cooled down and hence returned to the interior below the visible photospheric level), and (2) horizontal velocity vectors converging into a central point. The sink cores are proved to be the final destination of passive floats tracing plasma flows towards the center of each vortex. We establish the occurrence of these events to be 1.4 x 10^(-3) and 1.6 x 10^(-3) vortices Mm^(-2) min^(-1) respectively for two time series analyzed here.