Evidence of photospheric vortex flows at supergranular junctions observed by FG/SOT (Hinode)

TL;DR

This study provides evidence of long-lasting vortex flows at supergranular junctions in the quiet Sun's photosphere, observed through granulation tracking with Hinode data, revealing previously uninvestigated large-scale twisting motions.

Contribution

It is the first to identify and characterize long-lived vortex flows at supergranular junctions in the quiet photosphere using high-resolution Hinode observations.

Findings

Vortex flows last at least 1 hour and over 2 hours.

Vortex widths are approximately 15.5 Mm and 21 Mm.

Vortex flows are located at supergranular junctions.

Abstract

Twisting motions of different nature are observed in several layers of the solar atmosphere. Chromospheric sunspot whorls and rotation of sunspots or even higher up in the lower corona sigmoids are examples of the large scale twisted topology of many solar features. Nevertheless, their occurrence at large scale in the quiet photosphere has not been investigated. The present study reveals the existence of vortex flows located at the supergranular junctions of the quiet Sun. We use a 1-hour and a 5-hour time series of the granulation in Blue continuum and G-band images from FG/SOT to derive the photospheric flows. A feature tracking technique called Balltracking is performed to track the granules and reveal the underlying flow fields. In both time series we identify long-lasting vortex flow located at supergranular junctions. The first vortex flow lasts at least 1 hour and is ~20-arcsec-wide (~15.5 Mm). The second vortex flow lasts more than 2 hours and is ~27-arcsec-wide (~21 Mm).