Detection of Supergranulation Alignment in Polar Regions of the Sun by Helioseismology

TL;DR

This study reveals a new alignment pattern of supergranulation cells in the Sun's polar regions using helioseismology, showing systematic north-south alignment and latitudinal size variations.

Contribution

First detection of supergranulation cell alignment in polar regions of the Sun using helioseismology and high-resolution Hinode data.

Findings

Supergranulation cells in polar regions show systematic north-south alignment.

Supergranulation cell size decreases with increasing latitude.

Alignment pattern appears common in polar regions.

Abstract

We report on a new phenomenon of `alignment' of supergranulation cells in the polar regions of the Sun. Recent high-resolution datasets obtained by the Solar Optical Telescope onboard the Hinode satellite enabled us to investigate supergranular structures in high-latitude regions of the Sun. We have carried out a local helioseismology time-distance analysis of the data, and detected acoustic travel-time variations due to the supergranular flows. The supergranulation cells in both the north and south polar regions show systematic alignment patterns in the north-south direction. The south-pole datasets obtained in a month-long Hinode campaign indicate that the supergranulation alignment property may be quite common in the polar regions. We also discuss the latitudinal dependence of the supergranulation cell sizes; the data show that the east-west cell size decreases towards higher latitudes.