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

• Main Authors: Nagashima, Kaori, Zhao, Junwei, Kosovichev, Alexander G., Sekii, Takashi
• Format: Text
• Language: unknown
• Published: arXiv 2010
• Subjects: Solar and Stellar Astrophysics astro-ph.SR; FOS Physical sciences; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.1011.1025; https://arxiv.org/abs/1011.1025

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. : 7 pages, 5 figures. Accepted for publication in ApJ Letters. Minor modifications in figures and texts