2014/12/31 by Anjali John Kaithakkal, Y. Suematsu, M. Kubo +3 · 7 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Flow (mathematics) #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Magnetic field #Optical telescope #Photosphere #Polar #Polarity (international relations) #Polarity symbols #Solar and Space Plasma Dynamics #Telescope #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/799/2/139
published in The Astrophysical Journal 799(2), 139 (IOP Publishing) · 13 pages, 21 figures, Accepted for Publication in ApJ
arxiv created 2015/01/03 · openalex publication_date 2015/01/22 · arxiv updated 2015/06/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigated the role of photospheric plasma motions in the formation and evolution of polar magnetic patches using time-sequence observations with high spatial resolution. The observations were obtained with the spectropolarimeter on board the Hinode satellite. From the statistical analysis using 75 magnetic patches, we found that they are surrounded by strong converging, supergranulation associated flows during their apparent lifetime and that the converging flow around the patch boundary is better observed in the Doppler velocity profile in the deeper photosphere. Based on our analysis, we suggest that the like-polarity magnetic fragments in the polar region are advected and clustered by photospheric converging flows, thereby resulting in the formation of polar magnetic patches. Our observations show that, in addition to direct cancellation, magnetic patches decay by fragmentation followed by unipolar disappearance or unipolar disappearance without fragmentation. It is possible that the magnetic patches of existing polarity fragment or diffuse away into smaller elements and eventually cancel out with opposite polarity fragments that reach the polar region around the solar cycle maximum. This could be one of the possible mechanisms by which the existing polarity decays during the reversal of the polar magnetic field.