2009/10/20 by P. Venkatakrishnan, Sanjiv K. Tiwari, Sanjiv Kumar Tiwari · 40 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Azimuth #Magnetic field #Optics #Photosphere #Physics #Polarimeter #Polarimetry #Solar and Space Plasma Dynamics #Solar telescope #Stellar, planetary, and galactic studies #Sunspot #Telescope #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/706/1/l114
published in The Astrophysical Journal 706(1), L114-L119 (IOP Publishing) · 15 pages, 4 figures, 1 table; accepted for publication in the ApJ Letters
arxiv created 2009/10/20 · openalex publication_date 2009/11/02 · arxiv updated 2014/11/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Various theoretical and observational results have been reported regarding the presence/absence of net electric currents in the sunspots. The limited spatial resolution of the earlier observations perhaps obscured the conclusions. We have analyzed 12 sunspots observed from Hinode (Solar Optical Telescope/Spectro-polarimeter) to clarify the issue. The azimuthal and radial components of magnetic fields and currents have been derived. The azimuthal component of the magnetic field of sunspots is found to vary in sign with azimuth. The radial component of the field also varies in magnitude with azimuth. While the latter pattern is a confirmation of the interlocking combed structure of penumbral filaments, the former pattern shows that the penumbra is made up of a "curly interlocking combed" magnetic field. The azimuthally averaged azimuthal component is seen to decline much faster than 1/ϖ in the penumbra, after an initial increase in the umbra, for all the spots studied. This confirms the confinement of magnetic fields and absence of a net current for sunspots as postulated by Parker. The existence of a global twist for a sunspot even in the absence of a net current is consistent with a fibril-bundle structure of the sunspot magnetic fields.