0495019 20240103220714.120181023235959.9 85044724208 000428422500001 10.1051/0004-6361/201732528 13 s. E cav_un_epca*02562060004-6361611EDP Sciences Sun magnetic fields photosphere cav_un_auth*0100034 Jurčák Jan Sluneční oddělení Department of Solar Physics ASU-R Department of Solar Physics - Team 1 A Astronomický ústav AV ČR, v. v. i. cav_un_auth*0313291 Rezaei R. DE cav_un_auth*0287659 Bello González N. ES cav_un_auth*0313290 Schlichenmaier R. DE cav_un_auth*0101228 Vomlel Jiří Matematická teorie rozhodování Department of Decision Making Theory MTR MTR UTIA-B Department of Decision Making Theory Ústav teorie informace a automatizace AV ČR, v. v. i. We aim at studying the magnetic nature of umbra-penumbra boundaries in sunspots of different sizes, morphologies, evolutionary stages, and phases of the solar cycle. We statistically prove that the umbra-penumbra boundary in stable sunspots is characterised by an invariant value of the vertical magnetic field component: the vertical component of the magnetic field strength does not depend on the umbra size, its morphology, and phase of the solar cycle. With the statistical Bayesian inference, we find that the strength of the vertical magnetic field component is, with a likelihood of 99%, in the range of 1849-1885 G with the most probable value of 1867 G. In contrast, the magnetic field strength and inclination averaged along individual boundaries are found to be dependent on the umbral size: the larger the umbra, the stronger and more horizontal the magnetic field at its boundary. BN 10000 10300 10308 2019 UTIA-B 10000 10200 10201 UTIA-B JD RVO:67985815 RVO:67985556 http://hdl.handle.net/11104/0288058 1 S L4 2 Article Astronomy Astrophysics ASTRONOMY&ASTROPHYSICS 5.379 1.922 7.2 0.20466 1.735 131500 2.527 4.570 1902 Q1 86.53 86.2 Q1 Q2 1.21 Q1 86.232 2018 85044724208 SCOPUS PUBMED 000428422500001 WOS cav_un_epca*0256206 Astronomy & Astrophysics 0004-6361 1432-0746 Roč. 611 March 2018 EDP Sciences