jeudi 31 janvier 2019, par Joten Okamoto (NAOJ, Japan)
Mardi 26 fĂ©vrier 2019 à 11h00 , Lieu : Salle de rĂ©union du bâtiment 14
Sunspots are concentrations of magnetic fields on the solar surface. Then, where is the strongest field in each sunspot ? It is generally located in an umbra, but sometimes stronger fields are found outside umbrae, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Now we have numerous high-quality datasets taken with the Hinode/Spectro-Polarimeter over 10 years, which motivate us to address this question via a statistical analysis of strongest fields in sunspots. Hence, we complied a ranking list of active regions by their largest field strengths and investigated conditions for appearance or formation of strong magnetic fields. In this seminar, we will introduce a sunspot with a field strength of 6250 G as a case study, and then discuss the key features to produce strong fields in a statistical sample.
