Premium
A magnetic neutral sheet as cause of the flare productivity of a δ sunspot group
Author(s) -
Seehafer N.
Publication year - 1985
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.2113060405
Subject(s) - sunspot , physics , flare , current sheet , penumbra , magnetic flux , astrophysics , magnetic field , solar flare , satellite , polarity symbols , astronomy , magnetohydrodynamics , medicine , ischemia , quantum mechanics , cardiology , breakdown voltage , voltage
Flare observations in the solar activity complex HR 16862, 16863, 16864 at the end of May 1980 are compared with the structure of force‐free magnetic fields calculated from photospheric magnetograph measurements. A series of homologous flares connected with a δ configuration in HR 16864 was possibly caused by a magnetic neutral sheet. The δ configuration consisted of the large preceding spot of HR 16864 and a small satellite of opposite polarity. All magnetic flux from the satellite is connected to the main spot, and at the outer edge of the satellite, away from the main spot, a magnetic neutral sheet is found. This agrees with the observation that all penumbra was situated between parent spot and satellite, which is typical of such † configurations. It is suggested that the flare productivity of these configurations is generally caused by magnetic neutral sheets at the penumbra‐free outer boundary of the satellites.