ОСЛАБЛЕННЯ МАГНІТНОГО ПОЛЯ В ГЛИБОКИХ ШАРАХ СОНЯЧНОЇ ПЛЯМИ

The preliminary results of spectralpolarization observations of a large sunspot on August 17, 2024, observed on the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv are presented. Direct measurements of the magnetic field in this spot were performed by splitting the bisectors of the profiles of ten spectral lines, mainly the Fe I lines, as well as three lines of Fe II, Cr II, and Sc II ions. The magnetic field, measured by splitting the sigma components of the Fe I 5250.2 line, reached 3400 G, however, the field magnitude by other lines with smaller Landé factors was significantly smaller, apparently reflecting the longitudinal component BLOS of the magnetic field, rather than its intensity modulus. The shape of the bisectors of the I ± V profiles generally corresponds to a homogeneous field only for the Fe I lines, while for the ion lines these bisectors have a rather peculiar appearance, with a minimum splitting at approximately half the depth of the profiles and a maximum in the core of such lines or in their wings. If the magnetic field averaged over the entire profile is determined based on the average splitting of the bisectors at different depths of each spectral line, the following main effects are revealed: (a) the ion lines show 300–1200 G weaker magnetic fields than the neutral atom lines, (b) the measured BLOS value increases with the Landé factor for the neutral atom lines, but for ions, the corresponding dependence is obviously the opposite, (c) for the neutral atom lines the BLOS value decreases with increasing excitation potential EP of the lower term of the line. Effect (b) for the neutral atoms can be explained by the significant inclination of the field lines to the line of sight, while effects (a) and (c) indicate that the magnetic field strength in the spot decreased with depth. However, it remains unclear what role thermodynamic effects and the subtelescopic structure of the magnetic field might play here.