Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 56, p. 47-51 (2017)

Comparison of chromospheric and photospheric magnetic fields in two solar flares of X1.1/4N and X17.2/4B importance

V.Lozitsky, DrSci
N. Lozitska, PhD

Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv


We compare the specral-polarized obsevations of magnetic fields in two powerful solar flares of October 28, 2003 (of X17.2 / 4B class) and  July 17, 2004 (of X1.1 / 2N class) using FeI and D1 NaI lines. We found that in both flares the effective magnetic field Beff was stronger in the chromosphere than in the photosphere. The strongest magnetic field (4600 Gs) was measured at the chromospheric level of a weaker flare, andthis field was 1.6 times stronger than the magnetic field in the nearest sunspot. Comparing the obtained results with similar data by Lozitska et al [8] forflaresof 1981 and 1989 (i.e., for cycles Nos. 21 and 22), we can see a significant difference. In both flares of 2003 and 2004, which relate to 23rd cycle of solar activity, wehaveBeff (FeI) <Beff(D1) for splitting of emission peaks, whereas for flares of cycles Nos. 21 and 22, the inverse in equality Beff (FeI)>Beff(D1) istrue. This result is still unclear and requires additional scrutiny on a base of new observational data.

Key words
Sun, solar magnetic fields, solar flares of X class, the Echelle Zeeman-spectrograms, splitting of emission peaks, magnetic field strength in photosphere and chromosphere

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DOI: https://doi.org/10.17721/BTSNUA.2017.56.4751