Observations of magnetic field evolution in a solar flare

I±V and I±Q profiles of nine spectral lines of Fei, Feii, and Hi in the 2B flare of 16 June 1989 have been analyzed. Two bright flare knots outside and inside of a spot were investigated. To measure the true magnetic field strength in the flare, two different methods were applied. In addition to these data, the magnetic field and thermodynamic conditions were determined using the non-LTE program for line profile synthesis. According to the measurements, the magnetic field in both flare knots changed in synchronism and non-monotonically, and reached its peak (nearly 1.6 kG for non-spot areas and approximately 4.0 kG for sunspot locations) at the time of flare peak. For the flare knot outside the spot, a background field component was also detected; the magnetic field in this component was found to have mixed polarity and remained practically unchanged during the flare. The non-LTE calculations show that the unique local magnetic field peak existed near the temperature minimum zone in the flare peak too. The observed perturbations do not exclude such phenomena as a magnetic field transient in flare.