Simulation of photosphere and chromosphere of two powerful solar flares (October 28, 2003 and September 1, 1990) |
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| Authors: | E A Baranovsky V G Lozitsky V P Tarashchuk |
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| Institution: | 1.Crimean Astrophysical Observatory Research Institute,Nauchnyi, Crimea,Ukraine;2.Astronomical Observatory,Taras Shevchenko Kyiv National University,Kyiv,Ukraine |
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| Abstract: | The spectra of two powerful flares with approximately the same intensities in the optical region but with different spectral
features and power in other regions are studied. One of them is the unique flare which occurred on October 28, 2003, importance
X17.2/4B, ranking third in magnitude among the recorded flares. Another occurred on September 1, 1990, 3B importance. The
flares vary in the Balmer decrement. The flare of October 28, 2003, has a ratio of I(Hβ)/I(Hα) = 1.47. This is the largest value for solar flares ever observed. The flares also differ in magnitude of the D Na I lines emission: the emission of the flare of October 28, 2003, is substantially larger than that of the other flare.
The chromosphere models of the flares are computed using the observed profiles of Balmer lines and D Na I lines. The satisfactory agreement of the calculated and observed profiles is obtained for the two-component models in
which a hot component occupies 6% of the area. The hot component of the chromosphere model is characterized with the dense
condensation available in the upper layers. For the flare of October 28, 2003, this condensation is located deeper and its
substance concentration is greater than that for another flare. The Hα line intensity for the model hot component alone is approximately 30 and the continuous spectrum intensity is approximately
3% of the undisturbed level. The photosphere model is computed using the observed profiles of photosphere lines for the flare
of October 28, 2003. It is found that very broad profiles of individual sigma-components of the Fe I λ 525.0 nm line may be
only explained by the presence of magnetic fields having different directions. A great difference is detected between values
of the magnetic field strength obtained in the splitting of sigma-components and those provided by simulation. |
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