Abstract We report results from a multi-wavelength study of the 3B/X1.2 two-ribbon disk flare (S15E44), which was well observed by both ground-based and space-borne instruments. Two pairs of conjugate kernels – K1 and K4, and K2 and K3 – in the Hα images are identified. These kernels are linked by two different systems of EUV loops. K1 and K4 correspond to the two 17 GHz and 34 GHz microwave sources observed by the Nobeyama Radioheliograph (NoRH), while K2 and K3 have no corresponding microwave sources. Optical spectroscopic observations suggest that all the four kernels are possible precipitating sites of non-thermal electrons. Thus the energy of electron deposited in K2 and K3 should be less than 100 keV. Two-dimensional distributions of the full widths at half maximum (FWHM) of the Hα profiles and the line-of-sight (LOS) velocities derived from the Ca II 8542 Å profiles indicate that the largest FWHM and LOS velocity tends to be located near the outer edges of Hα kernels, which is consistent with the scenario of current two-ribbon flare models and previous results. When non-thermal electron bombardment is present, the observed Hα and Ca II 8542 Å profiles are similar to previous observational and theoretical results, while the He I 10830 Å profiles are different from the theoretical ones. This puts some constraints on future theoretical calculation of the He I 10830 Å line.
Keywords Sun: flares --- Sun: X-rays --- line: profiles
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