1. M1.0 flare of 22 Oct 2002 RHESSI observations of the M 1.0 solar flare on 22 October 2002 A. Berlicki 1,2, B. Schmieder 1, N. Vilmer 1, G. Aulanier 1 1) Observatoire de Paris, Section de Meudon, LESIA, FRANCE 2) Astronomical Institute of the Wrocław University, POLAND

2. M1.0 flare of 22 Oct 2002 The aim of the work: Why the flare emission in cool chomospheric lines (H, Ca lines) is observed for a long time during the late phase of solar flares ? What kind of heating mechanism is effective during the gradual phase of solar flares ? * Small flux of non-thermal electrons ? * Thermal conduction ? * Radiative heating by soft X-rays ? We try to explain if the non-thermal component in X-ray emission could be present during the gradual phase of solar flares.

3. M1.0 flare of 22 Oct 2002 MDI - cont. BBSO - H-alpha

4. M1.0 flare of 22 Oct 2002 I CONT (Na D1,THEMIS) B LONG (NaD1, THEMIS) HXR (RHESSI) 22 oct 2002 TRACE 195 ang. H  flare (VTT) + RHESSI

5. M1.0 flare of 22 Oct 2002

6. Thermal + non-thermal + Fe/Ni line complex (6.7 & 8 keV)

7. M1.0 flare of 22 Oct 2002

8. Thermal and non-thermal component during the gradual phase a) Thermal energy of plasma: b) Energy contained in the non-thermal electrons (thin target model): (Hudson et al. 1978, Sol. Phys. 60, 137) (for E CUT-OFF = 10 keV)  - power-law index B(x,y) – beta function  10 – X-ray flux at 10 keV [photons cm -2 s -1 keV -1 ]

9. M1.0 flare of 22 Oct 2002 Thermal E th and non-thermal E nth energy contained in the flare of October 22, 2002. ? ? ?

10. M1.0 flare of 22 Oct 2002 Conclusions: 1) During the analysed period the thermal energy is dominant, 2) Non-thermal component provide a marginal input to the total energy but it is necessary to explain the spectra between 10 and 20 keV, ? ? ? * Thin or thick target, * Distinguish between thermal and non-thermal emission at low energies, * Relation between E cut-off and the energy contained in non-thermal electrons – very sensitive !