ИСТИНА

The X -ray emission of very weak flares was registered with the Suzaku/WAM (Endo et al., PASJ, 2010) in 2005–2009. The photon power spectrum in the 50–110 keV range for some B–C3 class flares shows that electrons accelerate to energies higher than 100 keV. Such events are developed very close to solar spots. Effective acceleration in large flares takes place also nearby spots. Weak flares with particle acceleration occur at the post-eruptive phase of the large flares and are often initiated by emergence of new magnetic fields inside active regions. When such an event is developed near the sector structure boundary and accompanied by the plasma ejection, this is a cause of subsequent powerful magnetic storm.