Abstract
We study an M2.6 flare observed with RHESSI on 22 August 2005. The light curves of the hard X-rays (counts and photon fluxes), the derived number fluxes, as well as the energy fluxes of energetic electrons all presented a damped quasi-periodic oscillation. The modulation depth of the hard X-rays increased with the energies. For the energy fluxes of energetic electrons, the modulation depth can be as high as 90%. During the oscillations, however, the plasma temperature had no apparent change. No correspondence was found between the motions of the flare loops and the quasi-periodic oscillations. We conclude that an oscillation with a high modulation depth for a period of about four minutes cannot be easily explained with the existing mechanisms.
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Li, Y.P., Gan, W.Q. Observational Studies of the X-Ray Quasi-Periodic Oscillations of a Solar Flare. Sol Phys 247, 77–85 (2008). https://doi.org/10.1007/s11207-007-9092-5
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DOI: https://doi.org/10.1007/s11207-007-9092-5