Microwave observations of quasi-periodic pulsations ( QPP ) in multi-timescales are confirmed to be associated with an X3.4 flare/CME event at Solar Broadband Radio Spectrometer in Huairou ( SBRS/Huairou ) on 13 December 2006 .
It is most remarkable that the timescales of QPPs are distributed in a broad range from hecto-second ( very long period pulsation , VLP , the period P > 100 s ) , deca-second ( long period pulsation , LPP , 10 < P < 100 s ) , few seconds ( short period pulsation , SPP , 1 < P < 10 s ) , deci-second ( slow-very short period pulsation , slow-VSP , 0.1 < P < 1.0 s ) , to centi-second ( fast-very short period pulsation , fast-VSP , P < 0.1 s ) , and forms a broad hierarchy of timescales .
The statistical distribution in logarithmic period-duration space indicates that QPPs can be classified into two groups : group I includes VLP , LPP , SPP and part of slow-VSPs distributed around a line approximately ; group II includes fast-VSP and most of slow-VSP dispersively distributed away from the above line .
This feature implies that the generation mechanism of group I is different from group II .
Group I is possibly related with some MHD oscillations in magnetized plasma loops in the active region , e.g. , VLP may be generated by standing slow sausage mode coupling and resonating with the underlying photospheric 5-min oscillation , the modulation is amplified and forms the main framework of the whole flare/CME process ; LPP , SPP , and part of slow-VSPs are most likely to be caused by standing fast modes or LRC-circuit resonance in current-carrying plasma loops .
Group II is possibly generated by modulations of resistive tearing-mode oscillations in electric current-carrying flaring loops .