A rare large Type Ⅳμ burst, appeared above active region NOAA/USAF 5278 was observed at Yunnan Observatory with Phoenix Ⅱ Microwave Spectrometer at three frequencies (4 00, 2 84 and 1 42 GHz) on December 16, 1988. ...A rare large Type Ⅳμ burst, appeared above active region NOAA/USAF 5278 was observed at Yunnan Observatory with Phoenix Ⅱ Microwave Spectrometer at three frequencies (4 00, 2 84 and 1 42 GHz) on December 16, 1988. The burst consisted of 5 main peaks with a quasiperiod of 12 5 min, on which many complex millisecond spike emissions were superimposed. Within the first main peak there were 8 secondary peaks with a quasi period of 98s (at 4 00 GHz), 72s (2 84 GHz) and 60s (1 42 GHz). A semi quantitative explanation is given for the variation of the quasi period with frequency in terms of MHD modulated oscillations in the magnetic flux tube.展开更多
文摘A rare large Type Ⅳμ burst, appeared above active region NOAA/USAF 5278 was observed at Yunnan Observatory with Phoenix Ⅱ Microwave Spectrometer at three frequencies (4 00, 2 84 and 1 42 GHz) on December 16, 1988. The burst consisted of 5 main peaks with a quasiperiod of 12 5 min, on which many complex millisecond spike emissions were superimposed. Within the first main peak there were 8 secondary peaks with a quasi period of 98s (at 4 00 GHz), 72s (2 84 GHz) and 60s (1 42 GHz). A semi quantitative explanation is given for the variation of the quasi period with frequency in terms of MHD modulated oscillations in the magnetic flux tube.
