射电天文研究组知识库

Two special fine structures observed with the 5.2-7.6 GHz high temporal and spectral resolution spectrometer of National Astronomical Observatories of China (NAOC) are described and analyzed in this paper. Because they appear as the letters N and M on dynamic spectra, we call them centimetric type N and type M bursts, respectively. They have very short durations (about 500 ins and 300 ms), small flux densities (tens of SFU), narrow bandwidth (relative bandwidth about 10\%), and very small polarization degree (close to the accuracy limit of observation instruments), but each branch has considerable high frequency drift rates (several GHz/s). We think that they are an extension of metric or decimetric type U(N) bursts in centimetric wavelengths. Type N and type M bursts may be due to the mirroring effect near the foot point, as well as a scattering effect caused by whistler wave turbulence near the top of loop. They may also be interpreted by the quasi-periodic particle injection into coronal loops.