Centimetric type N and type M bursts

¹ Yunnan Observatory, National Astronomical Observatories, Chinese Academy of Science, Kunming 650011, PR China
² National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, PR China e-mail: wmynao@163.net

Corresponding author: M. Wang, wmynao@163.net

Received: 26 September 2000
Accepted: 27 June 2001

Abstract

Two special fine structures observed with the 5.2-7.6 GHz high temporal and spectral resolution spectrometer of Beijing Astronomical Observatory (BAO) 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 ms 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.