On the origin of microwave zebra pattern

¹ Institute of Solar-Terrestrial Physics, Siberian Branch of the Russian Academy of Sciences, PO Box 4026, Irkutsk 33, 664033, Russia e-mail: [altyntsev;a_kuzn]@iszf.irk.ru
² National Astronomical Observatories, Chinese Academy of Sciences, Datun Road A20, Chaoyang District, Beijing 100012, PR China e-mail: yyh@bao.ac.cn

Received: 24 May 2004
Accepted: 6 October 2004

Abstract

The results of the first observations of a zebra pattern at frequencies around 5.6 GHz are presented. The fine structures in the emission spectrum were recorded simultaneously by the Siberian Solar Radiotelescope and the spectropolarimeters of the National Astronomical Observatories, which allowed us to study the presented event with high spatial, temporal and spectral resolution. The apparent source size does not exceed 10 arcsec, and the sources of the different stripes of the zebra structure coincide spatially. The circular polarization degree reaches 100%, and the polarization sense corresponds to the extraordinary wave. We argue that the most probable generation mechanism of the zebra pattern is nonlinear coupling of Bernstein waves. In this case the value of the magnetic field in the burst source, determined by the frequency separation between the adjacent stripes, is 60–80 G.