A unified explanation of solar type IV dm continua and zebra patterns

Both type IV dm continuum radiation and zebra patterns can have their origin in plasma waves at the upper hybrid frequency, which are excited by a loss-cone distribution of fast electrons superposed on the thermal background. If the inverse fractional density of fast electrons surpasses the ratio of the electron plasma frequency to the electron cyclotron frequency, instability only exists at those places in the corona where this ratio is integer, thus giving rise to zebra patterns. Some observations in favour of the present explanation are discussed. Upper limits to the magnetic field strength and the fast particle density in the source are derived from the observations. (orig.)