Gennady Chernov

Type II solar radio bursts are among the most powerful events in the solar radio emission in the meter wavelength range. It is generally accepted that the agents generating type II radio bursts are magnetohydrodynamic shock waves. But the relationship between the shock waves and the other manifestations of the large-scale disturbances in the solar atmosphere (coronal mass ejections, Morton waves, EUW waves) remains unclear. To clarify a problem, it is important to determine the conditions of generation of type II radio bursts. Here, the model of the radio source is based on the generation of radio emission within the front of the collisionless shock wave where the Buneman instability of plasma waves is developed. In the frame of this model, the Alfvén magnetic Mach number must exceed the critical value, and there is a strict restriction on the perpendicularity of the front. The model allows us to obtain the information about the parameters of the shock waves and the parameters of th...

This review covers the most recent experimental results and theoretical re-search on zebra patterns (ZPs) in solar radio bursts. The basic attention is given to events with new peculiar elements of zebra patterns received over the last few years. All new properties are considered in light of both what was known earlier and new theoretical models. Large-scale ZPs consisting of small-scale fiber bursts could be explained by simultaneous inclusion of two mechanisms when whistler waves “high-light ” the levels of double plasma resonance (DPR). A unique fine structure was ob-served in the event on 2006 December 13: spikes in absorption formed dark ZP stripes against the absorptive type III-like bursts. The spikes in absorption can appear in ac-cordance with well known mechanisms of absorptive bursts. The additional injection of fast particles filled the loss-cone (breaking the loss-cone distribution), and the gen-eration of the continuum was quenched at these moments. The maximum absorpt...

The publications of the last three years concerning the study of the most intriguing fine structure in type IV solar radio bursts, zebra pattern (ZP), are surveyed. The main attention is paid to new observations, irrespective of whether a paper includes detailed interpretation of an event or simply reports the beginning of operation of a new tool. The radiation mechanism of a ZP on a double plasma resonance (DPR) remains the most widespread and standard, though ten alternative mechanisms have been offered. However, in a number of works difficulties with the explanation of a complex zebra are noted, especially in combination with fiber bursts and spikes. Therefore, several papers in which description of the radiation mechanism of a ZP on the DPR is improved are considered in more detail. Without positional observations we have a great opportunity to follow the dynamics of flare processes using SDO / AIA images in several EUV lines. In the discussion, the debatable questions regarding...

ABSTRACT We consider source positions of fine structures (mainly of zebra pattern) and of continuum emission in some type IV radio bursts with respect to optical and X-ray features. For completeness, dynamic spectra of fine structures recorded in different observatories were compared with each other and with records of circular left and right polarization at single frequencies. We analyzed three long-lasting type IV events (events 1989 03 12, 1990 06 05, and 1992 02 17) that were characterized by the absence of microwave bursts and big flares and two impulsive events (events 1990 06 11 and 1994 10 25) formed by type II bursts and by rather short living type IV continuum in close relation to Halpha flares and microwave bursts. All those events were connected with active filaments. As an example of more complex events, including both impulsive and long-lasting type IV bursts, event 1997 11 04 is considered. A general peculiarity of fine structures in the three long-lasting events is the long-term evolution of zebra patterns and pulsations (2-3 hours), which testifies to the presence of repeated acceleration of fast particles in vertical current sheets during the restoration of magnetic arches after the escape of coronal mass ejections. The magnetic configurations in the source of the impulsive events must be rather close to oblique flare current sheets. Complex events can have a two-step evolution: The former regards the reconnection in low flaring loops, while the latter is related to the reconnection in the higher corona.