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Comparison of the properties of long‐lasting and impulsive type IV solar radio bursts with fine structures
Author(s) -
Chernov G. P.,
Poquerusse M.,
Bougeret J.L.,
Zlobec P.
Publication year - 2001
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2000rs002451
Subject(s) - physics , astrophysics , flare , solar flare , magnetic reconnection , current sheet , coronal mass ejection , polarization (electrochemistry) , astronomy , magnetic field , magnetohydrodynamics , solar wind , chemistry , quantum mechanics
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 Hα 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.