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arXiv · 1903.12279

Comparative analysis of solar radio bursts before and during CME propagation

G. Dididze·B. M. Shergelashvili·V. N. Melnik·V. V. Dorovskyy·A. I. Brazhenko·S. Poedts·T. V. Zaqarashvili·M. Khodachenko
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Abstract

As is well known, CME propagation often results in the fragmentation of the solar atmosphere on smaller regions of density (magnetic field) enhancement (depletion). It is expected that this type of fragmentation may have radio signatures. The general aim of the present paper is to perform a comparative analysis of type III solar and narrow-band type-III-like radio burst properties before and during CME events, respectively. The main goal is to analyze radio observational signatures of the dynamical processes in solar corona. In particular, we aim to perform a comparison of local plasma parameters without and with CME propagation, based on the analysis of decameter radio emission data. We performed a comparison of usual type III bursts before the CME with narrow-band type-III-like bursts, which are observationally detectable on top of the background type IV radio bursts associated with CME propagation. We focused on the analysis of in total 429 type III and 129 narrow-band type-III-like bursts. We studied their main characteristic parameters such as frequency drift rate, duration, and instantaneous frequency bandwidth using standard statistical methods. Furthermore, we inferred local plasma parameters using known definitions of frequency drift, duration, and instantaneous frequency bandwidth.The analysis reveals that the physical parameters of coronal plasma before CMEs considerably differ from those during the propagation of CMEs (the observational periods 2 and 4 with type IV radio bursts associated with CMEs). Local density radial profiles and the characteristic spatial scales of radio emission sources vary with radial distance more drastically during the CME propagation compared to the cases of quasistatic solar atmosphere without CME(s) (observational periods 1 and 3). The results of the work enable us to distinguish different regimes of plasma state in the solar corona.

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G. Dididze, B. M. Shergelashvili, V. N. Melnik, V. V. Dorovskyy, A. I. Brazhenko, S. Poedts, T. V. Zaqarashvili, M. Khodachenko. 2019-03-28. Comparative analysis of solar radio bursts before and during CME propagation. https://doi.org/10.1051/0004-6361%2F201629489

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