Morphology of Solar Type II Bursts Caused by Shock Propagation through Turbulent and Inhomogeneous Coronal Plasma

0574430 - ASÚ 2024 RIV GB eng J - Journal Article
Koval, Artem - Stanislavsky, A. - Karlický, Marian - Wang, B. - Yerin, S. N. - Konovalenko, A. - Bárta, Miroslav
Morphology of Solar Type II Bursts Caused by Shock Propagation through Turbulent and Inhomogeneous Coronal Plasma.
Astrophysical Journal. Roč. 952, č. 1 (2023), č. článku 51. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GC21-16508J; GA ČR(CZ) GA22-34841S
Institutional support: RVO:67985815
Keywords : solar coronal mass ejections * solar activity * solar telescopes
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 4.9, year: 2022
Method of publishing: Open access

Type II solar bursts are radio signatures of shock waves in the solar corona driven by solar flares or coronal mass ejections (CMEs). Therefore, these bursts present complex spectral morphologies in solar dynamic spectra. Here, we report meter-decameter radio observations of a type II burst on 2014 July 25 made with the Ukrainian radio telescopes UTR-2 (8.25-33 MHz) and GURT (8.25-78 MHz). The burst demonstrates fundamental and harmonic components, band splitting, a herringbone structure, and a spectral break. These specific spectral features, observed jointly in a single type II burst, are rarely detected. To contribute to our understanding of such puzzling type II events, we carried out a detailed analysis of the recorded type II dynamic spectrum. In particular, the herringbone pattern has been exploited to study electron density turbulence in the solar corona. We calculated the power spectral densities of the flux variations in selected herringbones. The spectral index is in the range of & alpha, =1.69 to2.00 with an average value of1.897, which is slightly higher than the Kolmogorov spectral index of5/3 for fully developed turbulence. We also recognized that the second type II burst consists of three drifting lanes. The lane onset times coincide with the spectral break in the first type II burst. We regard that the CME/shock passage through a streamer caused the spectral break and triggered the multilane type II radio emission. Thus, we support one of the proposed scenarios for type II burst occurrence as being the result of CME/shock-streamer interaction.
Permanent Link: https://hdl.handle.net/11104/0345191