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Researchers analyzed an unusual multi-lane Type II solar radio burst observed on May 29, 2024, which revealed complex shock wave dynamics in the Sun's corona. By combining spectral and imaging data, they found that radio waves escaped through multiple distinct shock regions at the leading edge of a coronal mass ejection, creating additional splitting patterns beyond the traditional fundamental-harmonic and band-splitting structures. The study demonstrates that shock geometry and plasma inhomogeneity in the corona are critical factors in generating these radio bursts, with higher-frequency emissions occurring at higher altitudes than lower-frequency ones.
Why it matters
Understanding how shock waves propagate through the Sun's corona improves our ability to predict space weather events that can affect satellite communications, power grids, and GPS systems on Earth. This research provides new insights into the physical processes occurring during coronal mass ejections, which are major drivers of potentially harmful solar storms.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Type II solar radio bursts are considered as the signatures of the coronal shocks. These bursts are generated from plasma waves excited by magnetohydrodynamic (MHD) shocks, and then converted into radio waves at the local plasma frequency and/or its harmonics. Hence, these bursts often have fundamental-harmonic (FH) and band-splitting (SB) structures, which provide insights into shock generation and propagation in the corona, hence, in turn, the corresponding coronal conditions. In the present study, we analysed an unusual multi-lane type II burst observed with ground-based solar radio spectrographs on May 29, 2024, between 14:24 and 14:43 UT. The start and end frequencies of the type II burst were 450 MHz and 25 MHz, respectively. By combining spectral information with radio imaging data, we found that radio waves were escaping from the corona via emissions from distinct shock regions. In addition, along with the traditional FH and SB, there were multi-lane structures in the type II bursts. Our analysis suggests complex, inhomogeneous shock dynamics near the leading edge (LE) of the coronal mass ejection (CME). This indicates that the plasma material compresses more strongly in these forefront regions. This was confirmed by radio imaging observations, which showed that the higher-frequency emission occurred at a higher altitude than the lower-frequency emission. Our results suggest that the shock geometry and plasma inhomogeneity play an important role in the generation of type II bursts, leading to traditional fundamental-harmonic split-band (FH-SB) pairs with additional splitting in the type II bands.
Source: Multi-lane type II radio bursts: Insights into shock propagation in the corona