Newly detected rhythmic radio signals shed light on solar atmospheric structures
by Riko Seibo
Tokyo, Japan (SPX) Oct 23, 2025

Researchers in China have unveiled a previously unknown pattern in solar radio emissions, observed during a major flare on May 8, 2024. The discovery comes from observations made using the Chashan Broadband Solar Radio Spectrometer (CBSm), which records solar signals between 90 and 600 MHz. Scientists identified a series of bright, narrow bands drifting slowly down in frequency, each less than 1 MHz wide and followed by brief, faint absorption regions. The entire chain occupied less than 10 MHz, and remarkably, the bands contained repeating "beads" - tiny rhythmic dots spaced about every tenth of a second.

This observation was only possible due to the high time and frequency resolution of CBSm. Additional imaging by the Daocheng Radio Telescope confirmed the emissions originated above flare loops in an active region of the Sun.

The research team proposes that double plasma resonance is responsible for the primary stripes - where electrons trapped in specific magnetic and plasma conditions emit radio waves at preferred frequencies. This process, already known for producing "zebra stripes," appears here within a limited range of solar atmospheric heights. The beads themselves are thought to result from magnetohydrodynamic waves oscillating through solar plasma, modulating the radio emissions. Measurements at the radio source indicate a weak magnetic field of approximately one gauss, suggesting the activity occurred high above the Sun's surface or at a junction of multiple loops.

This new discovery expands the catalogue of fine solar radio structures and demonstrates how modern instruments like CBSm are enabling fresh insights into the Sun's complexity.

Research Report:A novel fine spectral structure of solar radio bursts with periodic beaded stripes observed by CBSm of CMP-II

Related Links
Shandong University
Solar Science News at SpaceDaily