A Novel Fine Spectral Structure of Solar Radio Bursts with Periodic Beaded Stripes Observed by CBSm of CMP-II

TL;DR

This paper reports the discovery of a new fine spectral structure in solar radio bursts, characterized by periodic beaded stripes, observed with CBSm, and explains it through a double plasma resonance mechanism modulated by MHD waves.

Contribution

It introduces the first observation of beaded stripe structures in solar radio bursts and proposes a novel DPR-based generation mechanism for these features.

Findings

First detection of beaded stripe structures in solar radio bursts

Brightness temperature exceeds 10^9 K, indicating intense emission

Proposed DPR instability and MHD wave modulation as the origin

Abstract

A novel fine spectral structure in solar radio bursts has been discovered using the Chashan broadband solar radio spectrometer at meter wavelengths (CBSm), an instrument of the Chinese Meridian Project-Phase II (CMP-II). The structure features periodic narrow-band stripes with a typical recurrence time $< 1 $ s (occasionally reaches 8 s), often drifting from high to low frequencies and accompanied by absorptions, with trailing stripes appearing at the end of preceding ones. Some stripes exhibit periodic beaded enhancements with a periodicity of $\sim$0.1 s. The beaded stripes are reported for the first time ever. Data from the DAocheng Radio Telescope (DART) indicate a radio emission brightness temperature exceeding $10^{9}$ K, originating above brightening loops in active region AR 13664. We proposed a novel generation mechanism of the periodic stripes on the basis of the double plasma resonance (DPR) instability, and explained the beaded substructure in terms of modulation by low-frequency magnetohydrodynamic (MHD) waves. The study highlights the CBSm's capability to detect high-resolution fine spectral structures and offers novel insights into the emission mechanism and source characteristics of solar radio bursts.