A solar jet-induced perturbation propagating through coronal loops and in-loop electron beam transport as indicated by type II and type N radio bursts

¹ School of Space Science and Technology, Institute of Space Sciences, Shandong Key Laboratory of Space Environment and Exploration Technology, Shandong University Weihai Shandong 264209, PR China
² Institute of Frontier and Interdisciplinary Science, Shandong University Qingdao Shandong 266237, PR China
³ Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS Nanjing 210023, PR China
⁴ Yunnan Observatories, Chinese Academy of Sciences Kunming Yunnan 650216, PR China

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 21 April 2025
Accepted: 20 December 2025

Abstract

Aims. Solar type II radio bursts are commonly attributed to coronal shocks driven by coronal mass ejections (CMEs). However, some metric type II bursts have occasionally been reported to occur in the absence of a CME and to be associated with weak solar activity. The aim of this study is to identify the driver of the coronal shock in this kind of type II event.

Methods. We investigated a high-frequency metric type II burst with clear band splitting, observed simultaneously by the Chashan Broadband Solar radio spectrograph and the Nançay Radioheliograph. It is associated with a C3.1-class flare and a small-scale jet, but without a detectable CME in the coronagraphs.

Results. The type II burst is preceded by multiple type III bursts, one of which exhibits characteristics of a type N burst. The type II burst source is associated with the jet-induced perturbation front propagating through nearby closed loops at a speed of ∼880 km s⁻¹, rather than the much slower jet front. This suggests that the disturbance initiated by the jet can convert to a shock wave within low Alfvénic coronal loops, providing the necessary conditions for electron acceleration and subsequent radio emission. Our findings offer new insights into the formation mechanism of high-frequency type II bursts associated with weak flares and jets.