edu.ucar.opensky::articles:27278 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-24T18:50:50.712868 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7n01brd Imaging spectroscopy of a spectral bump in a type II radio burst 2024-04-24T00:00:00Z publication https://n2t.org/ark:/85065/d7n01brd https://doi.org/10.1051/0004-6361/202449365 Zhang 张, PeiJin 沛锦 author Morosan, D. E. author Zucca, P. author Normo, S. author Dabrowski, B. author Krankowski, A. author Vocks, C. author UCAR/NCAR - Library publisher Context. Observations of solar, type II radio bursts provide a unique opportunity to analyze the nonthermal electrons accelerated by coronal shocks and diagnose the plasma density distribution in the corona. However, there are very few high-frequency resolution interferometric observations of type II radio bursts that are capable of tracking these electrons. Aims. Recently, more spatially resolved high-resolution observations of type II radio bursts have been recorded with the Low-Frequency Array (LOFAR). Using these observations, we aim to track the location of a type II radio burst that experienced a sudden spectral bump. Methods. We present the first radio imaging observations of a type II burst with a spectral bump. We measured the variation in source location and frequency drift of the burst and deducted the density distribution along its propagation direction. Results. We have identified a type II burst that experiences a sudden spectral bump in its frequency-time profile. The overall frequency drift rate is 0.06 MHz s(-1), and this corresponds to an estimated speed of 295 km s(-1). The projected velocity of the radio source obtained from imaging is 380 km s(-1) toward the east. At the spectral bump, a deviation in the source locations of the type II split bands is observed. The band separation increases significantly in the north-south direction. Conclusions. The spectral bump shows an 8 MHz deviation at 60 MHz, which corresponds to a 25% decrease in the plasma density. The estimated crossing distance during the spectrum bump was 29 mm, suggesting that this density variation occurs in a confined area. This indicates that the shock most likely encountered the upper extent of a coronal hole. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation