Journal ArticleEnigmatic Centi-SFU and mSFU Nonthermal Radio Transients Detected in the Middle CoronaMondal, Surajit (ORCID:0000000223255298); Chen, Bin (ORCID:0000000206603350); Yu, Sijie (ORCID:0000000328722614); Chen, Xingyao (ORCID:0000000218106706); Zhang, Peijin (ORCID:0000000168555799); Gary, Dale (ORCID:0000000325208396); Anderson, Marin M (ORCID:0000000322382698); Bowman, Judd D (ORCID:0000000284752036); Byrne, Ruby (ORCID:0000000349802736); Catha, Morgan; Chhabra, Sherry (ORCID:0000000177540804); D’Addario, Larry; Davis, Ivey (ORCID:0000000153975969); Dowell, Jayce (ORCID:0000000314070141); Hallinan, Gregg (ORCID:0000000270834049); Harnach, Charlie; Hellbourg, Greg (ORCID:0000000281913885); Hickish, Jack (ORCID:0000000302161417); Hobbs, Rick; Hodge, David; Hodges, Mark; Huang, Yuping (ORCID:0000000342676108); Isella, Andrea (ORCID:0000000180612207); Jacobs, Daniel C (ORCID:0000000209172269); Kemby, Ghislain; Klinefelter, John T; Kolopanis, Matthew (ORCID:0000000229502974); Kosogorov, Nikita (ORCID:000000031226118X); Lamb, James (ORCID:0000000259591285); Law, Casey (ORCID:0000000241199963); Mahesh, Nivedita; O’Donnell, Brian (ORCID:000000032802850X); Plant, Kathryn (ORCID:0000000163606972); Posner, Corey; Powell, Travis; Prayag, Vinand; Rizo, Andres; Romero-Wolf, Andrew (ORCID:0000000249924162); Shi, Jun (ORCID:0000000316477762); Taylor, Greg (ORCID:0000000164957731); Trim, Jordan; Virgin, Mike; Vydula, Akshatha (ORCID:0000000266112668); Weinreb, Sandy; White, Scott; Woody, David (ORCID:0000000317342472); Zentmeyer, Thomas<title>Abstract</title> <p>Decades of solar coronal observations have provided substantial evidence for accelerated particles in the corona. In most cases, the location of particle acceleration can be roughly identified by combining high spatial and temporal resolution data from multiple instruments across a broad frequency range. In almost all cases, these nonthermal particles are associated with quiescent active regions, flares, and coronal mass ejections (CMEs). Only recently, some evidence of the existence of nonthermal electrons at locations outside these well-accepted regions has been found. Here, we report for the first time multiple cases of transient nonthermal emissions, in the heliocentric range of ∼3–7<italic>R</italic>_⊙, which do not have any obvious counterparts in other wave bands, like white-light and extreme ultraviolet. These detections were made possible by the regular availability of high dynamic-range low-frequency radio images from the Owens Valley Radio Observatory’s Long Wavelength Array. While earlier detections of nonthermal emissions at these high heliocentric distances often had comparable extensions in the plane of sky, they were primarily associated with radio CMEs, unlike the cases reported here. Thus, these results add on to the evidence that the middle corona is extremely dynamic and contains a population of nonthermal electrons, which is only becoming visible with high dynamic-range low-frequency radio images.</p>IOP Publishing2025-12-0110665232The Astrophysical Journal99422540004-637Xhttps://doi.org/10.3847/1538-4357/ae113b2436999National Science Foundation