The Flare Emission of the May 4, 2022 Event and Its Millimeter Component

Based on observations at the RT-7.5 radio telescope of the Bauman Moscow State Technical University at a wavelength of 3.2 mm (93 GHz), along with other ground-based and space instruments (Siberian Radioheliograph, Solar Dynamics Observatory (SDO), Metsähovi Radio Observatory), the origin of millimeter radiation from X-ray class M 5.7 SOL2022-05-04T08:45 solar flare was investigated. An analysis of the time profiles of radiation in the X-ray and radio ranges showed that the millimeter emission source is not associated with hot (5 × 10 5 –10 7 K) coronal plasma. This is also evidenced by the estimate of the sub-THz flux from radiating hot plasma according to the AIA/SDO data, which turned out to be much less than the observed values. Indications of the development of thermal instability in flare ultraviolet loops were obtained. The relationship between the millimeter emission of the flare and the heat source in the solar chromosphere has been substantiated.