Rate of Solar Nanoflares in Different Spectral Ranges

The frequency and rate of solar nanoflares (NF) were measured in 6 coronal spectral ranges (094, 131, 171, 193, 211, 335 Å) and one, related to the transition layer (304 Å). We used SDO/AIA data obtained at solar minimum in May 2019. We analyzed the same region of the Sun, covering 360”× 720” field-of-view, in all channels over the same time interval of 1 hour. In all the spectral bands, to search for NF we applied the same algorithm based on the amplitude analysis of fast brightenings in AIA images. The frequency and rate of NF, as can be expected, vary significantly in different wavelengths. For threshold 5σ , the highest NF frequency, 207 s –1 , was measured in 171 Å. The next spectral ranges are 193 Å (85