Journal
ASTRONOMY & ASTROPHYSICS
Volume 663, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202243257
Keywords
Sun: corona; Sun: UV radiation; techniques: high angular resolution
Categories
Funding
- Belgian Federal Science Policy Office [BELSPO/PRODEX PEA 4000112292]
- Centre National d'Etudes Spatiales (CNES)
- UK Space Agency (UKSA)
- Bundesministerium fur Wirtschaft und Energie (BMWi) through the Deutsches Zentrum fur Luft-und Raumfahrt (DLR)
- Swiss Space O ffice (SSO)
- Belgian Federal Science Policy Office (BELSPO) [4000134474, 4000134088, 4000136424]
- Swiss National Science Foundation -SNF
- STFC [ST/R004285/2, ST/R003246/1]
- CNES through the MEDOC data and operation center
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This study detects small-scale brightenings, referred to as campfires, using their morphological and intensity structures observed in coronal EUV imaging observations. By applying a method based on Zernike moments and a support vector machine classifier, the researchers are able to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA). The results show that campfires are often formed at supergranular boundaries and that features with the highest total intensities are generated at network junctions and intense H I Lyman-alpha emission regions observed by EUI /HRILya.
Context. Accurate detections of frequent small-scale extreme ultraviolet (EUV) brightenings are essential to the investigation of the physical processes heating the corona. Aims. We detected small-scale brightenings, termed campfires, using their morphological and intensity structures as observed in coronal EUV imaging observations for statistical analysis. Methods. We applied a method based on Zernike moments and a support vector machine (SVM) classifier to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA). Results. This method detected 8678 campfires (with length scales between 400 km and 4000 km) from a sequence of 50 High Resolution EUV telescope (HRIEUV) 174 angstrom images. From 21 near co-temporal AIA images covering the same field of view as EUI, we found 1131 campfires, 58% of which were also detected in HRIEUV images. In contrast, about 16% of campfires recognized in HRIEUV were detected by AIA. We obtain a campfire birthrate of 2 x 10(-16) m(-2) s(-1). About 40% of campfires show a duration longer than 5 s, having been observed in at least two HRIEUV images. We find that 27% of campfires were found in coronal bright points and the remaining 73% have occurred out of coronal bright points. We detected 23 EUI campfires with a duration greater than 245 s. We found that about 80% of campfires are formed at supergranular boundaries, and the features with the highest total intensities are generated at network junctions and intense H I Lyman-alpha emission regions observed by EUI /HRILya. The probability distribution functions for the total intensity, peak intensity, and projected area of campfires follow a power law behavior with absolute indices between 2 and 3. This self-similar behavior is a possible signature of self-organization, or even self-organized criticality, in the campfire formation process.
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