Issue |
A&A
Volume 663, July 2022
|
|
---|---|---|
Article Number | A128 | |
Number of page(s) | 12 | |
Section | The Sun and the Heliosphere | |
DOI | https://doi.org/10.1051/0004-6361/202243257 | |
Published online | 21 July 2022 |
Automatic detection of small-scale EUV brightenings observed by the Solar Orbiter/EUI⋆
1
Department of Physics, Faculty of Science, University of Zanjan, University Blvd., Zanjan, 45371-38791 Zanjan, Iran
e-mail: safari@znu.ac.ir
2
Observatory, Faculty of Science, University of Zanjan, University Blvd., Zanjan, 45371-38791 Zanjan, Iran
3
Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, Ringlaan -3- Av. Circulaire, 1180 Brussels, Belgium
4
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
5
Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
6
Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK
7
ETH-Zürich, Hönggerberg campus, HIT Building, Zürich, Switzerland
8
Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, 7260 Davos Dorf, Switzerland
9
RCAAM of the Academy of Athens, 4 Soranou Efesiou Street, 11527 Athens, Greece
10
UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
11
Leibniz Institute for Astrophysics in Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
12
Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, 3001 Leuven, Belgium
13
Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA
14
Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119992, Moscow, Russia
Received:
3
February
2022
Accepted:
1
April
2022
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 Å 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 × 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-α 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.
Key words: Sun: corona / Sun: UV radiation / techniques: high angular resolution
Supplementary material (S1–S3) is available at https://www.aanda.org
© ESO 2022
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