Article (Scientific journals)
Extreme-UV quiet Sun brightenings observed by the Solar Orbiter/EUI
Berghmans, D.; Auchère, F.; Long, D.M. et al.
2021In Astronomy and Astrophysics, 656, p. 4
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Keywords :
Instrumentation: high angular resolution; Sun: corona; Sun: transition region; Sun: UV radiation; Extreme ultraviolet imager; High resolution; Instrumentation:high angular resolution; Pass bands; Quiet Sun; Small scale; Solar Orbiters; Sun : corona; Sun:transition region; Sun:UV radiation; Astronomy and Astrophysics; Space and Planetary Science; astro-ph.SR
Abstract :
[en] Context. The heating of the solar corona by small heating events requires an increasing number of such events at progressively smaller scales, with the bulk of the heating occurring at scales that are currently unresolved. Aims. The goal of this work is to study the smallest brightening events observed in the extreme-UV quiet Sun. Methods. We used commissioning data taken by the Extreme Ultraviolet Imager (EUI) on board the recently launched Solar Orbiter mission. On 30 May 2020, the EUI was situated at 0.556 AU from the Sun. Its High Resolution EUV telescope (HRIEUV, 17.4 nm passband) reached an exceptionally high two-pixel spatial resolution of 400 km. The size and duration of small-scale structures was determined by the HRIEUV data, while their height was estimated from triangulation with simultaneous images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory mission. This is the first stereoscopy of small-scale brightenings at high resolution. Results. We observed small localised brightenings, also known as 'campfires', in a quiet Sun region with length scales between 400 km and 4000 km and durations between 10 s and 200 s. The smallest and weakest of these HRIEUV brightenings have not been previously observed. Simultaneous observations from the EUI High-resolution Lyman-α telescope (HRILya) do not show localised brightening events, but the locations of the HRIEUV events clearly correspond to the chromospheric network. Comparisons with simultaneous AIA images shows that most events can also be identified in the 17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA, although they appear weaker and blurred. Our differential emission measure analysis indicated coronal temperatures peaking at log T ≈ 6.1 - 6.15. We determined the height for a few of these campfires to be between 1000 and 5000 km above the photosphere. Conclusions. We find that 'campfires' are mostly coronal in nature and rooted in the magnetic flux concentrations of the chromospheric network. We interpret these events as a new extension to the flare-microflare-nanoflare family. Given their low height, the EUI 'campfires' could stand as a new element of the fine structure of the transition region-low corona, that is, as apexes of small-scale loops that undergo internal heating all the way up to coronal temperatures.
Disciplines :
Aerospace & aeronautics engineering
Author, co-author :
Berghmans, D.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Auchère, F.;  Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, Orsay, France
Long, D.M.;  UCL-Mullard Space Science Laboratory, Surrey, United Kingdom
Soubrié, E.;  Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, Orsay, France ; Institute of Applied Computing and Community Code, Universitat de les Illes Balears, Palma de Mallorca, Spain
Mierla, M.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium ; Institute of Geodynamics, Romanian Academy, Bucharest, Romania
Zhukov, A.N.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium ; Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russian Federation
Schühle, U.;  Max Planck Institute for Solar System Research, Göttingen, Germany
Antolin, P.;  Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne, United Kingdom
Harra, L.;  Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Switzerland ; ETH-Zürich, Zürich, Switzerland
Parenti, S.;  Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, Orsay, France
Podladchikova, O.;  Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Switzerland
Aznar Cuadrado, R.;  Max Planck Institute for Solar System Research, Göttingen, Germany
Buchlin, E.;  Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, Orsay, France
Dolla, L.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Verbeeck, C.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Gissot, S.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Teriaca, L.;  Max Planck Institute for Solar System Research, Göttingen, Germany
Haberreiter, M.;  Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Switzerland
Katsiyannis, A.C.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Rodriguez, L.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Kraaikamp, E.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Smith, P.J.;  UCL-Mullard Space Science Laboratory, Surrey, United Kingdom
Stegen, K.;  Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
Rochus, Pierre  ;  Université de Liège - ULiège > Département d'aérospatiale et mécanique
Halain, J.P.;  Centre Spatial de Liège, Université de Liège, Angleur, Belgium ; European Space Agency (ESA/ESTEC), Noordwijk, Netherlands
Jacques, Lionel  ;  Université de Liège - ULiège > Centres généraux > CSL (Centre Spatial de Liège)
Thompson, W.T.;  Adnet Systems Inc., NASA Goddard Space Flight Center, Greenbelt, United States
Inhester, B.;  Max Planck Institute for Solar System Research, Göttingen, Germany
More authors (18 more) Less
Language :
English
Title :
Extreme-UV quiet Sun brightenings observed by the Solar Orbiter/EUI
Publication date :
December 2021
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences
Volume :
656
Pages :
L4
Peer reviewed :
Peer Reviewed verified by ORBi
Funding text :
Acknowledgements. The building of EUI was the work of more than 150 people during more than 10 years, we gratefully acknowledge all the efforts that have led to a successfully operating instrument. The authors thank the Belgian Federal Science Policy Office (BELSPO) for the provision of financial support in the framework of the PRODEX Programme of the European Space Agency (ESA) under contract number 4000112292. The French contribution to the EUI instrument was funded by the French Centre National d’Etudes Spatiales (CNES); the UK Space Agency (UKSA); the Deutsche Zentrum für Luft-und Raum-fahrt e.V. (DLR); and the Swiss Space Office (SSO). PA and DML acknowledge funding from STFC Ernest Rutherford Fellowships No. ST/R004285/2 and ST/R003246/1, respectively. SP acknowledges the funding by CNES through the MEDOC data and operations center.
Commentary :
12 pages, 14 figures
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since 25 November 2022

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