000005333 001__ 5333
000005333 005__ 20210502163618.0
000005333 0247_ $$2DOI$$a10.1051/0004-6361/202140380
000005333 037__ $$aSCART-2021-0080
000005333 100__ $$aBerghmans, D.
000005333 245__ $$aExtreme-UV quiet Sun brightenings observed by the Solar Orbiter/EUI
000005333 260__ $$c2021
000005333 520__ $$aContext. 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 0.556AU from the Sun. Its High Resolution EUV telescope (HRIEUV, 17.4nm 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 (SDO) 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 sec and 200 sec. 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 (DEM) 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 chromo- spheric 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.
000005333 536__ $$a PRODEX contract number 4000112292/$$c PRODEX contract number 4000112292/$$f PRODEX contract number 4000112292
000005333 594__ $$aSTCE
000005333 6531_ $$aSun: UV radiation
000005333 6531_ $$aSun: transition region
000005333 6531_ $$aSun: corona
000005333 6531_ $$aInstrumentation: high angular resolution
000005333 700__ $$aAuchère, F.
000005333 700__ $$aLong, D. M.
000005333 700__ $$aSoubrié, E.
000005333 700__ $$aMierla, M.
000005333 700__ $$aZhukov, A.N.
000005333 700__ $$aSchühle, U.
000005333 700__ $$aAntolin, P.
000005333 700__ $$aHarra, L.
000005333 700__ $$aParenti, S.
000005333 700__ $$aPodladchikova, O.
000005333 700__ $$aAznar Cuadrado, R.
000005333 700__ $$aBuchlin, E.
000005333 700__ $$aDolla, L.
000005333 700__ $$aVerbeeck, C.
000005333 700__ $$aGissot, S.
000005333 700__ $$aTeriaca, L.
000005333 700__ $$aHaberreiter, M.
000005333 700__ $$aKatsiyannis, A. C.
000005333 700__ $$aRodriguez, L.
000005333 700__ $$aKraaikamp, E.
000005333 700__ $$aSmith, P.J.
000005333 700__ $$aStegen, K.
000005333 700__ $$aRochus, P.
000005333 700__ $$aHalain, J. P.
000005333 700__ $$aJacques, L.
000005333 700__ $$aThompson, W.T.
000005333 700__ $$aInhester, B
000005333 773__ $$nSpecial Issue "Solar Orbiter First Results"$$pAstronomy and Astrophysics$$y2021
000005333 8560_ $$fdavid.berghmans@observatoire.be
000005333 85642 $$ahttps://www.aanda.org/articles/aa/pdf/forth/aa40380-21.pdf
000005333 85642 $$ahttps://doi.org/10.1051/0004-6361/202140380
000005333 905__ $$aaccepted to be published in
000005333 980__ $$aREFERD