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The \textit{Sun Watcher using Active Pixel system detector and Image Processing}(SWAP) on board the \textit{PRoject for OnBoard Autonomy\todash 2} (PROBA\todash 2) spacecraft provides images of the solar corona in EUV channel centered at…

Solar and Stellar Astrophysics · Physics 2012-06-11 K. Chandrashekhar , S. Krishna Prasad , D. Banerjee , B. Ravindra , Daniel B. Seaton

Coronal active regions are observed to get fuzzier and fuzzier (i.e. more and more confused and uniform) in harder and harder energy bands or lines. We explain this evidence as due to the fine multi-temperature structure of coronal loops.…

Solar and Stellar Astrophysics · Physics 2015-05-19 Massimiliano Guarrasi , Fabio Reale , Giovanni Peres

We model a coronal loop as a bundle of seven separate strands or filaments. Each of the loop strands used in this model can independently be heated (near their left footpoints) by Alfv\'en/ion-cyclotron waves via wave-particle interactions.…

Solar and Stellar Astrophysics · Physics 2014-11-20 S. Bourouaine , E. Marsch

We report on the detection (10 \sigma) of 917 events of long-period (3 to 16 hours) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e the…

Solar and Stellar Astrophysics · Physics 2014-03-05 F. Auchère , K. Bocchialini , J. Solomon , E. Tison

Without any doubt solar flaring loops possess a multi-thread internal structure that is poorly resolved and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause…

Solar and Stellar Astrophysics · Physics 2015-11-04 R. Falewicz , P. Rudawy , K. Murawski , A. K. Srivastava

We perform multiwavelength time-distance analysis of a fan loop system anchored in an isolated sunspot region AR 12553. The active region was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We measure…

Solar and Stellar Astrophysics · Physics 2020-07-01 Aishawnnya Sharma , Durgesh Tripathi , Robertus Erdelyi , G. R. Gupta , G. A. Ahmed

Coronal rain is the most dramatic cooling phenomenon of the solar corona and an essential diagnostic tool for the coronal heating properties. A puzzling feature of the solar corona, besides the heating, is its EUV filamentary structure and…

We investigate intensity variations and energy deposition in five coronal loops in active region cores. These were selected for their strong variability in the AIA/SDO 94 {\AA} intensity channel. We isolate the hot Fe XVIII and Fe XXI…

Solar and Stellar Astrophysics · Physics 2015-06-19 A. C. Cadavid , J. K. Lawrence , D. J. Christian , D. B. Jess , G. Nigro

Context: The common flare scenario comprises an acceleration site in the corona and particle transport to the chromosphere. Using satellites available to date it has become possible to distinguish between the two processes of acceleration…

Astrophysics · Physics 2011-02-19 Marina Battaglia , Arnold O. Benz

The large-amplitude longitudinal oscillations of solar filaments have been observed and explored for more than ten years. Previous studies are mainly based on the one-dimensional rigid flux tube model with a single magnetic dip. However, it…

Solar and Stellar Astrophysics · Physics 2017-04-19 Yu-Hao Zhou , Li-Yue Zhang , Y. Ouyang , P. F. Chen , C. Fang

Decayless kink oscillations are omnipresent in the solar atmosphere and a viable candidate for coronal heating. Though there have been extensive studies of decayless oscillations in coronal loops with a few hundred Mm lengths, the…

We present the first Hinode/EIS observations of 5 min quasi-periodic oscillations detected in a transition-region line (He II) and five coronal lines (Fe X, Fe XII, Fe XIII, Fe XIV, and Fe XV) at the footpoint of a coronal loop. The…

Solar and Stellar Astrophysics · Physics 2010-11-11 T. J. Wang , L. Ofman , J. M. Davila

We performed for the first time stereoscopic triangulation of coronal loops in active regions over the entire range of spacecraft separation angles ($\alpha_{sep}\approx 6^\circ, 43^\circ, 89^\circ, 127^\circ$, and $170^\circ$). The…

Solar and Stellar Astrophysics · Physics 2015-06-05 Markus J. Aschwanden , Jean-Pierre Wülser , Nariaki Nitta , James Lemen

The high-cadence, comprehensive view of the solar corona by SDO/AIA shows many events that are widely separated in space while occurring close together in time. In some cases, sets of coronal events are evidently causally related, while in…

Solar and Stellar Astrophysics · Physics 2015-06-15 C. J. Schrijver , A. M. Title , A. R. Yeates , M. L. DeRosa

Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a…

Solar and Stellar Astrophysics · Physics 2015-09-23 Tongjiang Wang , Leon Ofman , Xudong Sun , Elena Provornikova , Joseph M. Davila

The heating of solar coronal loops is at the center of the problem of coronal heating. Given that the origin of the fast solar wind has been tracked down to atmospheric layers with transition region or even chromospheric temperatures, it is…

Solar and Stellar Astrophysics · Physics 2014-06-05 Bo Li , Haixia Xie , Xing Li , Li-Dong Xia

Any successful model of coronal loops must explain a number of observed properties. For warm (~ 1 MK) loops, these include: 1. excess density, 2. flat temperature profile, 3. super-hydrostatic scale height, 4. unstructured intensity…

Solar and Stellar Astrophysics · Physics 2014-11-20 J. A. Klimchuk , J. T. Karpen , S. K. Antiochos

Solar flares form and release energy across a large number of magnetic loops. The global parameters of flares, such as the total energy released, duration, physical size, etc., are routinely measured, and the hydrodynamics of a coronal loop…

Solar and Stellar Astrophysics · Physics 2018-04-18 Jeffrey W. Reep , Vanessa Polito , Harry P. Warren , Nicholas A. Crump

Spatially unresolved observations show that the cooling phase in solar flares can be much longer than theoretical models predict. It has not yet been determined whether this is also the case for different subregions within the flare…

Solar and Stellar Astrophysics · Physics 2024-06-21 Malte Bröse , Alexander Warmuth , Taro Sakao , Yang Su

In this work, we analyse coordinated observations spanning chromospheric, TR and coronal temperatures at very high resolution which reveal essential characteristics of thermally unstable plasmas. Coronal rain is found to be a highly…

Solar and Stellar Astrophysics · Physics 2015-06-17 P. Antolin , G. Vissers , T. M. D. Pereira , L. Rouppe van der Voort , E. Scullion