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We report on the properties of coronal loop foot-point heating with observations at the highest resolution, from the CRisp Imaging Spectro-Polarimeter (CRISP) located at the Swedish 1-m Solar Telescope (SST) and co-aligned NASA Solar…

Solar and Stellar Astrophysics · Physics 2021-11-24 V. N. Nived , E. Scullion , J. G. Doyle , R. Susino , P. Antolin , D. Spadaro , C. Sasso , S. Sahin , M. Mathioudakis

Recent observations with TRACE reveal that the time delay between the appearance of a cooling loop in different EUV temperature filters is proportional to the loop length, dt_12 ~ L. We model this cooling delay in terms of radiative loss…

Astrophysics · Physics 2009-11-16 Markus J. Aschwanden , C. J. Schrijver , A. R. Winebarger , H. P. Warren

The objectives of the present study is to provide a better physical understanding of the complex inter-relation and evolution of several solar coronal features comprising a double-peak flare, a coronal dimming caused by a CME, a CME-driven…

Solar and Stellar Astrophysics · Physics 2015-06-23 M. S. Madjarska , J. G. Doyle , J. Shetye

We present a model for the intensity of optically thin EUV emission for a plasma atmosphere. We apply our model to the solar corona as observed using the six optically thin EUV channels of the SDO/AIA instrument. The emissivity of the…

Solar and Stellar Astrophysics · Physics 2020-03-31 D. J. Pascoe , A. Smyrli , T. Van Doorsselaere

The study examines the heating profile of hot solar transition region loops, particularly focusing on transient brightenings observed in IRIS 1400{\AA} slit-jaw images. The findings challenge the adequacy of simplistic, singular heating…

Solar and Stellar Astrophysics · Physics 2024-05-15 Shah Mohammad Bahauddin , Stephen J Bradshaw

In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon that can occur when the heating is both highly-stratified and quasi-constant. Unambiguous observational identification of TNE would thus permit to strongly constrain…

Solar and Stellar Astrophysics · Physics 2017-02-08 Clara Froment , Frédéric Auchère , Guillaume Aulanier , Zoran Mikić , Karine Bocchialini , Eric Buchlin , Jacques Solomon

Observational measurements of active region emission measures contain clues to the time-dependence of the underlying heating mechanism. A strongly non-linear scaling of the emission measure with temperature indicates a large amount of hot…

Solar and Stellar Astrophysics · Physics 2015-06-11 Stephen J. Bradshaw , James A. Klimchuk , Jeffrey W. Reep

In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching…

Solar and Stellar Astrophysics · Physics 2015-06-18 A. Petralia , F. Reale , P. Testa , G. Del Zanna

Context: Long-period intensity pulsations were recently detected in the EUV emission of coronal loops, and have been attributed to cycles of plasma evaporation and condensation driven by thermal non-equilibrium (TNE). Numerical simulations…

Solar and Stellar Astrophysics · Physics 2020-02-12 Gabriel Pelouze , Frédéric Auchère , Karine Bocchialini , Clara Froment , Susanna Parenti , Elie Soubrié

Coronal flare emission is commonly observed to decay on timescales longer than those predicted by impulsively-driven, one-dimensional flare loop models. This discrepancy is most apparent during the gradual phase, where emission from these…

Solar and Stellar Astrophysics · Physics 2023-03-01 William Ashfield , Dana Longcope

Coronal loops are the basic structures of the solar transition region and corona. The understanding of physical mechanism behind the loop heating, plasma flows, and filling are still considered a major challenge in the solar physics. The…

Solar and Stellar Astrophysics · Physics 2015-02-24 G. R. Gupta , Durgesh Tripathi , Helen E. Mason

Quasi-periodic propagating intensity disturbances have been observed in large coronal loops in EUV images over a decade, and are widely accepted to be slow magnetosonic waves. However, spectroscopic observations from Hinode/EIS revealed…

Solar and Stellar Astrophysics · Physics 2015-11-04 X. Fang , D. Yuan , T. Van Doorsselaere , R. Keppens , C. Xia

Coronal loops are basic building blocks of solar atmosphere and are observed on various length scales. However, their formation mechanism is still unclear. In this paper, we present the spectroscopic and imaging observations of small-scale…

Solar and Stellar Astrophysics · Physics 2022-04-06 Girjesh R. Gupta , Sushree S. Nayak

A switching-off process very similar to those in real high-voltage self-blast circuit-breakers is emulated in a model chamber to study the arc properties by optical emission spectroscopy. The arc is operated in a chamber filled with SF$_6$…

We investigate the transverse oscillations of a line-tied multi-stranded coronal loop composed of several parallel cylindrical strands. First, the collective fast normal modes of the loop are found with the T-matrix theory. There is a huge…

Solar and Stellar Astrophysics · Physics 2011-02-11 M. Luna , J. Terradas , R. Oliver , J. L. Ballester

Observations of slow magneto-acoustic waves have been demonstrated to possess a number of applications in coronal seismology. Determination of the polytropic index ($\gamma$) is one such important application. Analysing the amplitudes of…

Solar and Stellar Astrophysics · Physics 2018-12-12 S. Krishna Prasad , J. O. Raes , T. Van Doorsselaere , N. Magyar , D. B. Jess

Aims. We investigate the synthetic observational signatures from numerical models of coronal heating in an arcade to determine what features are associated with such heating, and what tools can be used to identify them. Methods. We consider…

Solar and Stellar Astrophysics · Physics 2021-12-11 Lianne Fyfe , Thomas Howson , Ineke De Moortel

Recent coronal loop modeling has emphasized the importance of combining both Coulomb collisions and turbulent scattering to characterize field-aligned thermal conduction, which invokes a hybrid loop model. In this work we generalize the…

Solar and Stellar Astrophysics · Physics 2024-03-05 Y. Dai , J. J. Xiang , M. D. Ding

Plasma ions heating (especially minor heavy ions preferential heating) in fast solar wind and solar corona is an open question in space physics. However, Alfv\'en waves have been always considered as a candidate of energy source for corona…

Plasma Physics · Physics 2021-08-17 Peng He

Previous studies have found that coronal loops have a nearly uniform thickness, which seems to disagree with the characteristic expansion of active region magnetic fields. This is one of the most intriguing enigmas in solar physics. We here…

Astrophysics · Physics 2009-11-13 M. C. Lopez Fuentes , J. A. Klimchuk , P. Demoulin