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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

Outflows perpendicular to the guide field are believed to be a possible signature of magnetic reconnection in the solar corona and specifically a way to detect the occurrence of ubiquitous small-angle magnetic reconnection. The aim of this…

Solar and Stellar Astrophysics · Physics 2025-03-05 G. Cozzo , P. Pagano , F. Reale , P. Testa , A. Petralia , J. Martinez-Sykora , V. Hansteen , B. De Pontieu

In recent decades our understanding of solar active regions (ARs) has improved substantially due to observations made with better angular resolution and wider spectral coverage. While prior AR observations have shown that these structures…

Propagating slow waves in coronal loops exhibit a damping which depends upon the frequency of the waves. In this study we aim to investigate the relationship of the damping length (L$_d$) with the frequency of the propagating wave. We…

Solar and Stellar Astrophysics · Physics 2016-03-23 Sudip Mandal , Norbert Magyar , Ding Yuan , Tom Van Doorsselaere , Dipankar Banerjee

Quasi-periodic disturbances have been observed in the outer solar atmosphere for many years now. Although first interpreted as upflows (Schrijver et al. (1999)), they have been widely regarded as slow magnetoacoustic waves, due to observed…

Solar and Stellar Astrophysics · Physics 2015-06-05 G. Kiddie , I. De Moortel , G. Del Zanna , S. W. McIntosh , I. Whittaker

Context: Flux emergence in the solar atmosphere is a complex process that causes a release of magnetic energy as heat and acceleration of solar plasma at a variety of spatial scales. Methods: We analysed imaging spectropolarimetric data…

In coronal loop modeling, it is commonly assumed that the loops are semi-circular with a uniform cross-sectional area. However, observed loops are rarely semi-circular, and extrapolations of the magnetic field show that the field strength…

Solar and Stellar Astrophysics · Physics 2022-07-20 Jeffrey W. Reep , Ignacio Ugarte-Urra , Harry P. Warren , Will T. Barnes

We developed Long Short-Term Memory (LSTM) models to predict the formation of active regions (ARs) on the solar surface. Using the Doppler shift velocity, the continuum intensity, and the magnetic field observations from the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2024-09-27 Spiridon Kasapis , Irina N. Kitiashvili , Alexander G. Kosovichev , John T. Stefan

We perform direct numerical simulations of an externally driven two-dimensional magnetohydrodynamic system over extended periods of time to simulate the dynamics of a transverse section of a solar coronal loop. A stationary and large-scale…

Astrophysics · Physics 2009-10-30 Pablo Dmitruk , Daniel O. Gomez

We present a boundary data-driven magneto-hydrodynamic (MHD) simulation of the 2011-02-15 coronal mass ejection (CME) event of Active Region (AR) NOAA 11158. The simulation is driven at the lower boundary with an electric field derived from…

Solar and Stellar Astrophysics · Physics 2024-09-27 Yuhong Fan , Maria D. Kazachenko , Andrey N. Afanasyev , George H. Fisher

Observational and theoretical evidence suggests that coronal heating is impulsive and occurs on very small cross-field spatial scales. A single coronal loop could contain a hundred or more individual strands that are heated…

Astrophysics · Physics 2009-11-13 J. A. Klimchuk , S. Patsourakos , P. J. Cargill

Solar flares emanate from solar active regions hosting complex and strong bipolar magnetic fluxes. Estimating the probability of an active region to flare and defining reliable precursors of intense flares is an extremely challenging task…

We present observations of electron energization in magnetic reconnection outflows during the pre-impulsive phase of solar flare SOL2012-07-19T05:58. During a time-interval of about 20 minutes, starting 40 minutes before the onset of the…

Solar and Stellar Astrophysics · Physics 2019-03-06 Marina Battaglia , Eduard P. Kontar , Galina Motorina

Determining the preferred spatial location of the energy input to solar coronal loops would be an important step forward towards a more complete understanding of the coronal heating problem. Following on from Sarkar & Walsh (2008) this…

Solar and Stellar Astrophysics · Physics 2009-07-22 Aveek Sarkar , Robert W Walsh

The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometres per…

Extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) are providing new insights into the early phase of CME evolution. Observations now show the ejection of magnetic flux…

Solar and Stellar Astrophysics · Physics 2014-09-05 Paolo Pagano , Duncan H. Mackay , Stefaan Poedts

The heating of ions and electrons due to turbulent dissipation plays a crucial role in the thermodynamics of the solar wind and other plasma environments. Using magnetic field and thermal plasma observations from the first two perihelia of…

Solar and Stellar Astrophysics · Physics 2023-04-12 Niranjana Shankarappa , Kristopher G. Klein , Mihailo M Martinović

We statistically estimate the conversion rate of the energy released during an active-region transient brightening to Doppler motion and thermal and non-thermal energies. We used two types of datasets for the energy estimation and detection…

Solar and Stellar Astrophysics · Physics 2021-09-29 Toshiki Kawai , Shinsuke Imada

We present a comparison of the Solar Dynamics Observatory (SDO) analysis of NOAA Active Region (AR) 11158 and numerical simulations of flux-tube emergence, aiming to investigate the formation process of this flare-productive AR. First, we…

Solar and Stellar Astrophysics · Physics 2014-03-18 S. Toriumi , Y. Iida , K. Kusano , Y. Bamba , S. Imada

Recent imaging observations of EUV line emissions have shown evidence for frequent flare-like events in a majority of the pixels in quiet regions of the solar corona. The changes in coronal emission measure indicate impulsive heating of new…

Astrophysics · Physics 2009-11-07 Arnold O. Benz , Sam Krucker