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The coming decade will see the routine use of solar data of unprecedented spatial and spectral resolution, time cadence, and completeness. To capitalize on the new (or soon to be available) facilities such as SDO, ATST and FASR, and the…

Context. Photospheric motions shuffle the footpoints of the strong axial magnetic field that threads coronal loops giving rise to turbulent nonlinear dynamics characterized by the continuous formation and dissipation of field-aligned…

Solar and Stellar Astrophysics · Physics 2012-08-14 R. B. Dahlburg , G. Einaudi , A. F. Rappazzo , M. Velli

We have measured line widths in active region coronal loops in order to determine whether the non-thermal broadening is anisotropic with respect to the magnetic field direction. These non-thermal velocities are caused by unresolved fluid…

Solar and Stellar Astrophysics · Physics 2023-08-09 Michael Hahn , Mahboubeh Asgari-Targhi , Daniel Wolf Savin

Many studies of the solar corona have shown that the observed X-ray luminosity is well correlated with the total unsigned magnetic flux. In this paper we present results from the extensive numerical modeling of active regions observed with…

Astrophysics · Physics 2016-08-30 Harry P. Warren , Amy R. Winebarger

There is considerable observational evidence of implosion of magnetic loop systems inside solar coronal active regions following high energy events like solar flares. In this work, we propose that such collapse can be modeled in three…

Solar and Stellar Astrophysics · Physics 2017-12-27 Aveek Sarkar , Bhargav Vaidya , Soumitra Hazra , Jishnu Bhattacharyya

New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer sub-structures within coronal loop cross sections, in order to…

Solar and Stellar Astrophysics · Physics 2015-06-22 Eamon Scullion , Luc Rouppe van der Voort , Sven Wedemeyer , Patrick Antolin

Coronal loops interconnecting two active regions, called as interconnecting loops (ILs), are prominent large-scale structures in the solar atmosphere. They carry a significant amount of magnetic flux, therefore are considered to be an…

Solar and Stellar Astrophysics · Physics 2018-06-27 Guohui Du , Yao Chen , Chunming Zhu , Chang Liu , Lili Ge , Bing Wang , Chuanyang Li , Haimin Wang

We study the temporal evolution of coronal loops using data from the Solar X-ray Imager (SXI) on board of GOES-12. This instrument allows us to follow in detail the full lifetime of coronal loops. The observed light curves suggest three…

Astrophysics · Physics 2008-11-26 M. C. Lopez Fuentes , J. A. Klimchuk , C. H. Mandrini

The heating of the solar chromosphere and corona to the observed high temperatures, imply the presence of ongoing heating that balances the strong radiative and thermal conduction losses expected in the solar atmosphere. It has been…

It is generally agreed that small impulsive energy bursts called nanoflares are responsible for at least some of the Sun's hot corona, but whether they are the explanation for most of the multi-million degree plasma has been a matter of…

Solar and Stellar Astrophysics · Physics 2015-05-28 Sergio Terzo , Fabio Reale , Marco Miceli , James A. Klimchuk , Ryouhei Kano , Saku Tsuneta

One candidate-model for heating the solar corona is magnetic reconnection that embodies Ohmic dissipation of current sheets. When numerous small-scaled magnetic reconnection occur, then it is possible to heat the corona. Due to the…

Solar and Stellar Astrophysics · Physics 2018-09-19 Charalambos Kanella , Boris V. Gudiksen

High resolution spectral observations of the lower solar atmosphere (chromosphere and transition region) during coronal heating events, in combination with predictions from models of impulsively heated loops, provide powerful diagnostics of…

Solar and Stellar Astrophysics · Physics 2023-11-01 Paola Testa , Helle Bakke , Luc Rouppe van der Voort , Bart De Pontieu

The corona is a layer of hot plasma that surrounds the Sun, traces out its complex magnetic field, and ultimately expands into interplanetary space as the supersonic solar wind. Although much has been learned in recent decades from advances…

Solar and Stellar Astrophysics · Physics 2019-09-11 Steven R. Cranmer , Amy R. Winebarger

We present the results of models of impulsively heated coronal loops using the 1-D hydrodynamic Adaptively Refined Godunov Solver (ARGOS) code. The impulsive heating events (which we refer to as "nanoflares") are modeled by discrete pulses…

Solar and Stellar Astrophysics · Physics 2025-09-01 Therese A. Kucera , James A. Klimchuk , Manuel Luna

We present a study of the temporal evolution of coronal loops in active regions and its implications for the dynamics in coronal loops. We analyzed images of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) at…

Solar and Stellar Astrophysics · Physics 2011-08-09 S. Kamio , H. Peter , W. Curdt , S. K. Solanki

The profiles of emission lines formed in the corona contain information on the dynamics and the heating of the hot plasma. Only recently has data with sufficiently high spectral resolution become available for investigating the details of…

Solar and Stellar Astrophysics · Physics 2015-05-18 H. Peter

Based on observations from the EUV Imaging Spectrometer (EIS) on board Hinode, the existence of a broad distribution of blue and red Dopplershift in active region loops has been revealed; the distribution of Dopplershifts depends on the…

Solar and Stellar Astrophysics · Physics 2017-06-07 S. Regnier , R. W. Walsh

Nanoflares, the basic unit of impulsive energy release may produce much of the solar background emission. Extrapolation of the energy frequency distribution of observed microflares, which follows a power law to lower energies can give an…

Solar and Stellar Astrophysics · Physics 2011-12-22 E. Tajfirouze , H. Safari

The content of coronal material in the quiet Sun is not constant as soft X-ray and high-temperature EUV line observations have shown. New material, probably heated and evaporated from the chromosphere is occasionally injected even in the…

Astrophysics · Physics 2007-05-23 Arnold O. Benz , Sam Krucker

Propagating disturbances are often observed in active region fan-like coronal loops. They were thought to be due to slow mode MHD waves based on some of the observed properties. But the recent studies involving spectroscopy indicate that…

Solar and Stellar Astrophysics · Physics 2015-11-11 S. Mandal , T. Samanta , D. Banerjee , S. Krishna Prasad , L. Teriaca