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The EUI instrument on the Solar Orbiter spacecraft has obtained the most stable, high-resolution images of the solar corona from its orbit with a perihelion near 0.4 AU. A sequence of 360 images obtained at 17.1 nm, between 25-Oct-2022…

Solar and Stellar Astrophysics · Physics 2023-09-12 Philip G. Judge

High-resolution H$\alpha$ observations indicate that filaments consist of an assembly of thin threads. In quiescent filaments, the threads are generally short, whereas in active region filaments, the threads are generally long. In order to…

Solar and Stellar Astrophysics · Physics 2015-06-18 Y. H. Zhou , P. F. Chen , Q. M. Zhang , C. Fang

We use a combination of analytical theory, numerical simulation, and data analysis to study the propagation of acoustic waves along coronal loops. We show that the intensity perturbation of a wave depends on a number of factors, including…

Astrophysics · Physics 2009-11-10 J. A. Klimchuk , S. E. M. Tanner , I. De Moortel

Waves have long been thought to contribute to the heating of the solar corona and the generation of the solar wind. Recent observations have demonstrated evidence of quasi-periodic longitudinal disturbances and ubiquitous transverse wave…

Solar and Stellar Astrophysics · Physics 2015-06-16 J. Threlfall , I. De Moortel , S. W. McIntosh , C. Bethge

Context: Transverse loop oscillations and loop contractions are commonly associated with solar flares, but the two types of motion have traditionally been regarded as separate phenomena. Aims: We present an observation of coronal loops…

Solar and Stellar Astrophysics · Physics 2015-08-26 Alexander J. B. Russell , Paulos J. A. Simoes , Lyndsay Fletcher

A significant impediment to solving the coronal heating problem is that we currently only observe active region (AR) loops in their cooling phase. Previous studies showed that the evolution of cooling loop densities and apex temperatures…

Solar and Stellar Astrophysics · Physics 2024-01-10 David H. Brooks , Jeffrey W. Reep , Ignacio Ugarte-Urra , John E. Unverferth , Harry P. Warren

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions…

The heating of the outer solar atmospheric layers, i.e., the transition region and corona, to high temperatures is a long standing problem in solar (and stellar) physics. Solutions have been hampered by an incomplete understanding of the…

Evolution of a coronal loop in response to an impulsive energy release is numerically modelled. It is shown that the loop density evolution curves exhibit quasi-periodic perturbations with the periods given approximately by the ratio of the…

Astrophysics · Physics 2009-11-10 V. M. Nakariakov , D. Tsiklauri , A. Kelly , T. D. Arber , M. J. Aschwanden

Employing Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) multi-wavelength images, we report the coronal condensation during the magnetic reconnection (MR) between a system of open and closed coronal loops. Higher-lying…

Solar and Stellar Astrophysics · Physics 2018-09-05 Leping Li , Jun Zhang , Hardi Peter , Lakshmi Pradeep Chitta , Jiangtao Su , Chun Xia , Hongqiang Song , Yijun Hou

I report on observations of a set of magnetic loops above a region with late-phase flux emergence taken by IRIS, Hinode and SDO. The loop system consists of many transition region loop threads with size of 5--12\arcsec\ in length and…

Solar and Stellar Astrophysics · Physics 2019-01-09 Zhenghua Huang

Recurrent and propagating intensity perturbations are frequently observed in extreme ultraviolet (EUV) channels along coronal fan loops above sunspots, and these perturbations are suggested to be slow magnetoacoustic waves. Numerous studies…

Solar and Stellar Astrophysics · Physics 2025-02-26 Junwei Zhao , Tongjiang Wang , Ruizhu Chen

Context. Slow waves in solar coronal loops are strongly damped. The current theory of damping by thermal conduction cannot explain some observational features.\n Aims. We investigate the propagation of slow waves in a coronal loop built up…

Solar and Stellar Astrophysics · Physics 2024-01-19 Tom Van Doorsselaere , S. Krishna Prasad , Vaibhav Pant , Dipankar Banerjee , Alan Hood

We analyze and model an M1.0 flare observed by SDO/AIA and Hinode/EIS to investigate how flare loops are heated and evolve subsequently. The flare is composed of two distinctive loop systems observed in EUV images. The UV 1600 \AA emission…

Solar and Stellar Astrophysics · Physics 2015-06-11 Y. Li , J. Qiu , M. D. Ding

Coronal loops, seen in solar coronal images, are believed to represent emission from magnetic flux tubes with compact cross-sections. We examine the 3D structure of plasma above an active region in a radiative magnetohydrodynamic simulation…

Solar and Stellar Astrophysics · Physics 2022-03-09 A. Malanushenko , M. C. M. Cheung , C. E. DeForest , J. A. Klimchuk , M. Rempel

Active region EUV loops are believed to trace a subset of magnetic field lines through the corona. Malanushenko et al. (2009) proposed a method, using loop images and line-of-sight photospheric magnetograms, to infer the three-dimensional…

Solar and Stellar Astrophysics · Physics 2021-05-27 Marika I. McCarthy , Dana W. Longcope , Anna Malanushenko

We present here one of the first high resolution spectroscopic observations of coronal rain, performed with the CRISP instrument at the Swedish Solar Telescope. This work constitutes the first attempt to assess the importance of coronal…

Solar and Stellar Astrophysics · Physics 2015-06-03 Patrick Antolin , Luc Rouppe van der Voort

Coronal loops reveal crucial information about the nature of both coronal magnetic fields and coronal heating. The shape of the corresponding flux tube cross section and how it varies with position are especially important properties. They…

Solar and Stellar Astrophysics · Physics 2020-07-31 James A. Klimchuk , Craig E. DeForest

In this study we report detailed observations of magnetic environment at four footpoints of two warm coronal loops observed on 5 May 2016 in NOAA AR 12542 (Loop I) and 17 Dec 2015 in NOAA AR 12470 (Loop II). These loops were connecting a…

Solar and Stellar Astrophysics · Physics 2019-03-29 Seray Şahin , Vasyl Yurchyshyn , Pankaj Kumar , Ali Kilcik , Kwangsu Ahn , Xu Yang

The relationships among coronal loop structures at different temperatures is not settled. Previous studies have suggested that coronal loops in the core of an active region are not seen cooling through lower temperatures and therefore are…

Solar and Stellar Astrophysics · Physics 2011-02-11 Ignacio Ugarte-Urra , Harry P. Warren , David H. Brooks