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Solar extreme-ultraviolet (EUV) waves generally refer to large-scale disturbances propagating outward from sites of solar eruptions in EUV imaging observations. Using the recent observations from the Atmospheric Imaging Assembly (AIA) on…

Solar and Stellar Astrophysics · Physics 2022-11-09 Zheng Sun , Hui Tian , P. F. Chen , Shuo Yao , Zhenyong Hou , Hechao Chen , Linjie Chen

We investigate the properties and relationship between Doppler-velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvenic and compressive waves, respectively.…

Solar and Stellar Astrophysics · Physics 2025-03-21 Michael Hahn , Xiangrong Fu , Stefan J. Hofmeister , Yifan Huang , Alexandros Koukras , Daniel Wolf Savin

EIT waves are a wavelike phenomenon propagating outward from the coronal mass ejection (CME) source region, with expanding dimmings following behind. We present a spectroscopic study of an EIT wave/dimming event observed by Hinode/EIS.…

Solar and Stellar Astrophysics · Physics 2010-09-17 F. Chen , M. D. Ding , P. F. Chen

We present the first SDO AIA observations of a global coronal EUV disturbance (so-called "EIT wave") revealed in unprecedented detail. The disturbance observed on 2010 April 8 exhibits two components: one diffuse pulse superimposed on which…

Solar and Stellar Astrophysics · Physics 2014-04-04 Wei Liu , Nariaki V. Nitta , Carolus J. Schrijver , Alan M. Title , Theodore D. Tarbell

Oscillations of coronal loops in the Sun have been reported in both imaging and spectral observations at the onset of flares. Images reveal transverse oscillations, whereas spectra detect line-of-sight velocity or Doppler-shift…

Solar and Stellar Astrophysics · Physics 2015-05-27 Danica Tothova , Davina Innes , Guillermo Stenborg

An expansion of cross-sectional area directly impacts the mass flow along a coronal loop, and significantly alters the radiative and hydrodynamic evolution of that loop as a result. Previous studies have found that an area expansion from…

Solar and Stellar Astrophysics · Physics 2024-03-20 Jeffrey W. Reep , Roger B. Scott , Sherry Chhabra , John Unverferth , Kalman J. Knizhnik

We report a quasi-periodic pulsation (QPP) event simultaneously detected from the spatial displacements of coronal loop at both EUV images and microwave emission during the preflare phase of a C1.1 flare on 2016 March 23. Using the motion…

Solar and Stellar Astrophysics · Physics 2020-04-22 Dong Li , Ying Li , Lei Lu , Qingmin Zhang , Zongjun Ning , Sergey Anfinogentov

Coronal loop observations have existed for many decades yet the precise shape of these fundamental coronal structures is still widely debated since the discovery that they appear to undergo negligible expansion between their footpoints and…

Solar and Stellar Astrophysics · Physics 2021-09-29 Thomas Williams , Robert W. Walsh , Huw Morgan

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

Coronal loops are plasma structures in the solar atmosphere with temperatures reaching millions of Kelvin, shaped and sustained by the magnetic field. However, their morphology and fundamental nature remain subjects of debate. By studying…

Solar and Stellar Astrophysics · Physics 2026-01-14 N. Vasantharaju , H. Peter , L. P. Chitta , S. Mandal

QFP wave trains in the corona have been studied intensively in the past decade, thanks to the full-disk, high spatiotemporal resolution, and wide-temperature coverage observations taken by the SDO/AIA. In AIA observations, QFP wave trains…

Solar and Stellar Astrophysics · Physics 2022-02-23 Yuandeng Shen , Xinping Zhou , Yadan Duan , Zehao Tang , Chengrui Zhou , Song Tan

By employing a local two-fluid theory, we investigate an obliquely propagating electromagnetic instability in the lower hybrid frequency range driven by cross-field current or relative drifts between electrons and ions. The theory…

Astrophysics · Physics 2007-05-23 Hantao Ji , Russell Kulsrud , William Fox , Masaaki Yamada

Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding ~ 50…

Solar and Stellar Astrophysics · Physics 2015-06-18 Spiros Patsourakos , James Klimchuk , Peter Young

Quasi-periodic, propagating fast mode magnetosonic waves in the corona were difficult to observe in the past due to relatively low instrument cadences. We report here evidence of such waves directly imaged in EUV by the new SDO AIA…

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

Employing Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) multi-wavelength images, we have presented coronal condensations caused by magnetic reconnection between a system of open and closed solar coronal loops. In this…

Solar and Stellar Astrophysics · Physics 2019-01-16 Leping Li , Jun Zhang , Peter Hardi , Lakshmi Pradeep Chitta , Jiangtao Su , Hongqiang Song , Chun Xia , Yijun Hou

In a recent work Grappin et al. [1] have shown that low- frequency movements can be transmitted from one footpoint to the other along a magnetic loop, thus mimicking a friction effect of the corona on the photosphere, and invalidating the…

Solar and Stellar Astrophysics · Physics 2014-11-20 A. Verdini , R. Grappin , M. Velli

Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which…

Upflows at the edges of active regions (ARs) are studied by spatially and temporally combining multi-instrument observations obtained with EIS/Hinode, AIA and HMI/SDO and IBIS/NSO, to derive their plasma parameters. This information is used…

Solar and Stellar Astrophysics · Physics 2015-11-18 K. Vanninathan , M. S. Madjarska , K. Galsgaard , Z. Huang , J. G. Doyle

Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler velocity…

Solar and Stellar Astrophysics · Physics 2015-06-22 A. K. Srivastava , P. Konkol , K. Murawski , B. N. Dwivedi , A. Mohan