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How the solar corona is heated to high temperatures remains an unsolved mystery in solar physics. In the present study we analyse observations of 50 whole active-region loops taken with the Extreme-ultraviolet Imaging Spectrometer (EIS) on…

Solar and Stellar Astrophysics · Physics 2017-06-28 Haixia Xie , Maria S. Madjarska , Bo Li , Zhenghua Huang , Lidong Xia , Thomas Wiegelmann , Hui Fu , Chaozhou Mou

Solar flares are widely accepted to be powered by magnetic reconnection that involves complex dynamics in various scales. The flare supra-arcade and loop-top region, directly impacted by fast reconnection downflows, contains a wealth of…

Solar and Stellar Astrophysics · Physics 2025-05-27 Tingyu Gou , Katharine K. Reeves

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

We present an analysis of off-limb cool flare loops observed by SDO/AIA during the gradual phase of SOL2017-09-10T16:06 X8.2-class flare. In the EUV channels starting from the 335 {\AA} one, cool loops appear as dark structures against the…

Solar and Stellar Astrophysics · Physics 2020-06-24 Petr Heinzel , Pavol Schwartz , Juraj Lörinčík , Július Koza , Sonja Jejčič , David Kuridze

Quasi-constant heating at the footpoints of loops leads to evaporation and condensation cycles of the plasma: thermal non-equilibrium (TNE). This phenomenon is believed to play a role in the formation of prominences and coronal rain.…

Solar and Stellar Astrophysics · Physics 2015-08-27 Clara Froment , Frédéric Auchère , Karine Bocchialini , Eric Buchlin , Chloé Guennou , Jacques Solomon

Recent observations from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode have shown that low density areas on the periphery of active regions are characterized by strong blue-shifts at 1 MK. These Doppler shifts have been…

Solar and Stellar Astrophysics · Physics 2015-05-19 Ignacio Ugarte-Urra , Harry P. Warren

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional…

Solar and Stellar Astrophysics · Physics 2014-04-04 Wei Liu , Qingrong Chen , Vahe' Petrosian

Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in…

Solar and Stellar Astrophysics · Physics 2014-11-20 Harry P. Warren , Amy R. Winebarger , David H. Brooks

Quasi-periodic intensity disturbances propagating upward along the coronal structure have been extensively studied using EUV imaging observations from SOHO/EIT and TRACE. They were interpreted as either slow mode magnetoacoustic waves or…

Solar and Stellar Astrophysics · Physics 2012-01-26 Tongjiang Wang , Leon Ofman , Joseph M. Davila

In this paper, we present a detailed morphological, kinematic, and thermal analysis of two homologous magnetic flux ropes (MFRs) from NOAA 11515 on 2012 July 8--9. The study is based on multi-wavelength and dual-perspective imaging…

Solar and Stellar Astrophysics · Physics 2021-12-15 De-Chao Song , Y. Li , Y. Su , M. D. Ding , W. Q. Gan

With the aim of studying AR fan loops using Hinode/EIS and SDO/AIA, we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why their images look very similar despite the fact…

Solar and Stellar Astrophysics · Physics 2015-05-27 David H. Brooks , Harry P. Warren , Peter R. Young

We exploit the high spatial resolution and high cadence of the Interface Region Imaging Spectrograph (IRIS) to investigate the response of the transition region and chromosphere to energy deposition during a small flare. Simultaneous…

Solar and Stellar Astrophysics · Physics 2016-09-28 Harry P. Warren , Jeffrey W. Reep , Nicholas A. Crump , Paulo J. A. Simoes

Nanoflares are impulsive energy releases by magnetic reconnection in the braided coronal magnetic field, which is a potential mechanism for heating the corona. However, there are still sporadic observations of the interchange of braiding…

Solar and Stellar Astrophysics · Physics 2023-11-01 Y. Bi , J. J. Yang , Y. Qin , Z. P. Qiang , J. C. Hong , B. Yang , Z. Xu , H. Liu , K. F. Ji

How structures, e.g., magnetic loops, in the upper atmosphere, i.e., the transition region and corona, are heated and sustained is one of the major unresolved issues in solar and stellar physics. Various theoretical and observational…

Solar and Stellar Astrophysics · Physics 2023-06-07 Leping Li , Hui Tian , Huadong Chen , Hongqiang Song , Zhenyong Hou , Xianyong Bai , Kaifan Ji , Yuanyong Deng

This work is prompted by the evidence of sharply peaked emission measure distributions in active stars, and by the claims of isothermal loops in solar coronal observations, at variance with the predictions of hydrostatic loop models with…

Astrophysics · Physics 2009-11-10 Paola Testa , Giovanni Peres , Fabio Reale

We present a study of the frequency of transient brightenings in the core of solar active regions as observed in the Fe XVIII line component of AIA/SDO 94 A filter images. The Fe XVIII emission is isolated using an empirical correction to…

Solar and Stellar Astrophysics · Physics 2015-06-18 Ignacio Ugarte-Urra , Harry P. Warren

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

Using data obtained by the EUV Imaging Spectrometer (EIS) onboard Hinode, we have per- formed a survey of obvious and persistent (without significant damping) Doppler shift oscillations in the corona. We have found mainly two types of…

Solar and Stellar Astrophysics · Physics 2012-10-31 Hui Tian , Scott W. McIntosh , Tongjiang Wang , Leon Ofman , Bart De Pontieu , Davina E. Innes , Hardi Peter

This paper presents a detailed study of chromospheric evaporation using the EUV Imaging Spectrometer (EIS) onboard Hinode in conjunction with HXR observations from RHESSI. The advanced capabilities of EIS were used to measure Doppler shifts…

Solar and Stellar Astrophysics · Physics 2015-05-13 Ryan O. Milligan , Brian R. Dennis

EUV imaging observations from several space missions (SOHO/EIT, TRACE, and SDO/AIA) have revealed a presence of propagating intensity disturbances in solar coronal loops. These disturbances are typically interpreted as slow magnetoacoustic…

Solar and Stellar Astrophysics · Physics 2018-01-24 Elena Provornikova , Leon Ofman , Tongjiang Wang
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