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The solar chromosphere and transition region (TR) form an interface between the Sun's surface and its hot outer atmosphere. Here most of the non-thermal energy that powers the solar atmosphere is transformed into heat, although the detailed…

Transient brightenings in the transition region of the Sun have been studied for decades and are usually related to magnetic reconnection. Recently, absorption features due to chromospheric lines have been identified in transition region…

Solar and Stellar Astrophysics · Physics 2015-09-23 Limei Yan , Hardi Peter , Jiansen He , Hui Tian , Lidong Xia , Linghua Wang , Chuanyi Tu , Lei Zhang , Feng Chen , Krzysztof Barczynski

Two of the most important features of the solar atmosphere are its hot, smooth coronal loops and the concentrations of magnetic shear, known as filament channels, that reside above photospheric polarity inversion lines (PILs). The shear…

Solar and Stellar Astrophysics · Physics 2016-06-30 Kalman J. Knizhnik

One of the most important features in the solar atmosphere is magnetic network and its rela- tionship with the transition region (TR), and coronal brightness. It is important to understand how energy is transported into the corona and how…

Solar and Stellar Astrophysics · Physics 2018-03-21 Ehsan Tavabi

We analyzed a coronal loop observed with the Normal Incidence Spectrometer (NIS), which is part of the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The measured Doppler shifts and proper…

Astrophysics · Physics 2009-11-10 C. Gontikakis , G. J. D. Petrie , H. C. Dara , K. Tsinganos

Spectral lines allow us to probe the thermodynamics of the solar atmosphere, but the shape of a single spectral line may be similar for different thermodynamic solutions. Multiline analyses are therefore crucial, but computationally…

Solar and Stellar Astrophysics · Physics 2021-05-19 Brandon Panos , Lucia Kleint , Sviatoslav Voloshynovskiy

Coronal loops generally trace magnetic lines of force in the upper solar atmosphere. Understanding the loop morphology and its temporal evolution has implications for coronal heating models that rely on plasma heating due to reconnection at…

Solar and Stellar Astrophysics · Physics 2025-01-29 B. Ram , L. P. Chitta , S. Mandal , H. Peter , F. Plaschke

Spectral observations of the solar transition region (TR) and corona show broadening of spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant (5-30 km/s) and…

Solar and Stellar Astrophysics · Physics 2017-10-19 Bart De Pontieu , Scott McIntosh , Juan Martinez-Sykora , Hardi Peter , Tiago Pereira

Using extreme-ultraviolet images, we recently proposed a new and alternative formation mechanism for coronal rain along magnetically open field lines due to interchange magnetic reconnection. In this paper we report coronal rain at…

Solar and Stellar Astrophysics · Physics 2020-12-16 Leping Li , Hardi Peter , Lakshmi Pradeep Chitta , Hongqiang Song

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

In the present paper, we use Si IV 1393.755 \AA\ spectral line observed by the Interface Region Imaging Spectrograph (IRIS) in the quiet-Sun to determine physical nature of the solar transition region (TR) oscillations. We analyze the…

Solar and Stellar Astrophysics · Physics 2022-10-12 Kartika Sangal , A. K. Srivastava , P. Kayshap , T. J Wang , J. J. González-Avilés , Abhinav Prasad

The solar atmosphere was traditionally represented with a simple one-dimensional model. Over the past few decades, this paradigm shifted for the chromosphere and corona that constitute the outer atmosphere, which is now considered a dynamic…

The plasma contributing to emission from the Sun between the cool chromosphere ($\le 10^4$K) and hot corona ($\ge 10^6$K) has been subjected to many different interpretations. Here we look at the magnetic structure of this transition region…

Solar and Stellar Astrophysics · Physics 2021-06-23 Philip G. Judge

We investigate various dynamic processes including magnetic reconnection, chromospheric evaporation, and coronal rain draining in two limb solar flares through imaging and spectroscopic observations from the Interface Region Imaging…

Solar and Stellar Astrophysics · Physics 2022-08-17 Ke Yu , Y. Li , Jie Hong , De-Chao Song , M. D. Ding

Coronal loops are the basic structures of the solar transition region and corona. The understanding of physical mechanism behind the loop heating, plasma flows, and filling are still considered a major challenge in the solar physics. The…

Solar and Stellar Astrophysics · Physics 2015-02-24 G. R. Gupta , Durgesh Tripathi , Helen E. Mason

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

The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that…

In this study, we investigate motions in the hot plasma above the flare loops during the 2017 September 10 X8.2 flare event. We examine the region to the south of the main flare arcade, where there is data from the Interface Region Imaging…

Solar and Stellar Astrophysics · Physics 2021-01-06 Katharine K. Reeves , Vanessa Polito , Bin Chen , Giselle Galan , Sijie Yu , Wei Liu , Gang Li

The composition of plasma in the solar corona is characterised by the First Ionisation Potential (FIP) bias, and is thought to be the result of a ponderomotive force acting in the chromosphere to separate ionised from neutral plasma.…

Solar and Stellar Astrophysics · Physics 2026-03-06 Éabha Power , David M. Long , Teodora Mihailescu , Laura A. Hayes

Spicules have been proposed as significant contributors to the mass and energy balance of the corona. While previous observations have provided a glimpse of short-lived transient brightenings in the corona that are associated with spicules,…

Solar and Stellar Astrophysics · Physics 2017-10-19 Bart De Pontieu , Ineke De Moortel , Juan Martinez-Sykora , Scott McIntosh