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New instruments sensitive to chromospheric radiation at X-ray, UV, Visible, IR, and sub-mm wavelengths have become available that significantly enhance our ability to understand the bi-directional flow of energy through the chromosphere. We…

Solar and Stellar Astrophysics · Physics 2022-07-27 Adam R. Kobelski , Lucas A. Tarr , Sarah A. Jaeggli , Nicholas Luber , Harry P. Warren , Sabrina L. Savage

The solar atmosphere is filled with clusters of hot small-scale loops commonly known as Coronal Bright Points (CBPs). These ubiquitous structures stand out in the Sun by their strong X-ray and/or extreme-ultraviolet (EUV) emission for hours…

Solar and Stellar Astrophysics · Physics 2024-06-14 D. Nóbrega-Siverio , F. Moreno-Insertis , K Galsgaard , K. Krikova , L. Rouppe van der Voort , R. Joshi , M. S. Madjarska

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

Nanoflares are regarded as one of the major mechanisms of magnetic energy release and coronal heating in the solar outer atmosphere. We conduct a statistical study on the response of the chromosphere and transition region to nanoflares, as…

Solar and Stellar Astrophysics · Physics 2023-03-29 Kyuhyoun Cho , Paola Testa , Bart De Pontieu , Vanessa Polito

We study properties of waves of frequencies above the photospheric acoustic cut-off of $\approx$5.3 mHz, around four active regions, through spatial maps of their power estimated using data from Helioseismic and Magnetic Imager (HMI) and…

Solar and Stellar Astrophysics · Physics 2015-06-05 S. P. Rajaguru , S. Couvidat , Xudong Sun , K. Hayashi , H. Schunker

Magnetohydrodynamic (MHD) waves have been considered as energy sources for heating the solar chromosphere and the corona. Although MHD waves have been observed in the solar atmosphere, there are a lack of quantitative estimates on the…

Solar and Stellar Astrophysics · Physics 2016-11-01 Ryuichi Kanoh , Toshifumi Shimizu , Shinsuke Imada

The distribution and evolution of photospheric magnetic field in sunspots, plages and network, and variations in their relative flux content, play key roles in radial velocity (RV) fluctuations observed in Sun-as-a-star spectra.…

Solar and Stellar Astrophysics · Physics 2023-09-12 Anisha Sen , S. P. Rajaguru

A magneto-hydrostatic model is constructed with spectropolarimetric properties close to those of solar photospheric magnetic bright points. Results of solar radiative magneto-convection simulations are used to produce the spatial structure…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Shelyag , M. Mathioudakis , F. P. Keenan , D. B. Jess

It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona low-FIP elements, such as Fe, Si,…

Solar and Stellar Astrophysics · Physics 2016-06-22 Harry P. Warren , David H. Brooks , George A. Doschek , Uri Feldman

Recent observations of the solar photosphere revealed the presence of elongated filamentary bright structures inside sunspot umbrae, called umbral filaments (UFs). These features differ in morphology, magnetic configuration, and evolution…

Solar and Stellar Astrophysics · Physics 2019-07-31 S. L. Guglielmino , P. Romano , B. Ruiz Cobo , F. Zuccarello , M. Murabito

We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet Sun (QS) at disc centre, and the brightness at 214 nm, 300 nm, 313 nm, 388 nm, 397 nm, and at 525.02 nm. To this end we…

Solar and Stellar Astrophysics · Physics 2017-04-05 F. Kahil , T. L. Riethmüller , S. K. Solanki

Solar activity can be witnessed in the form of sunspots and active regions, where the magnetic field is enhanced by up to a factor 1000 as compared to that of the quiet Sun. In addition, solar activity manifests itself in terms of flares,…

Solar and Stellar Astrophysics · Physics 2025-07-25 Gottfried Mann , Frédéric Schuller

Dynamics of hot chromospheric plasma of solar flares is a key to understanding of mechanisms of flare energy release and particle acceleration. A moderate M1.0 class flare of 12 June, 2014 (SOL2014-06-12T21:12) was simultaneously observed…

Searches for small exoplanets around solar-type stars are limited by stellar physical variability. While chromospheric variability is well studied, observing, modeling. and understanding the much smaller fluctuations in photospheric…

Solar and Stellar Astrophysics · Physics 2024-07-03 Dainis Dravins , Hans-Günter Ludwig

Moving magnetic features (MMFs) are small-size magnetic elements that are seen to stream out from sunspots, generally during their decay phase. Several observational results presented in the literature suggest them to be closely related to…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Criscuoli , D. Del Moro , F. Giannattasio , B. Viticchié , F. Giorgi , I. Ermolli , F. Zuccarello , F. Berrilli

In the current analysis, we use spectroscopic observations of the quiet-Sun made by IRIS instrument, and investigate wave propagation. We analyze various spectral lines formed in different atmospheric layers such as the photosphere,…

Solar and Stellar Astrophysics · Physics 2024-03-18 Kartika Sangal , A. K. Srivastava , P. Kayshap , Ding Yuan , E. Scullion

From Doppler velocity maps of active regions constructed from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft we observe large areas of outflow (20-50 km/s) that can persist for at least a…

Astrophysics · Physics 2009-11-13 G. A. Doschek , H. P. Warren , J. T. Mariska , K. Muglach , J. L. Culhane , H. Hara , T Watanabe

{Chromospheric evaporation is a key process in solar flares that has extensively been investigated using the spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings…

Solar and Stellar Astrophysics · Physics 2015-06-16 Q. M. Zhang , H. S. Ji

The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First we concentrate on the detailed description of the magnetic field evolution…

Solar and Stellar Astrophysics · Physics 2016-08-10 D. Utz , J. C. del Toro Iniesta , L. R. Bellot Rubio , J. Jurčák , V. Martínez Pillet , S. K. Solanki , W. Schmidt

Stellar activity is the major roadblock on the path to finding true Earth-analogue planets with the Doppler technique. Thus, identifying new indicators that better trace magnetic activity (i.e. faculae and spots) is crucial to aid in…

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