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Flares are intense explosions on the solar and stellar surfaces, and solar flares are sometimes accompanied by filament or prominence eruptions. Recently, a large filament eruption associated with a superflare on a solar-type star EK Dra…

Solar and Stellar Astrophysics · Physics 2024-01-10 Kai Ikuta , Kazunari Shibata

Two of the central problems in our understanding of the solar chromosphere are how the upper chromosphere is heated and what drives spicules. Estimates of the required chromospheric heating, based on radiative and conductive losses suggest…

Solar and Stellar Astrophysics · Physics 2016-10-05 C. S. Brady , T. D. Arber

We investigate the thermal, kinematic and magnetic structure of small-scale heating events in an emerging flux region (EFR). We use high-resolution multi-line observations (including Ca II 8542~\AA, Ca II K, and Fe I 6301~\AA line pair) of…

Solar and Stellar Astrophysics · Physics 2023-09-14 Rahul Yadav , Maria D. Kazachenko , Andrey N. Afanasyev , Jaime de la Cruz Rodríguez , Jorrit Leenaarts

Solar microflares are ubiquitous in the solar corona, yet their driving mechanisms remain a subject of ongoing debate. Using high-resolution coronal observations from the Solar Orbiter's Extreme Ultraviolet Imager (EUI), we identified about…

Solar and Stellar Astrophysics · Physics 2025-03-17 Qingmei Wang , Yi Bi , Hongfei Liang , Jiayan Yang , Liufan Gong

Solar flares and coronal mass ejections (CMEs) are among the most energetic events in the solar system, impacting the near-Earth environment. Flare productivity is empirically known to be correlated with the size and complexity of active…

Solar and Stellar Astrophysics · Physics 2017-06-16 Chloé Guennou , Etienne Pariat , Nicole Vilmer , James E. Leake

In this review many of the well known tools for the analysis of Complex systems are used in order to study the global coupling of the turbulent convection zone with the solar atmosphere where the magnetic energy is dissipated explosively.…

Solar and Stellar Astrophysics · Physics 2016-11-03 Loukas Vlahos , Heinz Isliker

Plasma upflows with a Doppler shift exceeding -10 km/s at active region (AR) boundaries are considered potential sources of the nascent slow solar wind. We investigate the driving mechanisms of a pair of coronal upflow regions on the…

The formation and properties of accretion discs and circumstellar material in Algol-type systems is not very well understood. In order to study the underlying physics of these structures, we have calculated synthetic Halpha spectra of TT…

Astrophysics · Physics 2009-11-10 Jan Budaj , Mercedes T. Richards , Brendan Miller

We model the solar radial velocity (RV) signal induced by faculae, the dominant contributor to RV variability in Sun-like stars. We use a representative case of a facular patch transiting the visible solar disk as the Sun rotates to…

Stellar activity remains one of the primary challenges in the detection and characterization of low-mass exoplanets, as it can induce radial velocity (RV) variations that mask or mimic planetary signals. Identifying reliable activity…

We present the application of the data-driven branch of the MURaM code to the extensively studied flare-productive active region 11158. We refine the hybrid model strategy, which was described in the earlier paper of this series, to model…

Solar and Stellar Astrophysics · Physics 2026-04-03 Feng Chen

Solar flares are efficient particle accelerators with a large fraction of released magnetic energy (10-50%) converted into energetic particles such as hard X-ray producing electrons. This energy transfer process is not well constrained,…

Solar and Stellar Astrophysics · Physics 2023-04-12 Morgan Stores , Natasha L. S. Jeffrey , James A. McLaughlin

Recent high-resolution solar observations have unveiled the presence of small-scale loop-like structures in the lower solar atmosphere, often referred to as unresolved fine structures, low-lying loops, and miniature hot loops. These…

Solar and Stellar Astrophysics · Physics 2025-03-14 Annu Bura , Tanmoy Samanta , Alphonse Sterling , Yajie Chen , Jayant Joshi , Vasyl Yurchyshyn , Ronald L. Moore

The motions of small-scale magnetic flux elements in the solar photosphere can provide some measure of the Lagrangian properties of the convective flow. Measurements of these motions have been critical in estimating the turbulent diffusion…

Solar and Stellar Astrophysics · Physics 2018-02-27 Piyush Agrawal , Mark P. Rast , Milan Gosic , Luis R. Bellot Rubio , Matthias Rempel

We use coordinated observations with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1-m Solar Telescope (SST) to identify the disk counterpart of type II spicules in upper-chromospheric and transition region (TR)…

Solar and Stellar Astrophysics · Physics 2015-03-04 L. Rouppe van der Voort , B. De Pontieu , T. M. D. Pereira , M. Carlsson , V. Hansteen

We recently reported extremely rapid changes in chromospheric fine structure observed using the IBIS instrument in the red wing of H alpha. Here, we examine data obtained during the same observing run (August 7 2010), of a mature active…

Solar and Stellar Astrophysics · Physics 2015-06-18 Isabel Lipartito , Philip Judge , Kevin Reardon , Gianna Cauzzi

The transport of energetic particles such as Cosmic Rays is governed by the properties of the plasma being traversed. While these properties are rather poorly known for galactic and interstellar plasmas due to the lack of in situ…

Solar and Stellar Astrophysics · Physics 2014-06-03 Tobias Wiengarten , Jens Kleimann , Horst Fichtner , Patrick Kühl , Andreas Kopp , Bernd Heber , Ralf Kissmann

Solar active regions (ARs) are often surrounded by dark large areas of reduced emission compared to the quiet Sun, observed at various wavelengths corresponding to chromosphere, transition region (TR) and corona, and known as Dark Halos…

Using numerical simulations, we study the formation and dynamics of post-flare loops in a local region of the solar atmosphere. The MHD equations rule the post-flare structures' dynamic evolution, including space-dependent magnetic…

Solar and Stellar Astrophysics · Physics 2024-02-15 Mauricio González-Servín , J. J. González-Avilés

We present unprecedented high resolution H-alpha observations, obtained with the Swedish 1-m Solar Telescope, that, for the first time, spatially and temporally resolve dynamic fibrils in active regions on the Sun. These jet-like features…

Astrophysics · Physics 2008-11-26 B. De Pontieu , V. H. Hansteen , L. Rouppe van der Voort , M. van Noort , M. Carlsson
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