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Coronal mass ejections (CMEs) are the eruptions of magnetised plasma from the Sun and are considered the main driver of adverse space weather events. Hence, undrstanding its formation process, particularly the magnetic topology, is critical…

Solar and Stellar Astrophysics · Physics 2025-02-26 Jinhan Guo , Y. W. Ni , B. Schmieder , Y. Guo , C. Xia , P. Devi , R. Chandra , S. Poedts , R. Joshi , Y. H. Zhou , H. T. Li , P. F. Chen

Magnetic flux ropes (MFRs) are fundamental magnetic structures in solar eruptions, whose formation is generally attributed to (1) the emergence of subsurface flux tubes or (2) flux cancellation driven by photospheric horizontal flows and…

Solar and Stellar Astrophysics · Physics 2025-12-17 Can Wang , Takaaki Yokoyama , Feng Chen , Chen Xing , Mingde Ding , Zekun Lu

Recent Sunrise/IMaX observations have revealed the existence of supersonic magnetic flows. Our aim is to determine the origin of such flows by using realistic MHD simulations. We simulate cancellation and emergence of magnetic flux through…

Solar and Stellar Astrophysics · Physics 2015-06-22 S. Danilovic , R. H. Cameron , S. K. Solanki

The hydrogen Lyman lines ( 91.2 nm < lambda < 121.6 nm) are significant contributors to the radiative losses of the solar chromosphere, and are enhanced during flares. We have shown previously that the Lyman lines observed by the Extreme…

Solar and Stellar Astrophysics · Physics 2018-08-08 Stephen A Brown , Lyndsay Fletcher , Graham S Kerr , Nicolas Labrosse , Adam F Kowalski , Jaime De La Cruz Rodríguez

Solar spicules are plasma jets observed in the interface region between the visible solar surface and the corona. At any given time, there are millions of spicules present all over the Sun. While various models attempt to elucidate their…

Solar and Stellar Astrophysics · Physics 2024-10-17 Kartav Kesri , Sahel Dey , Piyali Chatterjee , Robertus Erdelyi

Small-scale explosive events or microflares occur throughout the chromospheric network of the Sun. They are seen as sudden bursts of highly Doppler shifted spectral lines of ions formed at temperatures in the range 2x10^4 - 5x10^5 K. They…

Astrophysics · Physics 2015-06-24 D. E. Innes , G. Toth

We investigate high resolution spectroscopic and imaging observations from the CRisp Imaging SpectroPolarimeter (CRISP) instrument to study the dynamics of chromospheric spicule type events. It is widely accepted that chromospheric fine…

Solar and Stellar Astrophysics · Physics 2021-12-30 Juie Shetye , Erwin Verwichte , Marco Stangalini , J. G. Doyle

We present a method of conducting data-driven simulations of solar active regions and flux emergence with the MURaM radiative magnetohydrodynamics (MHD) code. The horizontal electric field derived from the full velocity and magnetic…

Solar and Stellar Astrophysics · Physics 2023-06-14 Feng Chen , Mark C. M. Cheung , Matthias Rempel , Georgios Chintzoglou

We performed a 3D radiative MHD simulation of the solar atmosphere. This simulation shows a jet-like feature that shows similarities to the type II spicules observed for the first time with Hinode. Rapid Blueshifted Events (RBEs) on the…

Context: Flux emergence in the solar atmosphere is a complex process that causes a release of magnetic energy as heat and acceleration of solar plasma at a variety of spatial scales. Methods: We analysed imaging spectropolarimetric data…

We analyze recent high resolution photospheric small-scale dynamo simulations that were computed with the MURaM radiative MHD code. We focus the analysis on newly forming downflow lanes in exploding granules since they show how weakly…

Solar and Stellar Astrophysics · Physics 2018-06-27 Matthias Rempel

Solar flares emanate from solar active regions hosting complex and strong bipolar magnetic fluxes. Estimating the probability of an active region to flare and defining reliable precursors of intense flares is an extremely challenging task…

We track and investigate from white-light data taken with the Wide-field Instrument for Solar PRobe (WISPR) aboard Parker Solar Probe (PSP), localized density enhancements, reflecting small-scale magnetic structures belonging to a…

Solar and Stellar Astrophysics · Physics 2024-08-21 G. M. Cappello , M. Temmer , A. Vourlidas , C. Braga , P. C. Liewer , J. Qiu , G. Stenborg , A. Kouloumvakos , A. M. Veronig , V. Bothmer

We present high-cadence observations and simulations of the solar photosphere, obtained using the Rapid Oscillations in the Solar Atmosphere imaging system and the MuRAM magneto-hydrodynamic code, respectively. Each dataset demonstrates a…

Solar and Stellar Astrophysics · Physics 2015-06-03 D. B. Jess , S. Shelyag , M. Mathioudakis , P. H. Keys , D. J. Christian , F. P. Keenan

High-resolution imaging observations from the Hinode spacecraft in the CaII H line are employed to study the dynamics of the chromosphere above a sunspot. We find that umbral flashes and other brightenings produced by the oscillation are…

Astrophysics · Physics 2011-02-11 H. Socas-Navarro , S. W. McIntosh , R. Centeno , A. G. de Wijn , B. W. Lites

We take a broad look at the problem of identifying the magnetic solar causes of space weather. With the lackluster performance of extrapolations based upon magnetic field measurements in the photosphere, we identify a region in the near UV…

The specification of the upper atmosphere strongly relies on solar proxies that can properly reproduce the solar energetic input in the UV. Whilst the microwave flux at 10.7 cm (also called F10.7 index) has been routinely used as a solar…

Solar and Stellar Astrophysics · Physics 2014-02-18 Thierry Dudok de Wit , Sean Bruinsma , Kiyoto Shibasaki

The observation of propagating magneto-hydrodynamic kink waves in magnetic structures and measurement of their properties (amplitude, phase speed) can be used to diagnose the plasma conditions in the neighbourhood of the magnetic structure…

Solar and Stellar Astrophysics · Physics 2016-08-03 R J Morton

It is not fully understood why some solar filaments erupt while others do not. Those that do typically undergo a slow rise followed by an acceleration phase, though this transition requires further investigation. Erupting prominences have…

Solar and Stellar Astrophysics · Physics 2026-03-25 Dion Donné , Yuhao Zhou , Hebe Cremades , Rony Keppens

The model of stochastic acceleration of particles by turbulence has been successful in explaining many observed features of solar flares. Here we demonstrate a new method to obtain the accelerated electron spectrum and important…

Solar and Stellar Astrophysics · Physics 2015-05-18 Vahe Petrosian , Qingrong Chen