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We use helioseismic holography to study the association of shallow flows with solar flare activity in about 250 large sunspot groups observed between 2010 and 2014 with the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory.…

Solar and Stellar Astrophysics · Physics 2016-03-16 D. C. Braun

Solar flares, especially the M- and X-class flares, are often associated with coronal mass ejections (CMEs). They are the most important sources of space weather effects, that can severely impact the near-Earth environment. Thus it is…

Solar and Stellar Astrophysics · Physics 2022-12-02 Hewei Zhang , Qin Li , Yanxing Yang , Ju Jing , Jason T. L. Wang , Haimin Wang , Zuofeng Shang

We present the evolution of magnetic nonpotentiality associated with an X-class flare in AR 6919 using a set of MSO (Mees Solar Observatory) magnetograms. The magnetogram data were obtained before and after the flare, using the Haleakala…

Astrophysics · Physics 2009-09-25 Y. -J. Moon , H. S. Yun , G. S. Choe , Y. D. Park , D. L. Mickey

Parametrizations for internal gravity waves in atmospheric models are traditionally subject to a number of simplifications. Most notably, they rely on both neglecting wave propagation and advection in the horizontal direction (single-column…

Fluid Dynamics · Physics 2024-02-28 Georg S. Voelker , Gergely Bölöni , Young-Ha Kim , Günther Zängl , Ulrich Achatz

We use simulations of LSS formation to study the build-up of magnetic fields (MFs) in the ICM. Our basic assumption is that cosmological MFs grow in a MHD amplification process driven by structure formation out of a seed MF present at high…

Astrophysics · Physics 2010-12-09 Klaus Dolag , Dario Grasso , Volker Springel , Igor Tkachev

This paper presents a post hoc analysis of a deep learning-based full-disk solar flare prediction model. We used hourly full-disk line-of-sight magnetogram images and selected binary prediction mode to predict the occurrence of…

Machine Learning · Computer Science 2023-10-10 Chetraj Pandey , Rafal A. Angryk , Manolis K. Georgoulis , Berkay Aydin

A three-dimensional (3D) MHD model is applied to simulate the evolution of a large-scale magnetic field in a barred galaxy possessing a gaseous halo extending to about 2.8 kpc above the galactic plane. As the model input we use a…

Astrophysics · Physics 2009-11-07 K. Otmianowska-Mazur , D. Elstner , M. Soida , M. Urbanik

We present a hidden Markov model (HMM) for discovering stellar flares in light curve data of stars. HMMs provide a framework to model time series data that are not stationary; they allow for systems to be in different states at different…

White-light flares are explosive phenomena accompanied by brightening of continuum from near-ultraviolet to optical, which occur on the Sun and stars. In order to investigate the mechanism of white-light flares, we carried out simultaneous…

With gravity, ionization, and radiation being considered, we perform 2.5D compressible resistive MHD simulations of chromospheric magnetic reconnection using the CIP-MOCCT scheme. The temperature distribution of the quiet-Sun atmospheric…

Solar and Stellar Astrophysics · Physics 2015-03-17 R. L. Jiang , C. Fang , P. F. Chen

Context. Multi-dimensional solar flare simulations have not yet included detailed analysis of the lower atmospheric responses such as down-flowing chromospheric compressions and chromospheric evaporation processes. Aims. We present an…

Solar and Stellar Astrophysics · Physics 2024-02-02 Malcolm Druett , Wenzhi Ruan , Rony Keppens

Filaments are special plasma phenomena embedded in the solar atmosphere, characterized by unique thermodynamic properties and magnetic structures. Magnetohydrodynamic (MHD) simulations are useful to investigate the eruption mechanisms of…

Solar and Stellar Astrophysics · Physics 2025-04-22 Yihua Li , Yang Guo , Jinhan Guo , M. D. Ding , Chun Xia , Rony Keppens

Without any doubt solar flaring loops possess a multi-thread internal structure that is poorly resolved and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause…

Solar and Stellar Astrophysics · Physics 2015-11-04 R. Falewicz , P. Rudawy , K. Murawski , A. K. Srivastava

Recent multi-wavelength observations of M87* \citep{2024A&A...692A.140A} revealed a high-energy $\gamma$-ray flare without a corresponding millimeter counterpart. We present a theoretical polarimetric study to evaluate the presence and…

We perform Differential Emission Measure (DEM) analysis of an M7.7 flare that occurred on 2012 July 19 and was well observed by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory. Using the observational data with…

Solar and Stellar Astrophysics · Physics 2015-06-19 J. Q. Sun , X. Cheng , M. D. Ding

A deep learning network, Long-Short Term Memory (LSTM) network, is used in this work to predict whether the maximum flare class an active region (AR) will produce in the next 24 hours is class $\Gamma$. We considered $\Gamma$ are $\ge M$,…

Solar and Stellar Astrophysics · Physics 2020-05-27 Xiantong Wang , Yang Chen , Gabor Toth , Ward B. Manchester , Tamas I. Gombosi , Alfred O. Hero , Zhenbang Jiao , Hu Sun , Meng Jin , Yang Liu

The distribution of small-scale magnetic fields in stellar photospheres is an important ingredient in our understanding of the magnetism of low mass stars. Their spatial distribution connects the field generated in the stellar interior with…

Solar and Stellar Astrophysics · Physics 2023-06-14 Ekaterina Ilin , Ruth Angus , Rodrigo Luger , Brett M. Morris , Florian U. Jehn

We describe observations of a white-light flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray sources.For…

Of all the activity observed on the Sun, two of the most energetic events are flares and Coronal Mass Ejections (CMEs). Usually, solar active regions that produce large flares will also produce a CME, but this is not always true (Yashiro et…

Solar and Stellar Astrophysics · Physics 2016-04-25 Monica G. Bobra , Stathis Ilonidis

Improving the performance of solar flare forecasting is a hot topic in solar physics research field. Deep learning has been considered a promising approach to perform solar flare forecasting in recent years. We first used the Generative…

Solar and Stellar Astrophysics · Physics 2021-12-15 Zheng Deng , Feng Wang , Hui Deng , Lei Tan , Linhua Deng , Song Feng