Abstract Solar eruptions are well-recognized as major drivers of space weather but what causes them remains an open question. Here we show how eruption is initiated in a non-potential magnetic flux-emerging region using magnetohydrodynamic modelling driven directly by solar magnetograms. Our model simulates the coronal field following long-duration quasi-static evolution to its fast eruption. The morphology resembles set extreme ultraviolet images for whole process. Study suggests that this...

Current magnetohydrodynamic (MHD) simulations of the initiation solar eruptions are still commonly carried out with idealized magnetic field models, whereas realistic coronal prior to can possibly be reconstructed from observable photospheric field. Using a nonlinear force-free extrapolation sigmoid eruption in AR 11283 as initial condition MHD model, we successfully simulate process event, is confirmed by remarkable resemblance SDO/AIA observations. Analysis pre-eruption reveals that...

Magnetic reconnection is a multi-faceted process of energy conversion in astrophysical, space and laboratory plasmas that operates at microscopic scales but has macroscopic drivers consequences. Solar flares present key for its study, leaving imprints the physics radiation spectra allowing evolution to be imaged, yet full observational characterization remains elusive. Here we combine high resolution imaging spectral observations confined solar flare multiple wavelengths with...

We present a comprehensive study of the formation and eruption an active region (AR) sigmoid in AR 11283. To follow quasi-static evolution coronal magnetic field, we reconstruct time sequence static fields using recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis compared with observations suggests following scenario for region. Initially, new bipole emerges into negative polarity preexisting bipolar AR, forming null-point topology...

We study the physical mechanism of a major X-class solar flare that occurred in super NOAA active region (AR) 12192 using data-driven numerical magnetohydrodynamic (MHD) modeling complemented with observations. With evolving magnetic fields observed at surface as bottom boundary input, we drive an MHD system to evolve self-consistently correspondence realistic coronal evolution. During two-day time interval, modeled field has been slowly stressed by photospheric evolution,which gradually...

This work is devoted to the construction of a data-driven model for study dynamic evolution global corona that can respond continuously changing photospheric magnetic field. The consists surface flux transport (SFT) and three-dimensional (3D) magnetohydrodynamic (MHD) coronal model. SFT employed produce time-varying self-consistent synchronic snapshots field as input drive our 3D numerical AMR–CESE–MHD on an overset grid Yin–Yang overlapping structure. are coupled through boundary condition...

The magnetic flux rope is among the most fundamental configurations in plasma. Although its presence after solar eruptions has been verified by spacecraft measurements near Earth, formation on Sun remains elusive, yet critical to understanding a broad spectrum of phenomena. Here we study dynamic during classic two-ribbon flare. Its feet are identified unambiguously with conjugate coronal dimmings completely enclosed irregular bright rings, which originate and expand outward from far ends...

Abstract Magnetic flux ropes (MFRs) are thought to be the central structures of solar eruptions, and their ideal MHD instabilities can trigger eruption. Here we performed a study all MFR configurations that lead major flares, either eruptive or confined, from 2011 2017 near disk center. The coronal magnetic field is reconstructed observed magnetograms, based on twist distribution, identified MFR, which defined as coherent group lines winding an axis with more than one turn. It found 90%...

Abstract Three-dimensional magnetic topology is crucial to understanding the explosive release of energy in corona during solar flares. Much attention has been given pre-flare identify candidate sites reconnection, yet it unclear how reconnection and its attendant topological changes shape eruptive structure evolves eruption. Here we employed a realistic, data-constrained magnetohydrodynamic simulation study evolving for an X9.3 flare that occurred on 2017 September 6. The successfully...

A hybrid three-dimensional (3D) MHD model for solar wind study is proposed in the present paper with combined grid systems and solvers. The computational domain from Sun to Earth space decomposed into near-Sun off-Sun domains, which are respectively constructed a Yin–Yang overset system Cartesian adaptive mesh refinement (AMR) coupled connection interface overlapping region between domains. space-time conservation element solution method used domain, while Harten–Lax–Leer employed domain....

Solar filament are commonly thought to be supported in magnetic dips, particular, of flux ropes (FRs). In this Letter, from the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation coronal FR that supports large-scale intermediate between an active region and weak polarity region. This result is first current NLFFF extrapolations with presence FRs limited relatively small-scale filaments close sunspots along main inversion line (PIL)...

Abstract For realistic magnetohydrodynamics (MHD) simulation of the solar active region (AR), two types capabilities are required. The first is capability to calculate bottom-boundary electric field vector, with which observed magnetic can be reconstructed through induction equation. second a proper boundary treatment limit size sub-Alfvénic region. We developed (1) practical inversion method yield solar-surface vector from temporal evolution three components data maps, and (2)...

ABSTRACT Solar eruptions are explosive disruption of coronal magnetic fields, and often launch mass ejections into the interplanetary space. Intriguingly, many solar fail to escape from Sun, prevailing theory for such failed eruption is based on ideal magnetohydrodynamic (MHD) instabilities flux rope (MFR); that is, an MFR runs kink instability erupts but cannot reach height torus instability. Here, numerical MHD simulation, we present a new model in which reconnection plays leading role...

ABSTRACT There is a heated debate regarding the specific roles played by ideal magnetohydrodynamic (MHD) instability and magnetic reconnection in triggering solar eruptions. In context of pre-existing flux rope (MFR) before an eruption, it widely believed that MHD instability, particular, torus responsible for driving while reconnection, as invoked wake erupting MFR, plays secondary role. Here, we present new numerical model which eruption MFR primarily triggered driven reconnection. this...

Due to the absence of direct measurement, magnetic field in solar corona is usually extrapolated from photosphere a numerical way. At moment, nonlinear force-free (NLFFF) model dominates physical models for extrapolation low corona. Recently, we have developed new NLFFF with MHD relaxation reconstruct coronal field. This method based on CESE–MHD conservation-element/solution-element (CESE) spacetime scheme. In this paper, report application CESE–MHD–NLFFF code Solar Dynamics...

Abstract This paper investigates the statistical features of equatorial plasma bubbles (EPBs) using airglow images from 2012 to 2014 a ground‐based network four imagers in region China. It is found that (1) EPBs mainly occur during 21:00–00:00 local time (LT) equinoxes. There an asymmetry occurrence rates between March (June) and September equinoxes (December solstices). (2) Most groups two six depletions. The distance adjacent EPB depletions ~100–700 km, average 200–300 km. zonal extension...

Solar flares and coronal mass ejections (CMEs) are the most powerful explosions in Sun. They major sources of potentially destructive space weather conditions. However, possible causes their initiation remain controversial. By using high resolution data observed by NST BBSO, supplemented Dynamics Observatory (SDO) observations, we present unusual observations a small-scale emerging flux rope near large sunspot, whose eruption produced an M-class flare ejection. The presence was indicated...

For a better understanding of magnetic field in the solar corona and dynamic activities such as flares coronal mass ejections, it is crucial to measure time-evolving accurately estimate energy. Recently, new modeling technique called data-driven model, which time evolution driven by sequence photospheric velocity maps, has been developed revealed dynamics flare-productive active regions. Here we report on first qualitative quantitative assessment different models using flux emergence...

We present a new implementation of the MHD relaxation method for reconstruction nearly force-free coronal magnetic field from photospheric vector magnetogram. A numerical scheme is proposed to solve full equations by using spacetime conservation-element and solution-element method. The bottom boundary condition prescribed in similar way as stress-and-relax method, changing transverse incrementally match magnetogram, other boundaries computational box are set nonreflecting conditions....

The magnetic field in the solar corona is usually extrapolated from a photospheric vector magnetogram using nonlinear force-free (NLFFF) model. NLFFF extrapolation needs considerable effort to be devoted its numerical realization. In this paper, we present new implementation of magnetohydrodynamics (MHD) relaxation method for extrapolation. magnetofrictional approach, which introduced speeding MHD system, realized first time by spacetime conservation-element and solution-element scheme. A...

We apply a data-driven magnetohydrodynamics (MHD) model to investigate the three-dimensional (3D) magnetic field of NOAA active region (AR) 11117 around time C-class confined flare that occurred on 2010 October 25. The MHD model, based spacetime conservation-element and solution-element scheme, is designed focus evolution consider simplified solar atomsphere with finite plasma β. Magnetic vector-field data derived from observations at photosphere inputted directly constrain model. Assuming...

We carry out a comprehensive investigation comparing the three-dimensional magnetic field restructuring, flare energy release, and helioseismic response of two homologous flares, 2011 September 6 X2.1 (FL1) 7 X1.8 (FL2) flares in NOAA AR 11283. In our analysis, (1) twisted flux rope (FR) collapses onto surface at speed 1.5 km s−1 after partial eruption FL1. The FR then gradually grows to reach higher altitude again 3 fuller FL2. Also, FL2 shows larger decrease flux-weighted centroid...

Abstract Solar flares are often associated with coronal eruptions, but there confined ones without even for some X-class flares. How such large occurred and why they still not well understood. Here we studied a X2.2 flare in NOAA Active Region 12673 on 2017 September 6. It exhibits two episodes of brightening rather complex, atypical ribbons. Based topology analysis the extrapolated magnetic field, revealed that is two-step reconnection process during flare. Prior to flare, flux rope (MFR)...