Abstract Solar flares, driven by prompt release of free magnetic energy in the solar corona 1,2 , are known to accelerate a substantial portion (ten per cent or more) 3,4 available electrons high energies. Hard X-rays, produced high-energy accelerated flare 5 require ambient density for their detection. This restricts observed volume denser regions that do not necessarily sample entire 6 . Here we report evolving spatially resolved distributions thermal and non-thermal derived from microwave...

Magnetic energy release in a solar flare Solar flares are bright flashes and associated eruptions of plasma from the Sun that thought to be powered by violent rearrangement magnetic fields near sunspots. Fleishman et al. observed with microwave interferometer, allowing them map field corona monitor how it changed during flare. They found large drop local strength over 2 minutes, releasing enough power entire Determining origin this will help predict strong future may their potential space...

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, inhomogeneous turbulent corona strongly affects propagation emitted waves, so decoupling intrinsic properties emitting source from effects radio-wave has long been major challenge in physics. Here we report quantitative spatial and frequency characterization burst fine structures observed with LOw Frequency Array (LOFAR), an instrument high time resolution that also permits imaging at scales much...

Abstract We report the first science results from newly completed Expanded Owens Valley Solar Array (EOVSA), which obtained excellent microwave (MW) imaging spectroscopy observations of SOL2017-09-10, a classic partially occulted solar limb flare associated with an erupting flux rope. This event is also well-covered by Reuven Ramaty High Energy Spectroscopic Imager ( RHESSI ) in hard X-rays (HXRs). present overview this focusing on MW and HXR data, both high-energy nonthermal electrons, we...

Abstract We analyze high-resolution observations of an X-1.0 white-light flare, triggered by a filament eruption, on 2022 October 2. The full process formation and subsequent eruption was captured in the H α passband Visible Imaging Spectrograph (VIS) board Goode Solar Telescope (GST) within its center field view. White-light emissions appear flare ribbons following ribbon brightening. GST Broadband Filter Imager data show that continuum intensity, as compared to nearby quiet-Sun area, has...

Abstract Magnetic reconnection plays a crucial role in powering solar flares, production of energetic particles, and plasma heating. However, where the magnetic reconnections occur, how released energy is transported, it converted to other forms remain unclear. Here we report recurring bidirectional outflows located within large-scale sheet observed extreme-ultraviolet emission scattered white light during post-impulsive gradual phase X8.2 flare on 2017 September 10. Each originates from...

Recurrent and homologous jets were observed to the west edge of active region NOAA 11513 at boundary a coronal hole. We find two kinds cancellations between opposite polarity magnetic fluxes, inducing generation recurrent jets. First, satellite spot continuously collides with pre-existing field causes solar Second, moving features, which emerge near sunspot penumbra, pass through ambient plasma eventually collide field. Among these jets, blowout jet that occurred around 21:10 UT is...

Magnetic reconnection, the central engine that powers explosive phenomena throughout Universe, is also perceived as one of principal mechanisms for accelerating particles to high energies. Although various signatures magnetic reconnection have been frequently reported, observational evidence links particle acceleration directly site has rare, especially space plasma environments currently inaccessible $\textit{in situ}$ measurements. Here we utilize broadband radio dynamic imaging...

Abstract We report microwave spectral imaging observations of an erupting magnetic flux rope during the early impulsive phase X8.2-class limb flare on 2017 September 10, obtained by Expanded Owens Valley Solar Array. A few days prior to eruption, when viewed against disk, appeared as a reverse S-shaped dark filament along polarity inversion line. During exhibited “hot channel” structure in extreme ultraviolet and soft X-ray passbands sensitive ∼10 MK plasma. The central portion was nearly...

In this study, we investigate motions in the hot plasma above flare loops during 2017 September 10 X8.2 event. We examine region to south of main arcade, where there is data from Interface Region Imaging Spectrograph (IRIS), and Extreme ultraviolet Spectrometer (EIS) on Hinode. find that are initial blue shifts 20--60 km/s observed Fe XXI line IRIS XXIV EIS, locations these move southward along arcade over course about min. The cadence allows us follow evolution flows, at each location an...

Magnetic reconnection is the key mechanism for energy release in solar eruptions, where high-temperature emission primary diagnostic investigating plasma properties during process. Non-thermal broadening of lines has been observed both current sheet (CS) and flare loop-top regions by UV spectrometers, but its origin remains unclear. In this work, we use a recently developed three-dimensional magnetohydrodynamic (MHD) simulation to model magnetic standard geometry reveal highly dynamic flows...

The heating mechanisms of solar white-light flares remain unclear. We present an X1.0 flare on 2022 October 2 (SOL2022-10-02T20:25) observed by the Chinese \ha\ Solar Explorer (CHASE) that provides two-dimensional spectra in visible light for full disk with a seeing-free condition. shows prominent enhancement $\sim$40\% photospheric \fe\ line at 6569.2 \AA, and nearby continuum also exhibits maximum $\sim$40\%. For near 6173 \AA\ from Helioseismic Magnetic Imager (HMI) board Dynamics...

Aims: This work aims to identify the mechanism driving pulsations in hard X-ray (HXR) and microwave emission during solar flares. Here, by using combined HXR observations from Solar Orbiter/STIX EOVSA we investigate an X1.3 GOES class flare, 2022-03-30T17:21:00, which displays on timescales evolving ~ 7 s impulsive phase 35 later flare. Methods: The temporal, spatial spectral evolution of flare are analysed. Images reconstructed for individual peaks fitting is performed at high cadence...

Aims. The aim of this work is to identify the mechanism driving pulsations in hard X-ray (HXR) and microwave emission during solar flares. Using combined HXR observations from Solar Orbiter/STIX EOVSA, we investigate an X1.3 GOES class flare, 2022-03-30T17:21:00, which displays on timescales evolving ∼7 s impulsive phase ∼35 later flare. Methods. We analysed temporal, spatial, spectral evolution reconstructed images for individual peaks performed fitting at high cadence throughout first...

Abstract In this article, we present the application of weighted horizontal gradient magnetic field (WG M ) flare prediction method to three-dimensional (3D) extrapolated configurations 13 flaring solar active regions (ARs). The main aim is identify an optimal height range, if any, in interface region between photosphere and lower corona, where onset time capability WG best exploited. prediction, by means method, achieved earlier than at photospheric level. 3D structures, based on potential...

Abstract During the 24th solar cycle, Fermi Large Area Telescope (LAT) has observed a total of 27 flares possessing delayed γ -ray emission, including exceptionally well-observed flare and coronal mass ejection (CME) on 2017 September 10. Based Fermi/LAT data, we plot, for first time, maps possible sources >100 MeV emission 10 event. The long-lasting is localized under CME core. spectrum exhibits intermittent changes in implying that more than one source high-energy protons was formed...

Abstract Quasi-periodic pulsations (QPPs) are frequently detected in solar and stellar flares, but the underlying physical mechanisms still to be ascertained. Here, we show microwave QPPs during a flare originating from quasi-periodic magnetic reconnection at current sheet. They appear as two vertically detached closely related sources with brighter ones located loops weaker along stretched Although brightness temperatures of differ greatly, they vary phase periods about 10–20 s 30–60 s. The...

Abstract The acceleration and transport of energetic electrons during solar flares is one the outstanding topics in physics. Recent X-ray radio imaging spectroscopy observations have provided diagnostics distribution nonthermal suggested that, certain flare events, are primarily accelerated loop top likely experience trapping and/or scattering effects. By combining focused particle equation with magnetohydrodynamic (MHD) simulations flares, we present a macroscopic model that naturally...

Abstract Radio bursts from nearby active M-dwarfs have been frequently reported and extensively studied in solar or planetary paradigms. Whereas, their substructures fine structures remain rarely explored despite potential significance diagnosing the plasma magnetic field properties of star. Such studies past limited by sensitivity radio telescopes. Here we report inspiring results high time-resolution observations a known flare star AD Leo with Five-hundred-meter Aperture Spherical...

In this paper, we present an automated system, which has the capability to catch and track solar limb prominences based on observations from extreme-ultraviolet (EUV) 304 Å passband. The characteristic parameters their evolution, including height, position angle, area, length, brightness, are obtained without manual interventions. By applying system STEREO-B/SECCHI/EUVI data during 2007 April–2009 October, obtain a total of 9477 well-tracked catalog these events available online. A detailed...

Solar radio type III bursts are believed to be the most sensitive signature of near-relativistic electron beam propagation in corona. A solar IIIb-III pair burst with fine frequency structures, observed by Low Frequency Array (LOFAR) high temporal ($\sim10$ ms) and spectral (12.5 kHz) resolutions at 30 - 80 MHz, is presented. The observations show that consists many striae, which have a scale about 0.1 MHz both fundamental (plasma) harmonic (double plasma) emission. We investigate effects...

Abstract Where and how flares efficiently accelerate charged particles remains an unresolved question. Recent studies revealed that a “magnetic bottle” structure, which forms near the bottom of large-scale reconnection current sheet above flare arcade, is excellent candidate for confining accelerating particles. However, further understanding its role requires linking various observational signatures to underlying coupled plasma particle processes. Here we present first study combining...