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When in situ solar energetic electron (SEE) events are closely associated with nonthermal flares, the escaping electron population is frequently observed to be much smaller than the nonthermal-radiation-emitting population near the solar surface. If a single accelerated population drives both signatures, the physical mechanism causing this severe deficit of upward-propagating electrons remains poorly understood. Focusing on one of the 2022 November 10–12 SEE events associated with recurrent solar jets and interplanetary type III radio bursts, we present a new, combined microwave–X-ray analysis using the Expanded Owens Valley Solar Array and the Spectrometer/Telescope for Imaging X-rays on board Solar Orbiter. For the first time for such an event, this synergy enables spatially resolved diagnostics over a broad energy spectrum of the near-Sun energetic electrons, complemented by in situ measurements made by spacecraft at multiple heliocentric longitudes and distances. Consistent with earlier results based on in situ and X-ray data, our results show that only 0.1%–1% of energetic electrons escape into interplanetary space. Crucially, the new microwave spectral imaging analysis suggests that energetic electrons are strongly concentrated in a compact region just above a miniflare arcade at the base of the jet spire and that their number density decreases by at least 2 orders of magnitude in the direction of the jet spire away from this region. This steep gradient, revealed by the microwave diagnostics, points to efficient local acceleration and trapping in the region analogous to the above-the-loop-top “magnetic bottle” region in major eruptive flares, allowing only a small fraction of electrons to access open magnetic field lines and enter interplanetary space. 

Abstract We present FlareDB, a database that provides comprehensive magnetic field information, ultraviolet/extreme ultraviolet (UV/EUV) emissions, and white light continuum images for solar active regions (ARs) associated with 151 significant flares from May 2010 to May 2025. The data, sourced from the Solar Dynamics Observatory (SDO) via the Joint Science Operations Center (JSOC), were processed with SunPy and stored in standardized JSOC FITS format. FlareDB includes all M5.0 and larger flares within 50° of the solar disk center. Key features include (1) Atmospheric Imaging Assembly (AIA) AR patches in Helioprojective Cartesian(HPC) and Lambert Cylindrical Equal-Area (CEA) projections, aligned with corresponding HMI magnetogram patches; (2) quick-look movies with uniform value ranges that ensure consistent visualization, maintain data uniformity, and enhance readiness for machine learning studies; (3) a supplementary web interface that allows the entire dataset of a flare to be downloaded for large flare analysis. One of FlareDB’s primary objectives is to support scientists in predicting and understanding the onset of solar eruptions, including flares and coronal mass ejections. The data set is machine-learning ready for this purpose. 

Abstract The southward component of the interplanetary magnetic field, often originating from solar coronal mass ejections (CMEs), plays a crucial role in driving geomagnetic storms. Accurate prediction of the flux rope orientation of CMEs as they arrive at Earth requires a clear understanding of how the orientation of magnetic flux ropes evolves from the solar corona to 1 au. In this study, we investigated six geoeffective CMEs, initiated either from active regions (ARs; three events) or quiet-Sun (QS) filament eruptions (three events). The orientation prior to the eruption is determined by the eruptive filament or the magnetic flux rope near the solar surface. During the CME propagation away from the Sun, the graduated cylindrical shell model and the Grad–Shafranov technique are used to estimate the orientation of the CME magnetic field structure. Our results show that the orientation of flux ropes associated with QS eruptions did not change from the Sun to 1 au. For three rotating events initiated from ARs, the direction of rotation remains consistent during the propagation from the Sun to 1 au. The trend indicates that the heliospheric current sheet has a relatively limited influence on these events. For rotating events, the direction of rotation basically follows the prediction of Lynch’s model. 

Abstract Solar active region 11283 produced an X2.1 flare associated with a solar eruption on 2011 September 6. Observations revealed a preflare sigmoidal structure and a circular flare ribbon surrounding the typical two-ribbon structure, along with remote brightenings located at a considerable distance from the main flare site. To interpret these observations in terms of the dynamics of the three-dimensional coronal magnetic field, we conducted data-constrained magnetohydrodynamic simulations. Using a nonlinear force-free field as the initial condition, we reconstructed a realistic preflare magnetic environment, capturing a sheared sigmoid above the polarity inversion line surmounted by a fan–spine structure. Our simulations revealed that reconnection between the sigmoidal field, the adjacent fan–dome field lines, and the neighboring large loops facilitated the transfer of magnetic twist and led to the formation of a large magnetic flux rope (MFR). This transfer and propagation of twist are clearly visible throughout the MFR. As reconnection progresses, the entire fan–spine structure expands along with the evolving MFR. A notable outcome of the simulation is that the footpoints of the newly formed MFR align closely with the observed circular flare ribbon and the remote brightening region. Our findings suggest that a large MFR formed during the X2.1 flare, providing a coherent explanation for the observed phenomena. 

Abstract Solar eruptions, including flares and coronal mass ejections (CMEs), have a significant impact on Earth. Some flares are associated with CMEs, and some flares are not. The association between flares and CMEs is not always obvious. In this study, we propose a new deep learning method, specifically a hybrid neural network (HNN) that combines a vision transformer with long short-term memory, to predict associations between flares and CMEs. HNN finds spatio-temporal patterns in the time series of line-of-sight magnetograms of solar active regions collected by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and uses the patterns to predict whether a flare projected to occur within the next 24 hr will be eruptive (i.e., CME-associated) or confined (i.e., not CME-associated). Our experimental results demonstrate the good performance of the HNN method. Furthermore, the results show that magnetic flux cancellation in polarity inversion line regions may well play a role in triggering flare-associated CMEs, a finding consistent with the literature. 

Abstract We investigated minifilament (MF) eruptions (MFEs) near coronal hole (CH) boundaries to explore their role in coronal dynamics and their potential contributions to the solar wind. Using high-resolution Hαimages from the 1.6 m Goode Solar Telescope at Big Bear Solar Observatory and Atmospheric Imaging Assembly 193 Å extreme ultraviolet (EUV) data from Solar Dynamics Observatory, we analyzed 28 MFE events over 7.5 hr of observation spanning 5 days. The three largest MF eruptions triggered distinct coronal responses: two consecutive MFEs produced a small-scale eruptive coronal ejection, while the other generated a jetlike brightening. Furthermore, the 25 smaller-scale MFEs were associated with localized brightenings in coronal bright points. These findings suggest that MFs play a significant role in transferring mass and magnetic flux to the corona, particularly within CH regions. We found a certain trend that the size of MFEs is correlated with the EUV emissions. In addition, we observed magnetic flux cancellation associated with MFEs. However, except for a few of the largest MFEs, quantitative analysis of magnetic field evolution is beyond the capability of the data. These results underscore the importance of MFEs in the dynamic coupling between the chromosphere and corona, highlighting their potential role in shaping heliospheric structures. 

Abstract We present the first joint high-resolution observations of small-scale EUV jets using Solar Orbiter (SolO)’s Extreme Ultraviolet Imager and High Resolution Imager (EUI/HRI_EUV) and Hαimaging from the Visible Imaging Spectrometer installed on the 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory. These jets occurred on 2022 October 29 around 19:10 UT in a quiet Sun region, and their main axis aligns with the overarching magnetic structure traced by a cluster of spicules. However, they develop a helical morphology, while the Hαspicules maintain straight, linear trajectories elsewhere. Alongside the spicules, thin, elongated red- and blueshifted Hαfeatures appear to envelope the EUV jets, which we tentatively call sheath flows. The EUI jet moving upward at a speed of ∼110 km s⁻¹is joined by a strong Hαredshift at ∼20 km s⁻¹to form bidirectional outflows lasting ∼2 minutes. Using AI-assisted differential emission measure analysis of SolO’s Full Sun Imager, we derived total energy of the EUV jet as ∼1.9 × 10²⁶erg with 87% in thermal energy and 13% in kinetic energy. The parameters and morphology of this small-scale EUV jet are interpreted based on a thin flux tube model that predicts Alfvénic waves driven by impulsive interchange reconnection localized as narrowly as ∼1.6 Mm with a magnetic flux of ∼5.4 × 10¹⁷Mx, belonging to the smallest magnetic features in the quiet Sun. This detection of intricate corona–chromospheric coupling highlights the power of high-resolution imaging in unraveling the mechanisms behind small-scale solar ejections across atmospheric layers. 

Abstract Despite decades of research, the fundamental processes involved in the initiation and acceleration of solar eruptions remain not fully understood, making them long-standing and challenging problems in solar physics. Recent high-resolution observations by the Goode Solar Telescope have revealed small-scale magnetic flux emergence in localized regions of solar active areas prior to eruptions. Although much smaller in size than the entire active region, these emerging fluxes reached strengths of up to 2000 G. To investigate their impact, we performed data-constrained magnetohydrodynamic simulations. We find that while the small-scale emerging flux does not significantly alter the preeruption evolution, it dramatically accelerates the eruption during the main phase by enhancing the growth of torus instability, which emerges in the nonlinear stage. This enhancement occurs independently of the decay index profile. Our analysis indicates that even subtle differences in the preeruption evolution can strongly influence the subsequent dynamics, suggesting that small-scale emerging flux can play a critical role in accelerating solar eruptions. 

Abstract Solar extreme-ultraviolet (EUV) irradiance plays a crucial role in heating the Earth’s ionosphere, thermosphere, and mesosphere, affecting atmospheric dynamics over varying time scales. Although significant effort has been spent studying short-term EUV variations from solar transient events, there is little work to explore the long-term evolution of the EUV flux over multiple solar cycles. Continuous EUV flux measurements have only been available since 1995, leaving significant gaps in earlier data. In this study, we propose a Bayesian deep learning model, named SEMNet, to fill the gaps. We validate our approach by applying SEMNet to construct Solar and Heliospheric Observatory/Solar EUV Monitor EUV flux measurements in the period between 1998 and 2014 using CaIIK images from the Precision Solar Photometric Telescope. We then extend SEMNet through transfer learning to reconstruct solar EUV irradiance in the period between 1950 and 1960 using CaIIK images from the Kodaikanal Solar Observatory. Experimental results show that SEMNet provides reliable predictions along with uncertainty bounds, demonstrating the feasibility of CaIIK images as a robust proxy for long-term EUV fluxes. These findings contribute to a better understanding of solar influences on Earth’s climate over extended periods. 

Abstract On 2024 July 25, while observing the solar active region NOAA 13762 with the high-resolution 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory, we witnessed two mysterious phenomena: the partial detachment of filament strands from its main body in the chromosphere and the sudden disappearance of a sunspot penumbra in the photosphere, the former accompanied by small flares. Our analysis reveals a spatiotemporal correlation between the filament peeling process and the penumbral disappearance. To understand the above observations physically, we performed a magnetohydrodynamic simulation that successfully replicated the disappearance of the penumbra as a consequence of weakened horizontal magnetic field. The simulations demonstrate that both the filament peeling and the penumbral decay are driven by the same underlying process: the upward expansion of the magnetic flux rope induced by null point magnetic reconnection. These results suggest a novel mechanism by which the Sun sheds magnetic flux to interplanetary space in the form of filament peeling and penumbral disappearance.