Solar Physics最新文献

{"title":"Dissipative Torsional Alfvén Waves in Solar Photospheric Flux Tubes","authors":"Lucas Romero,&nbsp;Roberto Soler","doi":"10.1007/s11207-026-02720-3","DOIUrl":"10.1007/s11207-026-02720-3","url":null,"abstract":"<div><p>Photospheric bright points represent the footpoints of magnetic flux tubes, which can guide magnetohydrodynamic (MHD) waves such as torsional Alfvén waves. These waves propagate upward from the photosphere into the upper atmosphere, transporting energy and contributing to plasma heating through their dissipation. This study aims to analyze, from a theoretical perspective, the spectrum of torsional Alfvén waves in solar photospheric flux tubes. The linearized resistive MHD equations are solved in a cylindrical flux tube model whose physical properties vary in the radial direction. The eigenvalues and eigenfunctions of torsional Alfvén waves are computed using analytical and semi-analytical methods for different configurations with increasing levels of complexity. The results show that, under realistic photospheric conditions, a significant number of propagating eigenmodes exist, including internal modes and discretized modes of the Alfvén continuum. These modes are not strictly confined to the interior of the flux tube, and their eigenfunctions extend into the surrounding plasma as well. The results suggest that photospheric convective motions could naturally deposit energy into a broad spectrum of torsional modes capable of propagating upward.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148871713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiscale Periodic Variations of 10.7 cm Radio Flux During Solar Cycles 18 – 25","authors":"Yu Fei,&nbsp;Lei Zhang,&nbsp;Chun Li,&nbsp;Linhua Deng,&nbsp;Yaqi Ding","doi":"10.1007/s11207-026-02726-x","DOIUrl":"10.1007/s11207-026-02726-x","url":null,"abstract":"<div><p>The separation of multiscale fluctuations in the solar <span>(F_{10.7})</span> flux is hindered by substantial spectral overlap. We investigate the nonlinear dynamical evolution of <span>(F_{10.7})</span> across Solar Cycles 18 – 25 (1947 – 2025) using a hybrid method that combines Singular Spectrum Analysis (SSA) with log-frequency hierarchical clustering. This framework effectively mitigates the spectral mixing associated with conventional filtering and provides a more robust decomposition of the signal. The main results are as follows: (1) The <span>(F_{10.7})</span> flux is objectively decomposed into a secular trend, the 11-year Schwabe cycle, the 27-day rotational modulation, and intermediate-period components. (2) An intermittent Quasi-Biennial Oscillation (QBO) is isolated in the 1 – 3-year band, with dominant periods near 2.39 and 1.78 years, together with an additional 3.36-year component consistent with a Quasi-Triennial Oscillation (QTO). (3) QBO variability is preferentially enhanced during the ascending and maximum phases but does not scale monotonically with peak background activity; the largest excursions occur during SC22, whereas the stronger SC19 exhibits a comparatively moderate response. (4) The intermittent wave-packet morphology and marked cycle-to-cycle variability support the interpretation of the QBO as an instability-related secondary component rather than a persistent independent oscillation.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148871614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Are Fourier Power Spectra a Reliable Tool to Explore the Solar Photospheric Velocity Field?","authors":"Lotfi Yelles Chaouche,&nbsp;Amina Boulkaboul,&nbsp;Yassine Damerdji","doi":"10.1007/s11207-026-02717-y","DOIUrl":"10.1007/s11207-026-02717-y","url":null,"abstract":"<div><p>The solar photosphere exhibits a wide range of multi-scale dynamical phenomena, commonly analyzed through Fourier power spectra of velocity fields. However, the physical relevance of these spectra has been questioned, particularly regarding whether scale-dependent power arises from intrinsic dynamics or from edge-related artifacts in the data. In this study, we investigate the origin of power spectra derived from vertical velocity fields obtained in quiet-Sun three-dimensional magnetohydrodynamic (MHD) simulations. A series of controlled numerical experiments is performed. First, intergranular lanes were replaced with sharp edges with a height of <span>(-0.2~mbox{km},mbox{s}^{-1})</span>, <span>(-2~mbox{km},mbox{s}^{-1})</span> and <span>(-5~mbox{km},mbox{s}^{-1})</span>. Subsequently, noise was included with a variety of bin sizes in the intergranular lanes to produce various types of edges. Finally, the resolution was reduced and data were re-binned to a grid size up to 16 times the original one.</p><p>Our results show that the introduction of edges has a negligible effect on the overall shape and consistency of the power spectra when compared to the original unperturbed data. Noticeable distortions arise only in undersampled datasets, and these effects drastically diminish when statistically significant samples are considered. Complementary Monte Carlo simulations with synthetic data demonstrate that edges induce spurious oscillatory features in spectra of isolated two-dimensional fields, which cancel out when multiple realizations are combined, indicating that such artifacts behave as unsynchronized perturbations. These findings indicate that photospheric velocity power spectra predominantly reflect genuine physical processes rather than edge effects, except in limited cases involving small or poorly sampled datasets. Furthermore, analysis of the positive component of the vertical velocity reveals a more extended power-law range than that of the full vertical velocity, suggesting improved access to inertial-range dynamics relevant to turbulence studies.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148871575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of Coronal Extreme Ultraviolet Shockwaves Without a Coronal Mass Ejection Event","authors":"Robert Bush,&nbsp;John Stefan,&nbsp;Alexander Kosovichev","doi":"10.1007/s11207-026-02716-z","DOIUrl":"10.1007/s11207-026-02716-z","url":null,"abstract":"<div><p>A leading theory of sunquake generation involves flare-accelerated particles depositing energy into the photosphere. Simulations of sunquake excitation suggest co-excitation with wavefronts propagating in the corona, similar to large-scale coronal propagating fronts (LCPFs), and also generate Moreton-Ramsey waves in the chromosphere. To investigate observational evidence for the particle-driven mechanism in LCPFs, we compare populations of events associated with and without coronal mass ejections (CMEs). CMEs are known to generate coronal shock waves also observed in EUV emission. We employ visual inspection of flare events that generate LCPFs using Atmospheric Imaging Assembly (AIA) and Large Angle and Spectrometric Coronagraph (LASCO) coronagraph images to find that the large-scale coronal waves associated with CMEs propagate noticeably faster. Then we examine “standalone flare events” (those that generate coronal waves without CMEs), using soft X-ray (SXR) data from the GOES satellite and focusing on characteristics related to magnetic energy release rate. This reveals that such standalone or confined flares differ from sunquake flares: they are less impulsive and energetic than sunquake flares. However, they are more impulsive but less energetic than LCPF-associated flares with a CME. In particular, coronal waves accompanied by CMEs exhibit significantly higher volume emission measures, suggesting a different generation mechanism.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148838057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On Transport of Nonthermal Electrons Along Outer Spine Rope of a Circular Ribbon Flare SOL2024-03-25T06:37:00","authors":"A. T. Altyntsev,&nbsp;S. A. Anfinogentov,&nbsp;D. A. Zhdanov,&nbsp;N. S. Meshalkina,&nbsp;I. I. Myshyakov,&nbsp;E. F. Ivanov,&nbsp;Chengming Tan,&nbsp;Zhao Wu","doi":"10.1007/s11207-026-02722-1","DOIUrl":"10.1007/s11207-026-02722-1","url":null,"abstract":"<div><p>Observations with the Siberian Radioheliograph (SRH) provide measurements of the spectral and polarization characteristics of microwave emission originating from footpoints of a large-scale coronal magnetic rope. Nonthermal electrons were injected into the western footpoint of this structure from the main energy release site (kernel) of a circular ribbon flare (CRF), allowing us to study particle transport in closed magnetic configurations. Microwave sources were observed at the injection and precipitation sites, separated by a distance of 215 arcsec. The energy release mechanisms responsible for initial heating, impulsive acceleration of electrons, and plasma ejections are discussed. For the first time, the spectra of microwave emission from a remote source were measured both in intensity and circular polarization. Modeling results indicate that this emission originates from moderately relativistic electrons, reflected at the magnetic mirror in the remote footpoint. The pitch-angular anisotropy of distribution function of electrons moving along the rope and trapped inside is confirmed by generation of coherent emissions of different types appearing as fine spectral structures on the decimeter and meter dynamic spectra. Overall, the observations of the spectral and spatial structure of electromagnetic emission obtained from SRH and the SOLARSPEL spectropolarimeter open new opportunities for verifying injection and transport mechanisms of accelerated electrons in coronal magnetic structures.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solar Activity Forecasting Using a Hybrid Conv1D-LSTM Model Validated on Solar Cycle 25","authors":"Hernán D. Guerrero-Caguasango,&nbsp;Santiago Vargas-Domínguez","doi":"10.1007/s11207-026-02710-5","DOIUrl":"10.1007/s11207-026-02710-5","url":null,"abstract":"<div><p>We present a hybrid Conv1D–Long Short-Term Memory (Conv1D-LSTM) deep-learning model for monthly sunspot number (SSN) forecasting, implemented in the Julia programming language using Flux.jl. The model is trained on the complete Sunspot Index and Long-term Solar Observations (SILSO) dataset (January 1749–February 2026; 3326 months) with a physically motivated partition aligned with solar cycle boundaries: training on Cycles 1 – 23, validation on Cycle 24, and test on Cycle 25. The input window size (<span>(W = 60)</span> months) is determined objectively from the autocorrelation structure of the training series, a value that corresponds physically to approximately half the Schwabe cycle and captures the phase memory necessary for short-term solar activity prediction. Morphological similarity between Cycle 25 and historical cycles is quantified via Dynamic Time Warping (DTW), providing independent astrophysical context for the forecast. Model robustness is assessed through rolling walk-forward cross-validation over Cycles 20 – 23 (mean absolute error (MAE) = <span>(17.90 pm 2.11)</span> SSN (sunspot number) units, mean over four folds). Using a one-step-ahead evaluation protocol (in which each prediction uses the 60 preceding real observations as input, consistent with operational space weather forecasting), the model achieves MAE = 10.17 and root mean square error (RMSE) = 14.89 on Cycle 24, and MAE = 13.92 and RMSE = 19.24 on Cycle 25. A retrospective evaluation against the confirmed Cycle 25 maximum (SSN ≈ 160.9, October 2024) yields an amplitude error of 4.0%, compared with a 28.5% underestimate by the NOAA/NASA consensus panel. We note that this comparison is made with the observational advantage of hindsight: the confirmed maximum falls within our test set, whereas prior studies necessarily operated under prospective uncertainty. While the 4.0% error reflects excellent monthly tracking fidelity, this is distinct from the more challenging task of predicting cycle amplitude 5+ years in advance: the one-step-ahead protocol relies on the 60 preceding real observations as input and should not be interpreted as evidence of prospective long-range forecasting skill. The complete, reproducible Julia source code is publicly available at https://github.com/hernandguerreroc/solar-forecast-julia.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-026-02710-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Solar Cycle Variation of the Distribution of Photospheric Magnetic Flux Features","authors":"Callan N. Noble,&nbsp;Clare E. Parnell,&nbsp;Thomas Neukirch","doi":"10.1007/s11207-026-02715-0","DOIUrl":"10.1007/s11207-026-02715-0","url":null,"abstract":"<div><p>We use statistical tools to analyse data from the Solar Dynamics Observatory Helioseismic and Magnetic Imager to determine the distribution of the magnetic flux of photospheric magnetic features and its variation over a full solar cycle. In particular, we use statistical figures of merit to test how well different types of probability density function represent the magnetic flux distribution inferred from the data and how their shape changes over the solar cycle. Our analysis shows that a double power law provides the best representation of the data over the full solar cycle and we present the dependence of the power law exponents on the phase of the solar cycle. The nature of the observed flux distributions at different times during the solar cycle is significant because it could be used to try and infer information about solar magnetic field generation mechanisms. We discuss potential implications of a double power law distribution for solar magnetic field generation.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-026-02715-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multipoint Observations of Polar Crown Filament Eruption Using Solar Orbiter and Solar Dynamics Observatory","authors":"Johan Muhamad,&nbsp;Rasdewita Kesumaningrum,&nbsp;Muhamad Zamzam Nurzaman,&nbsp;Tiar Dani,&nbsp;Santi Sulistiani,&nbsp;Nanang Widodo,&nbsp;Farahhati Mumtahana,&nbsp;Farahana Kamarudin,&nbsp;Karzaman Ahmad,&nbsp;Mohammad Redzuan Tahar","doi":"10.1007/s11207-026-02721-2","DOIUrl":"10.1007/s11207-026-02721-2","url":null,"abstract":"<div><p>On 20 April 2023, a prominence eruption was observed near the north pole of the Sun. This feature, visible as a large Polar Crown Filament (PCF) for several days prior to the event, was captured by Solar Orbiter from a vantage point distinct from that of the Solar Dynamics Observatory (SDO). By combining stereoscopic observations from SDO and Solar Orbiter, we identified the 3D structure of the filament and analyzed the dynamics of the eruption. We found that small, mixed-polarity magnetic regions existed within the dominant polarity region at the north pole prior to the eruption. The presence of a Magnetic Flux Rope (MFR) was suggested by the signature of an oval-like cavity surrounding the prominence, as observed in both coronal imagery and during a coincident Total Solar Eclipse (TSE). Our analysis indicates that successive magnetic reconnections led to the release of the MFR into interplanetary space. The precise locations of the footpoints associated with the reconnecting magnetic-field lines and the MFR were determined using a triangulation method based on brightening locations during the eruption. Furthermore, the occurrence of a jet-like structure suggests that reconnection between closed and open field lines may have also occurred. Through analysis of the 3D geometric evolution of the PCF, we propose that a magnetic breakout process drove the eruption.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic Reconnection Process in Partially Ionized Fluids: Insights from the Solar Chromosphere","authors":"Adrian R. Montañez-Lobo,&nbsp;Fabio D. Lora-Clavijo","doi":"10.1007/s11207-026-02714-1","DOIUrl":"10.1007/s11207-026-02714-1","url":null,"abstract":"<div><p>Magnetic reconnection converts stored magnetic energy into kinetic energy, heat, and radiation. While extensively studied in fully ionized plasmas, observations show that ionization and recombination also play a role by modifying the local plasma resistivity and enabling additional heating channels. This study examines magnetic reconnection in the partially ionized solar chromosphere, analyzing its morphology and energy releases with attention to elastic collisions, ionization, and recombination. The MAGNUS code, originally built for ohmic resistivity and heat transfer, was modified to handle elastic and inelastic collisions. The simulations are 2.5D resistive MHD with two-fluid effects (charged + neutrals), adapted to handle interactions via these collision terms. A mixed explicit-implicit scheme was implemented to manage the stiffness of these terms. Simulations were carried out for three different magnetic field strengths: <span>(100,text{G})</span>, <span>(110,text{G})</span>, and <span>(120,text{G})</span>. These values correspond to the low to mid chromosphere in quiet Sun conditions. We found that reconnection heats the plasma components by <span>(18%)</span> to <span>(110%)</span>. Although plasma beta rises only slightly, the energy release grows far more, indicating that charged–neutral collisions, not just beta or available magnetic energy, drive the enhanced reconnection. Furthermore, ionization and recombination become most significant in regions of peak temperature, particularly where particles are accelerated. Maximum reconnection rates from temporal analysis are 0.226, 0.253, and 0.279, respectively. Finally, in terms of energy, our results show that in a chromospheric volume of <span>(0.4 times 0.01 times 0.4,text{Mm}^{3})</span>, the energy released ranges from <span>(10^{22})</span> to <span>(10^{23},text{erg})</span>.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11207-026-02714-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metric Type II Radio Emission Associated with Coronal Mass Ejections of Large Angular Widths: Some New Insights","authors":"Mayank Rajput,&nbsp;Susanta Kumar Bisoi,&nbsp; Janardhan Padmanabhan","doi":"10.1007/s11207-026-02711-4","DOIUrl":"10.1007/s11207-026-02711-4","url":null,"abstract":"<div><p>Solar Type II radio bursts are manifestations of shocks produced by explosive and eruptive solar activities, such as solar flares and coronal mass ejections (CMEs). Metric range or coronal Type II bursts are interesting because of their association with CME-driven shocks. It is therefore important to examine the correlation between the properties of Type II bursts and the associated CMEs. This, in turn, would be useful in understanding the impact of CMEs on space weather and geomagnetic activity. We conducted a statistical study of 23 coronal Type II radio bursts in the frequency range 150 – 20 MHz, for the period spanning 2007 – 2024. We correlated the frequency bandwidth of coronal Type II bursts with the angular width of the associated CMEs. Our investigation showed an anti-correlation between the two quantities with a correlation coefficient of ≈ −0.62. We further deduced the height of the Type II bursts (r_{<i>TypeII</i>}) at the onset time of the burst and compared them with the estimated height of the associated CMEs/shocks (r_<i>CME</i>). With the exception of one event, for the rest of the Type II burst events, r_{<i>TypeII</i>} was &lt; r_<i>CME</i>. The results suggest that the CMEs with large angular widths produce narrow-band Type II emissions, and these Type II emissions could possibly be produced in the flank region of the CME-driven shock rather than at the shock front.</p></div>","PeriodicalId":777,"journal":{"name":"Solar Physics","volume":"301 8","pages":""},"PeriodicalIF":2.4,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148782481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}