The research, led by Oleg Stepanyuk of the Institute of Astronomy and National Astronomical Observatory at the Bulgarian Academy of Sciences, together with Werner Pötzi of the Kanzelhöhe Observatory for Solar and Environmental Research at the University of Graz, Momchil Dechev, Rositsa Miteva, and Kamen Kozarev, extends a hybrid algorithmic and data-driven approach the team had previously applied to data from the Atmospheric Imaging Assembly aboard NASA’s Solar Dynamics Observatory. In that earlier work, the method was used to segment extreme ultraviolet waves and shock fronts associated with solar eruptions. The new effort shifts the focus to hydrogen-alpha observations from Kanzelhöhe Observatory, an Austrian facility that has monitored the Sun with high temporal resolution for decades and whose data are now integrated into the European Space Agency’s Space Weather Service Network.

Why does ground-based hydrogen-alpha imaging matter for this task? Space telescopes offer uninterrupted coverage, but ground-based instruments provide a long historical archive and frequent sampling during daylight hours, capturing the slow morphological evolution of filaments that often precedes an eruption. Researchers have long noted that changes in a filament’s shape, height, and internal motion can signal that the magnetic flux rope anchoring it is approaching a critical state. Theoretical work on mechanisms such as the torus instability and kink instability, together with statistical studies linking prominence destabilization to coronal mass ejections, has established that filaments are not merely passengers on erupting structures but often visible tracers of the eruption process itself. Systematic, automated monitoring of these tracers across many years of data is therefore a natural foundation for forecasting.

The technical core of the new study is image segmentation: teaching a neural network to label, pixel by pixel, which parts of a full-disk solar image belong to a filament. The team employed compact U-Net-based architectures, a family of convolutional neural networks originally developed for biomedical image segmentation that have become a workhorse in solar physics as well. U-Net’s encoder-decoder design, with skip connections that carry fine spatial detail from the encoding path to the decoding path, is well suited to the elongated, low-contrast, and highly variable shapes of solar filaments. The models were pre-trained on synoptic and normalized image data, and the researchers systematically examined how performance depends on training-set engineering, preprocessing choices, and the selection of loss metrics used to guide optimization.

One of the study’s most distinctive contributions is a leakage-aware, sparse multi-year sampling strategy. In machine learning applied to images, data leakage occurs when samples that are too similar to one another end up split between training and test sets, inflating apparent performance. Solar images are especially vulnerable to this problem because filaments persist for days and evolve slowly: consecutive frames are nearly identical, and even images taken days apart can share large structures. By carefully spacing the sampled images across multiple years and accounting for temporal correlation, the team ensured that their reported accuracy reflects genuine generalization to unseen solar conditions rather than memorization of long-lived features. This kind of methodological rigor, borrowed in part from lessons learned in other imaging domains such as digital pathology, is essential if segmentation models are to be trusted in operational settings.

Perhaps the most conceptually interesting result concerns normalization, the practice of rescaling input data or internal network activations to stabilize training. Deep networks commonly rely on techniques such as batch normalization or weight normalization, and practitioners routinely apply per-image normalization schemes such as z-score or min-max rescaling to raw inputs. The authors performed a combined analytical and numerical study of how externally imposed, fixed normalization compares with letting the network work from native input values in compact U-Net models for hydrogen-alpha filament segmentation. Their conclusion is striking: synoptic photometric calibration already supplies a physics-aware normalization, internal normalization layers supply learned, per-channel scaling, and an additional external per-image normalization inserted between the two is at best redundant and at worst actively destructive for sparse, photometrically defined classes like hydrogen-alpha filaments.

The practical guidance that follows from this analysis is concrete. The authors recommend keeping synoptic photometric calibration intact rather than stripping it away with per-image rescaling, applying at most a fixed, dataset-global linear rescale to bring inputs into a range suitable for optimizer stability, and placing normalization blocks immediately after each skip-connection concatenation in the decoder so that encoder and bottleneck streams are equalized before subsequent convolutions. For training across multiple instruments, such as combining data from ChroTel, the Global Oscillation Network Group, and Kanzelhöhe, they suggest histogram matching to a canonical reference frame rather than per-image equalization, preserving relative photometry while removing instrument-to-instrument drift. They also recommend leaving the final one-by-one convolution un-normalized and using Dice or Tversky losses, which handle the severe class imbalance that arises when thin filaments occupy only a small fraction of each image.

This attention to compact, efficient models reflects a broader trend in solar research. Lightweight segmentation networks are increasingly being deployed on edge computing devices and field-programmable gate arrays, enabling real-time analysis at observatories without recourse to large data centers. Related efforts in the literature include ultralightweight U-Net variants designed specifically for full-disk hydrogen-alpha filament segmentation, semi-supervised deep learning methods for universal filament detection, and object-detection frameworks adapted for solar features. The Kanzelhöhe-based work contributes to this ecosystem not only with its models, which the team publishes and regularly updates in a public repository, but with hard-won engineering knowledge about what actually matters when training data are sparse, photometric conventions are meaningful, and the target class is geometrically delicate.

The scientific payoff of reliable automated filament segmentation extends well beyond cataloging. Once filaments can be consistently detected and tracked across years of observations, their morphological evolution can be correlated with eruption onset, providing quantitative precursors for forecasting models. Filament material itself has been directly observed within interplanetary coronal mass ejections, confirming the physical chain from quiescent structure to Earth-directed disturbance. Statistical studies of critical heights for prominence destabilization and of the relationship between erupting filaments and coronal mass ejection kinematics all depend on accurate, consistent measurements of filament position, area, and shape over time, measurements that manual cataloging cannot deliver at the scale of modern archives.

Funded by the Bulgarian National Science Foundation and Austria’s Agency for Education and Internationalisation, the work exemplifies how international collaboration between observatories and research institutes can convert routine monitoring data into forecasting capability. As solar activity cycles through its maxima and the volume of ground-based imagery continues to grow, tools like the ones described in this study will become indispensable sentinels, quietly scanning the Sun’s dark ribbons for the first signs that a storm is brewing. For a civilization increasingly dependent on satellites, aviation routes over the poles, and interconnected power infrastructure, teaching machines to read the Sun’s warnings may prove one of the most quietly consequential applications of artificial intelligence in the solar sciences.

Subject of Research: Deep learning segmentation of solar filaments from ground-based hydrogen-alpha observations for space weather forecasting

Article Title: Data-Driven Segmentation of Solar Filaments Based on Ground-Based Instrument Data

Article References: Data-Driven Segmentation of Solar Filaments Based on Ground-Based Instrument Data. (n.d.). https://doi.org/10.1007/s11207-026-02741-y

Image Credits: AI Generated

DOI: 10.1007/s11207-026-02741-y

Keywords: solar filaments, solar prominences, coronal mass ejections, space weather, deep learning, U-Net, image segmentation, normalization, Kanzelhöhe Observatory, hydrogen-alpha, Solar Physics, machine learning

Type II radio bursts are slow-drifting emissions in dynamic radio spectra, first identified in the late 1940s, that arise from plasma oscillations excited by electrons accelerated at shock waves. When a shock disturbs the coronal plasma, electrons are accelerated and stream along magnetic field lines, exciting electrostatic oscillations at the local plasma frequency, which then convert into escaping electromagnetic radiation. Because the plasma frequency is proportional to the square root of the local electron density, the emission drifts from higher to lower frequencies as the shock travels outward through the corona’s tenuous, rapidly thinning atmosphere. Bursts observed in the metric range, roughly from tens to hundreds of megahertz, trace the low corona, where the plasma is densest and the shocks are young. It is precisely this region that matters most for space weather, because the early evolution of a CME and its shock determines whether the disturbance will evolve into a geoeffective interplanetary structure capable of compressing Earth’s magnetosphere days later.

The team assembled a sample of 23 coronal Type II bursts observed between 2007 and 2024 in the frequency range from about 150 MHz down to 20 MHz. The radio data were drawn from three complementary instruments: the Gauribidanur Low-Frequency Solar Spectrograph in India, the Culgoora radiospectrograph in Australia, and stations of the e-CALLISTO worldwide network of solar radio spectrometers. Each burst was matched to a CME observed in white light by the Large Angle and Spectroscopic Coronagraph aboard the Solar and Heliospheric Observatory, with supporting imagery from the Sun Earth Connection Coronal and Heliospheric Investigation package on the twin STEREO spacecraft and the Atmospheric Imaging Assembly on the Solar Dynamics Observatory. By cross-referencing the onset times of the radio emission with the projected positions and kinematics of the erupting structures, the authors were able to associate each burst with a specific CME and characterize both the radio signature and the erupting plasma.

The central result of the study is a clear anti-correlation between the frequency bandwidth of the Type II bursts and the angular width of the associated CMEs, quantified by a correlation coefficient of approximately minus 0.62. In practical terms, CMEs that span a large range of position angles in the coronagraph images tend to produce radio bursts whose emission is confined to a narrow band of frequencies, while narrower CMEs are associated with bursts spread across a wider frequency span. The inverse relationship is striking because angular width is often treated as a rough proxy for the lateral extent and energetic clout of an eruption. One might naively expect a broader shock front to sweep through a wider range of coronal conditions and therefore generate emission across a broader spectral window. The data say the opposite.

The authors interpret this counterintuitive result through the geometry of the shock and the density structure of the ambient corona. A Type II burst’s instantaneous bandwidth reflects the range of electron densities at which the shock is simultaneously exciting plasma emission. If a shock propagates through a relatively homogeneous medium, or if the emission is generated primarily in a localized region rather than along the entire shock front, the instantaneous bandwidth will be narrow. The anti-correlation with angular width suggests that wide CMEs, whose flanks spread out laterally over large position angles, tend to produce emission from restricted parts of the shock surface where the conditions for electron acceleration are most favorable. The study therefore points toward the flank regions of CME-driven shocks, rather than the nose or leading edge, as the likely sources of these metric Type II emissions.

This interpretation is reinforced by a second line of evidence in the paper: a careful comparison of heights. For each event, the team deduced the height of the Type II burst source at the onset time of the burst, derived from the emission frequency through coronal electron density models, and compared it with the estimated height of the associated CME or shock at the same moment, obtained by interpolating the CME’s measured position in coronagraph images. With the exception of a single event in the entire sample of 23, the height inferred from the radio emission was smaller than the height of the CME leading edge. In other words, the radio source consistently sat below the front of the erupting structure, a configuration that is difficult to reconcile with emission generated at the shock nose itself but entirely consistent with emission arising on the flanks of a laterally expanding shock, which lag behind the leading edge in height.

The lone exception in the sample is itself informative, because events in which the radio source coincides with or exceeds the CME height are the cases in which a nose or leading-edge origin is most plausible. The rarity of such cases in this sample of wide CMEs underscores the statistical conclusion. Previous imaging studies, including observations with the Low Frequency Array and the Murchison Widefield Array, have already shown that individual Type II bursts can have multiple, spatially separated sources and that different sections of a shock can accelerate electrons at different times. The present work adds a statistical dimension to that picture, suggesting that for broad, laterally extensive eruptions the flank geometry systematically dominates the radio output.

The technical foundation for the height estimates rests on well-established coronal density models that link emission frequency to plasma density, calibrated against eclipse and radio heliograph measurements, including multiplicative factors to account for density enhancements in streamers and active regions. The choice of density model introduces some uncertainty, but the systematic nature of the height comparison across 23 events, all analyzed consistently, gives the result robustness that a single event study cannot match. The frequency bandwidth measurements, meanwhile, were made directly from the dynamic spectra, capturing the span of frequencies over which the burst emission was present at a given stage of its evolution.

The implications extend beyond solar physics into the practical business of space-weather prediction. Interplanetary shocks driven by CMEs compress Earth’s magnetosphere on arrival, and the severity of the resulting geomagnetic disturbance depends on the shock’s speed, structure and history. Because Type II bursts are direct radio signatures of shock acceleration, they can in principle serve as early indicators of a shock’s strength and trajectory, and several research groups have explored using metric Type II observations to forecast shock arrival times at Earth. A relationship between burst bandwidth and CME angular width adds a potentially useful piece to that forecasting toolkit: a narrow-band metric burst following a wide CME would hint that the radio-emitting part of the shock is developing on its flanks, which may carry implications for where energetic particle acceleration is strongest and how the disturbance will couple to the heliospheric magnetic field.

The study also feeds into a long-running scientific debate about the origin of metric Type II bursts, which dates back more than half a century. Early proposals attributed the bursts to blast waves generated by solar flares, while decades of subsequent work have increasingly linked them to CME-driven shocks, with timing ambiguities persisting in individual events. Statistical studies like this one, which correlate a spectral property of the burst with a morphological property of the CME, sidestep some of the timing controversies and instead probe the physical relationship between the two phenomena. The result that wide CMEs produce narrow-band emission, plausibly from their flanks, offers a new observational constraint that any complete model of coronal shock emission must reproduce.

There remain open questions. The sample of 23 events, while respectable for a study of rare radio phenomena, is modest, and extending the analysis to a larger population of bursts, including those at decametric and interplanetary wavelengths, would test whether the anti-correlation persists farther from the Sun. Imaging spectroscopy with modern instruments capable of directly locating Type II sources, rather than inferring their heights from frequency, would provide the definitive test of the flank-origin hypothesis. The authors’ dataset, drawn from publicly available catalogs and spectrograph archives, is well suited for such follow-up, and the combination of ground-based radio spectroscopy with space-based white-light coronagraphy remains the workhorse technique for this field.

For now, the study delivers a clear and quotable takeaway: the width of a solar eruption and the width of its radio scream are inversely related, and the radio source usually hides below the CME’s leading edge rather than riding at its crest. As the current solar cycle continues to deliver energetic eruptions, each new wide CME accompanied by a narrow-band Type II burst will be another data point in a picture that is steadily coming into focus, one plasma-frequency drift at a time.

Solar energetic particle events, or SEPs, are sudden surges in the population of electrons, protons, and heavy ions speeding through interplanetary space. They are widely understood to arise from particles accelerated by magnetic reconnection in solar flares and at shock waves that form ahead of fast CMEs. The most intense events can deliver radiation doses lethal to unshielded astronauts and can damage spacecraft electronics, which is why predicting them has become a priority as agencies prepare for sustained human missions to the Moon and Mars. For decades, forecasters have relied on space-based coronagraphs such as the Large Angle and Spectrometric Coronagraph on the Solar and Heliospheric Observatory, which images the corona only above roughly 2.3 solar radii from the Sun’s center. That limitation matters because the fastest SEP particles can reach Earth in a matter of tens of minutes, arriving before the parent CME has even entered the field of view of such instruments. By the time a space-based coronagraph confirms a fast eruption, the radiation event may already be underway.

The K-Coronagraph, installed at the 3,440-meter altitude Mauna Loa observatory in late 2013, was designed to close precisely this gap. As an internally occulted, ground-based instrument, it images the polarization brightness of the corona, produced by Thomson scattering of photospheric light off free electrons, in a near-infrared passband spanning 720 to 750 nanometers, and it does so starting at just 1.05 solar radii and extending to 3.0. Its 15-second cadence represented a dramatic improvement over the 3-minute cadence of its predecessors, the Mark-3 and Mark-4 coronameters, and a fully automated processing pipeline reduced data latency to 2.5 minutes, compared with as much as 24 hours previously. The pipeline includes an automatic CME detection algorithm that scans processed images and dispatches email alerts containing the eruption’s detection time, height, position angle, and speed, along with a “heartbeat” signal that tells forecasters the observatory is watching and sees nothing alarming.

To identify which of the roughly 600 CMEs detected by K-Cor since 2013 were accompanied by SEPs, the team drew on an updated catalog of events including protons of approximately 25 MeV observed by the High Energy Telescopes aboard the twin STEREO spacecraft and by instruments on near-Earth satellites such as SOHO’s Electron Proton Helium Instrument and Energetic and Relativistic Nuclei and Electron experiment. The combination proved powerful because of orbital geometry: at the start of K-Cor operations near the maximum of Solar Cycle 24, STEREO-B sat on the far side of the Sun, magnetically well connected to the Sun’s eastern limb, a region from which energetic particles are difficult to detect from Earth. After contact with STEREO-B was lost in October 2014, STEREO-A drifted into a similarly advantageous position. Of 215 individual SEP events catalogued during the study window, most occurred during the observatory’s daily data gaps, and in five cases K-Cor was observing but saw no CME, generally because the eruption was far from the plane of the sky where the instrument’s sensitivity falls off, or because elevated instrumental stray light degraded early observations. That left 27 confirmed SEP-associated CMEs.

The comparison with the control sample, drawn from a 2023 catalog of near-limb K-Cor events compiled by Song and colleagues, produced differences that were striking in their consistency. The average and median angular widths of the SEP-producing CME drivers were a factor of two larger than those of the non-SEP events, both in the inner corona and in the middle corona where space-based instruments took over. The average speed of SEP CMEs in the inner corona was more than twice that of their quiet counterparts, and nearly twice as fast in the middle corona. More than 80 percent of all the CMEs in both samples were accelerating as they climbed through the inner corona, but the average acceleration for the SEP events was almost a factor of three larger. Mass estimates from the Coordinated Data Analysis Workshops catalog, derived from LASCO brightness measurements, told the same story: the average SEP CME was nearly three times more massive than the average non-SEP event, with median masses of 8.7 times ten to the fifteenth grams versus 2.1 times ten to the fifteenth.

The study also found a possible new telltale signature in extreme-ultraviolet images from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly. Among 64 events whose low-coronal morphology could be classified, nine displayed what the authors call very hot flux ropes, structures visible only in the hottest coronal channels and often trailing the cooler erupting bubble by roughly 0.1 solar radii. Seven of those nine, or 78 percent, were associated with SEP events, making the hot flux rope one of the strongest indicators of an impending radiation storm, though the authors caution it is not a necessary one, since eight of the fifteen classified SEP CMEs lacked the feature. The team further tied CME kinematics to flare timing, showing directly that over 70 percent of CMEs in both samples stood below five solar radii at the moment of peak soft X-ray flux, a relationship previously established only through extrapolation, and one that SEP prediction models may be able to exploit.

Perhaps the most operationally significant number in the study is 28 minutes. That is the average interval between K-Cor’s first detection of an SEP-associated CME and LASCO C2’s first detection of the same event, a head start delivered before any accounting of the hours of telemetry latency that can delay space-based imagery. K-Cor’s 84 percent detection rate of SEP CMEs occurring during its observing windows, 27 of a possible 32, was commensurate with the 92 percent rate achieved by the earlier Mk3 and Mk4 instruments over three decades. Only one of the 27 associated SEP events registered at the S1 level on NOAA’s solar radiation storm scale in the near-Earth environment, and three more would have exceeded that threshold as measured by STEREO-A far from Earth, but the authors note that the K-Cor era coincided with unusually weak solar activity, with only ten CMEs exceeding 1,800 kilometers per second compared with 37 in an equivalent span during the Mark-4 era. The Sun has produced 80 percent more fast CMEs in the less than three years since the 2022 hiatus than during the nine years of K-Cor observations themselves.

The timing of this work could hardly be more pointed. SOHO, launched three decades ago, will eventually be decommissioned, and its CME monitoring role is passing to NOAA’s new Compact Coronagraphs. CCOR-1, launched in June 2024 aboard GOES-19, and CCOR-2, launched in September 2025 on the Space Weather Follow-On mission now stationed at the Lagrange 1 point, both begin their fields of view at 3.5 solar radii or beyond, image every 15 minutes, and require a second image before a speed can be computed. The authors’ arithmetic is sobering: for a CME traveling at the study’s average SEP-associated speed of just over 800 kilometers per second, a 25 MeV proton following the nominal Parker spiral path reaches 1 astronomical unit in about 43 minutes, meaning the radiation event would already be underway by the time a CCOR speed estimate became available. Higher-energy particles, the ones that matter most for aviation and human spaceflight, arrive even sooner.

With Mauna Loa’s access road repaired, routine K-Cor observations resumed on March 31, 2026, and the instrument once again feeds near-real-time alerts to NASA’s Community Coordinated Modeling Center SEP Scoreboard. The study’s authors are careful to acknowledge the limitations of a single ground-based observatory, hemmed in by weather, daylight, staffing, and geography, and their sample excludes the rare, most extreme events simply because none occurred during an observing window. Yet their conclusion is unambiguous: ground-based coronagraphy, with its low observational threshold, rapid cadence, and 2.5-minute data latency, offers a warning capability that no current or planned space-based instrument can match on its own, and the distinctive properties of SEP-producing eruptions in the inner corona, their greater width, speed, acceleration, and mass, provide forecasters with physical signatures to watch for. As humanity prepares to send crews beyond Earth’s protective magnetosphere, the view from a mountaintop in Hawaii may prove to be one of the best early-warning systems available.

Solar activity traditionally exhibits an approximately 11-year cycle characterized by periods of heightened and diminished magnetic phenomena, including solar flares, sunspots, and coronal mass ejections. These activities significantly influence space weather, which in turn can disrupt satellite operations, communications networks, GPS accuracy, and even power grid stability on Earth. A critical challenge in solar science has been unraveling the internal processes that drive this cyclic behavior, as conventional observations focus primarily on the Sun’s outer surface.

To peer beneath this luminous veil, scientists use helioseismology—a technique akin to terrestrial seismology but applied on a solar scale. This method involves studying the propagation and frequencies of sound waves generated within the Sun’s interior. These pressure-driven modes (p-modes) reverberate through the solar interior and surface, and their frequency variations provide indirect but powerful probes into the Sun’s internal magnetic and structural state. The Birmingham Solar Oscillations Network (BiSON), a global consortium operating an array of telescopes, has been collecting such data continuously since 1981, enabling unprecedented temporal coverage of solar internal oscillations.

By tracking shifts in the frequencies of solar oscillations across solar cycles 22 through 25, from 1987 to the projected endpoint of 2025, researchers have detected a distinct pattern that diverges from what traditional surface-based solar activity indicators reveal. Notably, the relationship between these oscillations and solar surface activity measures has evolved significantly since the 23rd solar cycle. This revelation indicates a systemic long-term evolution in the solar interior’s magnetic structuring beyond the scope of surface manifestations alone.

One remarkable finding points to a progressive confinement of magnetic activity into increasingly superficial layers, within roughly 1,000 kilometers beneath the Sun’s visible surface. This restriction challenges previous conceptions that magnetic regeneration and field restructuring happen more diffusely throughout the solar convection zone. Instead, it suggests that the dynamics associated with solar magnetic activity cycles have become compressed both spatially and perhaps temporally, potentially altering the mechanisms that feed solar dynamo processes.

Another critical aspect of the study involved dissecting the solar oscillations into frequency bands—low, mid, and high—to examine the layering of internal changes at varying depths. This nuanced analysis revealed that high-frequency oscillations, which probe shallower solar layers, exhibit patterns corresponding to a stronger apparent solar cycle 25 than traditional indices would suggest. This dichotomy implies that while conventional measures observe a weakening solar surface activity, subsurface magnetic fields retain or potentially intensify their strength in these upper layers.

The implication of these findings is far-reaching. They indicate that the solar magnetic activity cycle is undergoing a structural reorganization that cannot be accounted for merely by a decrease in magnetic field intensity. Instead, such shifts denote an intrinsic alteration in how and where magnetic fields are stored and modulated inside the Sun. This evolving magnetic confinement and behavior might result in new patterns of solar activity with implications for predicting solar storms and geomagnetic disturbances that affect Earth’s environment and technological infrastructure.

Professor Bill Chaplin of the University of Birmingham, the lead author of the study, emphasized that this is the first concrete observation of a systematic change in solar behavior based on internal data. He highlighted that previous tools restricted to surface observations masked these deep-seated changes. Without the extensive longitudinal BiSON dataset and the diverse telescope network, such longitudinal insights would be unattainable, underscoring the importance of sustained global solar monitoring.

Adding to the conversation, Professor Sarbani Basu from Yale University reflected on how the newly uncovered trends point towards a fundamental reorganization in the solar magnetic field production and storage mechanisms beneath the surface. This conceptual shift challenges existing solar dynamo models that have predominantly accounted for periodicity and intensity variations based on relatively stable internal conditions across cycles.

Looking forward, the continuation of BiSON’s data acquisition throughout the remainder of solar cycle 25 and into cycle 26 will be critical to determine whether the observed changes represent a temporary anomaly or signify a deeper, sustained transition in solar magnetic behavior. Such continued monitoring is essential not only to refine dynamo theory and solar physics but to enhance the forecasting capacity of space weather events that have tangible impacts on global technological systems.

This discovery arrives at an intriguing time as the Sun’s influence on Earth is increasingly relevant given our society’s reliance on sensitive technological infrastructures vulnerable to solar storms. The scientific community, equipped now with 40 years of helioseismic observations and sophisticated analytical frameworks, stands at the cusp of unraveling the complexities of solar interior dynamics that underpin these once enigmatic magnetic cycles.

In conclusion, this study heralds a new era of insight into the Sun’s active lifeblood, where helioseismology reveals that beneath the fiery surface lies a changing internal rhythm. The findings profoundly reshape our understanding of solar magnetic activity, emphasizing that space weather is a product not just of surface phenomena but of deep seismic and magnetic processes evolving within the Sun’s interior—a cosmic twist that might rewrite future predictions of solar activity impacts on our planet.

Subject of Research: Solar internal structure and helioseismic analysis of magnetic activity cycles

Article Title: ‘Subsurface structural changes associated with successive 11-yr solar activity cycles have been progressively more confined near the surface: new helioseismic results on Cycles 22–25 from BiSON’

News Publication Date: 28-May-2026

Web References:

• Monthly Notices of the Royal Astronomical Society article
• DOI: 10.1093/mnras/stag847

Image Credits: NASA/SDO; W. J. Chaplin

Keywords

Sun, Helioseismology, Solar Cycle, Solar Magnetic Activity, Solar Interior, BiSON, Solar Oscillations, Space Weather, Solar Dynamo, Solar Physics, Solar Cycle 25, Solar Structure

The central mission of the 3UCubed satellite aligns with NASA’s Interstellar Mapping and Acceleration Probe (IMAP) initiative, designed to provide invaluable insights into the solar wind. This high-speed stream of charged particles emanating from the sun can have profound effects on the Earth’s magnetosphere and atmosphere. By studying the behavior of solar wind, scientists aspire to enhance space weather forecasting, ultimately protecting critical technologies, such as communication networks, power grids, and GPS systems, from the potentially catastrophic impacts of solar flares.

The project’s significance transcends mere technological advancement; it serves as an educational platform for students. As Noé Lugaz, a respected research professor in physics and astronomy at UNH, emphasized, this endeavor presents an extraordinary opportunity for undergraduates to engage in hands-on technical training while collaborating with their peers from different backgrounds. The experience provides not just knowledge, but also fosters a sense of community and teamwork, valuable assets as students transition into careers in fields related to aerospace, engineering, and science.

The creation of 3UCubed was the result of a concerted effort involving a team of 70 undergraduate students. These ambitious young scientists and engineers took on multifaceted roles within the project, demonstrating a range of skills from software development to hardware assembly. Notably, the name “3UCubed” not only encapsulates the mission’s objective of uplifting undergraduate students in the realms of space research but also symbolizes the tripartite collaboration among the three universities. This kind of teamwork is inherent to the spirit of research and innovation, providing a nurturing ground for the next generation of scientists.

Constructed with remarkable precision, the CubeSat will operate in the thermosphere, the high-altitude region of the Earth’s atmosphere, where it will gather vital data concerning atmospheric density and the influx of electrons stemming from space. The information collected will be particularly crucial in elucidating the processes that occur within the auroral and cusp regions, areas where solar particles interact with the Earth’s magnetic field. Such investigations are parenthetically important in our ongoing efforts to comprehend how solar activities influence our planet’s protective mechanisms.

CubeSats, characterized by their compact design and cost efficiency, have emerged as a game-changing technology in the realm of space exploration. Their standardized size, equivalent to that of a loaf of bread, allows for simplified construction and operation compared to traditional, larger satellites. This size and efficiency render CubeSats an ideal platform for students to apply theoretical knowledge in practical scenarios, facilitating a smooth transition from academic settings to professional endeavors.

Over the course of five years, the 3UCubed team dedicated themselves to the satellite’s development, engaging in a broad spectrum of activities that spanned multiple disciplines. This process included everything from writing the software code essential for the CubeSat’s operation to the intricate task of soldering wires during the construction phase. Their journey not only involved technical challenges but also required strategic planning, such as performing trade studies and orbit analyses. Several students took the initiative to select vendors for various components and overseen departmental budgets that encompassed critical aspects of power, mass, and telemetry requirements.

As Alex Chesley, a UNH mechanical engineering alumnus and former team member, reminisced about the project, he highlighted the significance of working alongside industry professionals. His enthusiasm for the aerospace sector was channeled into practical experience that he regarded as indispensable. Engaging with complex subjects in space science and instrumentation expanded his horizons and prepared him for a successful career as a configuration engineer at STS Aerospace.

The satellite’s assembly and the development of its payload instruments took place at UNH, showcasing the university’s commitment to research and innovation in aerospace. Students at SSU played a crucial role in creating the software for the ground station, which is responsible for monitoring and communicating with the satellite post-launch. Moreover, the collaborative efforts extend to Howard University, which contributed to establishing a backup ground station, guaranteeing the mission’s resilience and data integrity.

Haley Joerger, another participant from SSU, reflected on her transformative experience in the CubeSat project, detailing how mentorship was pivotal in cultivating her confidence and skill set. The experience not only prepared her for her current role as an application engineer at Keysight Technologies but also fostered enduring friendships with her teammates, illustrating the profound impact of educational collaborations on personal and professional growth.

Beyond the bounds of technical skills, the project reached out to local communities, engaging amateur radio operators and Scout groups in constructing a ground station for communication with the satellite. This initiative underscores the broader implications of space research and the importance of inspiring young minds through science and technology, as the satellite serves as a beacon of innovation and education.

As the launch date draws near, anticipation builds not only among the students and faculty involved in the project but also within the broader academic and scientific community. The data gathered from the 3UCubed satellite is expected to play a vital role in enriching our understanding of complex atmospheric phenomena and enhancing our preparedness for solar events.

In conclusion, the 3UCubed CubeSat initiative stands as a testament to the power of collaboration, the insatiable curiosity of young minds, and the wealth of knowledge that arises when educational institutions unite for a common goal. As this groundbreaking satellite prepares to embark on its journey into the cosmos, it embodies the aspirations of numerous students and researchers, paving the way for future explorations and discoveries that could redefine our understanding of the universe and our place within it.

Subject of Research: Solar Wind and Space Weather Forecasting
Article Title: Students Launch CubeSat to Enhance Understanding of Solar Wind
News Publication Date: November 6, 2025
Web References: https://www.unh.edu
References: Not specified
Image Credits: UNH, NASA 3UCubed

Keywords

CubeSat, 3UCubed, solar wind, space weather, satellite, University of New Hampshire, Sonoma State University, Howard University, NASA, space exploration, undergraduate research, technology development.

The coronal loops observed during this event displayed an average width of 48.2 kilometers, with some measuring as thin as 21 kilometers. This remarkable imaging capability might signify a breakthrough in defining the fundamental scale of solar corona, pushing the boundaries of how astronomers model solar flares. The Inouye Solar Telescope has provided high-resolution imagery that allows scientists to scrutinize features invisible to prior observational efforts, offering a new window into the dynamics of our closest star.

Coronal loops are massive structures of plasma that trace the Sun’s magnetic field lines and often precede powerful solar flares. These flares release energy in bursts that can disrupt Earth’s technology and power infrastructure. By observing the Sun at the H-alpha wavelength of 656.28 nm, which highlights specific solar features, the Inouye Telescope reveals intricate details crucial for understanding solar dynamics, something that other telescopes have previously struggled to achieve.

Lead author Cole Tamburri, who is pursuing a Ph.D. at the University of Colorado Boulder, expressed the significance of this historic observation, noting it was the first time the Inouye Solar Telescope had captured an X-class flare. The observing conditions during this event were ideal, showcasing the telescope’s capabilities in a way that had previously only been theoretical. This marks a watershed moment not only for the Inouye research team but for the broader scientific community grappling with solar physics.

A collaborative effort among scientists from various institutions including the Laboratory for Atmospheric and Space Physics (LASP), the Cooperative Institute for Research in Environmental Sciences (CIRES), and CU culminated in the groundbreaking findings. The telescope’s ability to observe ultra-fine magnetic field loops revealed a wealth of information about the structure of solar flares and their underlying magnetic fields. The average size of these loops mirrors the theoretical predictions that ranged from 10 to 100 kilometers in width, a range that had previously eluded observational confirmation.

Moreover, the Visible Broadband Imager (VBI) onboard the Inouye Solar Telescope can discern features as small as 24 kilometers, a feat that surpasses the capacity of existing solar telescopes by over two and a half times. This level of resolution is essential for understanding the intricate details that dictate solar dynamics and energy release during flares. The images demonstrate not only the complexity of solar activity but also the innovative technology that makes this research possible.

Despite the original focus on studying chromospheric spectral line dynamics, the unexpected discovery of ultra-fine coronal loop structures emerged as a significant finding that could enhance theoretical flare models. The research team was pleasantly surprised to encounter such intricate details about coronal structures that shed light on the complex physical processes involved in solar flaring and the magnetic interactions at play.

The potential implications of this research are profound. By revealing the smallest structures in the solar corona, researchers are now positioned to analyze not only their size but also their evolution and intricate dynamics. The ability to observe these fundamental building blocks of flare structures may provide insights into magnetic reconnection phenomena, which are central to the energy release mechanisms of solar flares.

Observing the imagery captured during this event is a remarkable experience; the fine thread-like loops sharply contrast against bright flare ribbons, showcasing an almost iridescent beauty that captivates both scientists and enthusiasts alike. This discovery signals an essential leap in solar science, illustrating the extent to which advanced observational tools can deepen our understanding of solar activity.

In conclusion, the NSF Daniel K. Inouye Solar Telescope has revolutionized our perspective on solar physics, allowing for the observation of fine structures that were previously mere conjectures. Through the unprecedented imagery and data generated by this telescope, scientists now have a unique opportunity to unravel the complexities of solar flares and their impact on Earth’s space weather, ushering in a new era of solar exploration and understanding.

The findings of this research and the significant implications for our understanding of the Sun are documented in the paper titled “Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST,” which has been published in The Astrophysical Journal Letters, marking a key contribution to solar science.

Subject of Research: Solar Flare Imaging
Article Title: Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST
News Publication Date: 25-Aug-2025
Web References: http://nso.edu
References: The Astrophysical Journal Letters
Image Credits: NSF/NSO/AURA

Keywords

Solar flares, coronal loops, solar imaging, Inouye Solar Telescope, solar physics, space weather.

Type III radio bursts are characterized by rapid frequency drifts and are predominantly generated at the local electron plasma frequency and its harmonics. The plasma frequency, denoted as ( \omega_p ), reflects the collective oscillation frequency of electrons in the plasma and is a fundamental parameter controlling wave propagation in space plasmas. The electron beams that catalyze these bursts instigate a turbulent cascade of electrostatic waves—primarily Langmuir waves—in the solar corona and solar wind. These intense wave populations then give rise to electromagnetic emissions spanning a broad frequency range, forming the observable radio burst signatures long detected by Earth-based radiotelescopes and spacecraft missions.

However, the solar plasma environment through which these radio waves propagate is far from uniform. It is permeated by a magnetic field that splits the emitted electromagnetic radiation into three principal modes: the extraordinary (X) mode, the ordinary (O) mode, and the Z mode. Each of these modes possesses unique dispersion relations, polarization characteristics, and radiation properties dictated by the plasma’s magneto-ionic environment. Consequently, the journey of any given electromagnetic wave mode from its birthplace near the electron beam to the distant observer is fraught with challenges, including potential mode conversion, absorption, and scattering caused by the randomly inhomogeneous plasma conditions.

The new study employs an interdisciplinary approach to unravel these complexities by combining large-scale particle-in-cell (PIC) simulations, sophisticated theoretical models of waves propagating in random media, and rigorous analytical calculations within the framework of turbulence theory. This trifecta of methodologies enables a comprehensive and quantitatively robust examination of how electromagnetic energy is partitioned among the modes and what fraction of this energy actually escapes the source region to be detected in situ by spacecraft or remotely by ground-based observatories.

Remarkably, Krafft et al. find that only a small fraction—no more than 10%—of the electromagnetic energy produced at the electron plasma frequency is able to escape the immediate vicinity of the beam-driven radio source. The majority of the radiated energy, according to their simulations and theory, is trapped predominantly in the Z mode. This mode, while energetically dominant locally, is confined close to the source region and does not efficiently propagate through the solar wind to distant observing platforms. This finding resolves longstanding puzzles in the interpretation of radio burst observations, where the inferred radiated energy appeared inconsistent with estimates of beam energetics and plasma conditions.

Among the escaping energy, the dominant contributors are the O mode waves, with the X mode waves contributing variably depending on specific plasma parameters such as magnetic field strength, plasma density, and turbulence levels. This mode-dependent escape efficiency is critically important for understanding the polarization patterns and spectral characteristics of solar radio bursts captured by state-of-the-art spacecraft such as Parker Solar Probe and Solar Orbiter, which offer unprecedented proximity to the Sun’s radio source regions.

The influence of plasma inhomogeneities and magnetic field complexities within the solar wind dramatically affects the efficiencies of these modes. The inhomogeneous plasma not only modulates the growth rates of electrostatic wave instabilities but also impacts the nonlinear coupling processes responsible for electromagnetic wave generation. In turbulent and magnetically complex regimes, wave refraction, scattering, and mode conversion become significant, effectively limiting the radiative efficiency for the X and O modes while confining much of the electromagnetic energy within trapped or evanescent plasma wave modes.

This study’s results uphold and extend the theoretical foundation initially laid by magneto-ionic theory and plasma turbulence models, providing a rigorous and quantitative framework that integrates simulation data with analytic insights. Such a synthesis represents a significant advance over prior studies, which often relied on idealized assumptions or incomplete representations of the solar plasma environment. By capturing the critical physical ingredients influencing wave mode propagation and escape, these new findings bring us closer to accurately diagnosing solar radio burst sources and the plasma conditions therein.

For spacecraft missions flying close to the Sun, including Parker Solar Probe and Solar Orbiter, the distinction between locally trapped wave modes and those capable of escaping into the interplanetary medium is crucial. The ability to distinguish O mode and X mode emissions from the Z mode background enables refined interpretation of in situ radio measurements and a better grasp of the beam–plasma interactions occurring near the Sun. Moreover, linking observational data with theoretical predictions enhances the utility of radio bursts as remote diagnostic tools for plasma densities, magnetic fields, and turbulence levels in the near-Sun heliosphere.

From a broader perspective, understanding the radiation efficiency of beam-generated electromagnetic waves has ramifications beyond solar physics. Similar plasma processes appear throughout astrophysical environments, including planetary magnetospheres, pulsar magnetospheres, and laboratory plasma devices. Thus, the insights from this study can inform a wide range of plasma applications, helping to unify our conceptual frameworks for wave generation, propagation, and energy confinement in magnetized, turbulent plasma media.

The methods employed in the study—especially the particle-in-cell simulations—offer a compelling demonstration of how numerical experimentation can illuminate the nonlinear microphysics underlying macroscopic plasma emission phenomena. By resolving electron beam dynamics, wave-particle interactions, and mode couplings self-consistently, the simulations bridge scales from microscopic plasma instabilities to the macroscopic signatures observable by remote sensing instruments.

The theoretical model of waves in a random medium, derived in this work, introduces critical corrections to classical dispersion relations by explicitly incorporating stochastic plasma density fluctuations and magnetic turbulence. These refinements enable more realistic predictions of wave propagation and absorption metrics, thereby advancing our capacity to model the solar corona and solar wind with enhanced fidelity.

Analytical calculations grounded in turbulence theory further elucidate the statistical properties of wave modes and their interactions, revealing how nonlinear wave-wave coupling and scattering processes redistribute energy among modes and dictate the resultant emission spectrum’s shape. Together with simulation results and theory, these analytical insights form a cohesive picture of how beam-driven plasma turbulence ultimately governs the patterns of observed solar radio emission.

The cumulative insights from Krafft and colleagues’ study not only produce a foundational understanding of radio burst radiation efficiencies but also pave the way for next-generation models and data analysis frameworks. These will allow the solar and space physics community to leverage radio burst data as reliable diagnostics of dynamic plasma conditions and energy transport processes in the Sun’s atmosphere and beyond.

As the solar cycle progresses and new high-resolution radio measurements become available, the findings reported here will be instrumental in interpreting complex radio burst features and correlating them with in situ plasma measurements. This synergy promises transformative advances in the predictive capabilities of space weather, with tangible benefits for satellite operations, telecommunications, and astronaut safety.

In summary, this research marks a pivotal advancement in our understanding of the intricate dance between electron beams, turbulent plasma waves, and electromagnetic modes in beam-generated solar radio sources. By dissecting the fate of electromagnetic energy among the X, O, and Z modes and clarifying the conditions enabling efficient radiation escape, Krafft et al. provide an essential key to unlocking the rich information encoded in solar radio bursts. This breakthrough not only enhances our scientific grasp of solar plasma processes but also empowers future explorations and technological endeavors reliant on space weather forecasting.

Subject of Research: Radiation efficiency and mode propagation of electromagnetic waves emitted during type III solar radio bursts generated by electron beams in the solar corona and solar wind.

Article Title: Radiation efficiency of electromagnetic wave modes from beam-generated solar radio sources

Article References:
Krafft, C., Volokitin, A.S., Polanco-Rodríguez, F.J. et al. Radiation efficiency of electromagnetic wave modes from beam-generated solar radio sources. Nat Astron (2025). https://doi.org/10.1038/s41550-025-02619-2

Image Credits: AI Generated

The mission, titled Auroral Waves Excited by Substorm Onset Magnetic Events, or AWESOME, epitomizes collaborative scientific investigation, combining the expertise of researchers from the University of Alaska Fairbanks (UAF) with the technological prowess of NASA’s Wallops Flight Facility. By launching a sequence of rockets designed to measure how energy and heat are distributed in the thermosphere following substorm activity, this initiative aims to challenge prevailing theories about atmospheric behavior and composition during auroras.

During these substorms—which manifest as vibrant visual displays in the night sky—the aurora can release tremendous amounts of energy into the atmosphere. Current theories suggest that this energy primarily causes vertical motion in the upper atmosphere, which then leads to a continuous convective plume. However, Mark Conde, the lead investigator and a space physics professor at UAF, proposes a different model. He suggests that acoustic-buoyancy waves, which travel both vertically and horizontally from the auroral activity, play a more significant role in mixing air at these altitudes than previously understood. This could indicate that the impact of auroral events extends over a far broader area than researchers are currently able to measure.

The upcoming launches are meticulously planned to occur during a launch window from March 24 to April 6. This carefully orchestrated timing is aimed at maximizing the scientific yield from the experiment as it synchronizes with natural auroral occurrences. The plan includes launching two Terrier-Improved Malemute rockets and one Black Brant XII rocket within a compact three-hour timeframe. Each rocket has specific functions: the two two-stage rockets will map the atmospheric disturbances at two altitudes, while the four-stage rocket will operate at multiple points, thus gathering comprehensive data about wind movements and wave oscillations across the altitudes of interest.

Adding to the visual spectacle, colorful vapor tracers will be released from these rockets, providing not only measurable data but a stunning display that will likely be visible from much of northern Alaska. As these tracers interact with the upper atmosphere, they will provide critical insights into the changes occurring in the atmospheric composition. This data collection is further enhanced by on-ground monitoring efforts coordinated by UAF graduate student researchers stationed at various strategic locations, which will contribute to a more extensive understanding of the thermosphere’s dynamics.

One of the most compelling elements of this research is the implications for understanding atmospheric stability. The thermosphere is traditionally viewed as a convectively stable region due to its temperature structure. The warmer air rises to the top, limiting vertical movement. However, the injection of energy from auroral substorms disrupts this stability. This disruption may lead to new mixing mechanisms within the thermosphere, fundamentally altering our understanding of this atmospheric layer’s behavior in response to external energy inputs.

In a world increasingly dependent on satellite technology, the importance of understanding and predicting space weather cannot be overstated. Disruptions caused by solar flares or geomagnetic storms can have catastrophic effects on communication systems, navigation, and even power grids. By learning more about how auroras affect atmospheric dynamics, scientists aim to incorporate these insights into more robust space weather forecasting models. Improved prediction capabilities will provide critical information for the aerospace industry, telecommunications, and even daily consumer electronics.

The AWESOME mission also represents a critical advancement in how atmospheric science views the interplay between solar phenomenon and terrestrial effects. Confirming the role of acoustic-buoyancy waves in thermospheric mixing could alter the trajectory of future research, prompting scientists to reevaluate existing models and methods of analysis. It embodies the spirit of inquiry, as researchers challenge established norms to uncover a deeper understanding of our atmospheric system and its connection to the cosmos.

The significance of these findings extends beyond academic interest. They may prompt engineers and technologists to consider the atmospheric variables when designing satellite systems or instrumentation intended for space. As such, the outcomes of this research could have far-reaching effects on how we approach satellite technology and resilience against the naturally fluctuating dynamics of Earth’s upper atmosphere.

In conclusion, the upcoming NASA-funded rockets’ launches not only promise a wealth of scientific data but also have the potential to transform our understanding of atmospheric dynamics in relation to auroral activity. The experimentation’s dual focus on empirical observation and theoretical questioning positions it at the forefront of current atmospheric research. As we venture into a future reliant on satellite technology, the lessons learned from this mission may equip us with the tools necessary to navigate and mitigate the atmospheric challenges that lie ahead.

Subject of Research: Interaction between auroral substorms and the Earth’s upper atmosphere
Article Title: NASA’s AWESOME mission to Reveal Secrets of the Thermosphere
News Publication Date: March 2024
Web References: NASA
References: Not applicable
Image Credits: NASA/Rachel Lense; NASA/Lee Wingfield

Keywords

auroras, thermosphere, space weather, NASA, atmospheric research, acoustic-buoyancy waves, geomagnetic activity, rocket launches, atmospheric dynamics