Manon Jarry

Aims. Solar Orbiter observations provide an unprecedented opportunity to study solar energetic particle (SEP) events at heliocentric distances ≲1 au. In this work, we compile a catalogue of SEP events, utilising Solar Orbiter measurements. Methods. The catalogue is based on measurements from the High Energy Telescope (HET) of the Energetic Particle Detector (EPD) instrument suite on Solar Orbiter during the ascending phase of solar cycle 25 (2020–2025). We performed a parallel survey of near-relativistic electrons (∼1 MeV) and protons (∼8 MeV), identifying particle enhancements above background levels and registering SEP events. For each SEP event and particle species, we calculated the SEP characteristics (e.g. onset and peak times, peak intensity values, the fluence, and e/p intensity ratios). Our analysis techniques included a velocity dispersion analysis (VDA) and time-shifting analysis (TSA) to infer the SEP release times at the Sun. We compared the SEP release times with solar flare observations from the Spectrometer Telescope for Imaging X-rays (STIX) and X-Ray Sensor (XRS) on Geostationary Operational Environmental Satellites (GOES) and identified the parent solar sources. We also identified the associated coronal mass ejections (CMEs). The SEP events were cross-checked with magnetic field and solar wind data from the Solar Wind Analyser (SWA) and Magnetometer (MAG) and the relevant plasma quantities were tabulated. In addition, the connection angle (CA) for each event was calculated and reported. Results. Our catalogue includes 177 SEP events. The present study focuses on both electron and proton events, with 50 of these events exhibiting high-energy protons (∼50 MeV). A strong correlation is found between peak intensity and fluence for both electrons ( cc = 0.86 ± 0.03) and protons ( cc = 0.95 ± 0.02). Using the CA, events were classified as well-connected (±20°) and poorly connected. The SEP peak fluxes and fluences show weak correlations with flare soft X-ray peak flux ( cc ∼0.17-0.21), while stronger correlations are observed with a CME projected speed for well-connected events ( cc ∼ 0.61 for electrons and ∼0.47 for protons). Across all events with a measurable electron-to-proton (e/p) ratio, the ratio spans more than three orders of magnitude and forms a continuous distribution, with no clear distinction between impulsive and gradual populations. Combined with compositional information, higher e/p ratios are generally associated with ³ He-rich and Fe-rich events and lower values with shock-driven events, although a significant overlap exists. Finally, scaling relations reveal an energy dependence: low-energy protons (∼8-25 MeV) are influenced by both magnetic connectivity and source composition, whereas high-energy protons (∼50 MeV) are primarily governed by source composition ( ³ He and Fe signatures).

Context. The SPEARHEAD (specification, analysis, and re-calibration of high-energy particle data) project, funded by the European Union’s Horizon Europe programme, enhances the accuracy and usability of high-energy particle measurements. It investigates particle acceleration, release, and transport during solar eruptions by refining instrument response functions and cross-calibrating datasets. This effort supports in-depth analyses of solar energetic particle (SEP) events and provides public data products. Aims. We present a comprehensive catalogue of > 100 MeV proton events identified from May 1996 to August 2024 using SOHO/ERNE penetrating-particle rates, together with associated solar phenomena derived from multi-instrument observations. Methods. The SEP events were detected through a systematic scan of ERNE/HED counter data and cross-calibrated with SOHO/EPHIN to derive peak fluxes and fluences. Each event was associated with its likely parent eruption using X-ray (XR) (GOES/XRS, RHESSI, SolO/STIX), radio (Wind/WAVES, STEREO/WAVES, ground-based observatories), and γ -ray (Fermi/LAT) observations, CMEs (SOHO/LASCO), and ground-level enhancements (GLEs) (neutron monitors). Timings and physical properties were systematically compared to investigate the relationships between SEP onset, flare evolution, CME kinematics, and radio signatures. Results. Associations were established for 96% of CMEs and 76% of X-ray flares; all events exhibited type III radio bursts, while 95% had type II, and 53% type IV. > 100 MeV γ -rays were identified in 65 events, and 22 were linked to GLEs or sub-GLEs. Statistical analyses reveal that most SEP releases closely follow flare and CME onsets, with moderate SEP-XR-CME correlations, and a strong SEP-GLE fluence link. These results indicate that high-energy SEP events are typically associated with strong solar activity signatures, with the observed intensities and timings strongly modulated by magnetic connectivity and coronal conditions. Conclusions. This catalogue provides the most extensive reference to date for high-energy SEP events over solar cycles 23–25, establishing a unified framework for future investigations of extreme particle acceleration.

La formation et la propagation des éjections de masse coronale (CMEs) peuvent générer des ondes de choc dans la couronne solaire. Ces ondes de choc peuvent mener à des orages géomagnétiques très intenses et modifier les flux de particules énergétiques dans l'héliosphère interne. Les "flares" solaires générés par la reconnexion magnétique sont également des accélérateurs efficaces de particules. Les ondes de choc et les flares survenant simultanément, il est difficile d'isoler les contributions relatives de ces accélérateurs de particules à très haute énergie. Dans le but d'améliorer notre compréhension de ces processus d'accélération, cette thèse examine la relation intriquée entre les ondes de choc poussées par les CMEs, leurs flares associés et les événements à particules énergétiques solaires (SEPs) résultants. Des techniques d'observation et de modélisation sont nécessaires pour isoler les effets de chaque source. Les données obtenues des missions STEREOs, SOHO, SDO, et plus récemment PSP et Solar Orbiter, offrent des mesures in-situ et des observations à distance de ces phénomènes complexes. L'évolution des ondes de pression/choc de la couronne solaire au milieu interplanétaire peut être modélisée par imagerie multipoints. Une étude paramétrique de 33 ondes de pression observées entre 2011 et 2017 et reconstruites par cette technique a été réalisée. Un profil standard d'expansion et de propagation des ondes de choc est établi, révélant une expansion quasi-sphérique durant la phase d'expansion initiale de la CME. Un facteur de correction est proposé pour prendre en compte les effets de projection dans les estimations de vitesse obtenues à partir d'un seul point de vue. L'étude des flux de rayons X mous et durs (SXR et HXR) émis par les flares associés à ces chocs a confirmé l'effet Neupert déjà connu et la forte corrélation entre leurs maxima. La vitesse de l'onde de choc est corrélée temporellement avec le SXR, et son accélération avec le HXR. Une relation déjà établie entre la vitesse radiale du choc et le maximum du flare SXR est mise à jour en incluant des CMEs très rapides. Dans celle-ci, tous les flares de classe X sont associés à des CMEs atteignant au moins 1000 km/s. Les propriétés magnéto-hydrodynamiques (MHD) du choc en expansion et les lignes de champ magnétique dans la couronne peuvent être dérivées en utilisant des simulations MHD. À mesure que le choc évolue, sa géométrie et sa cinématique se modifient rapidement le long des lignes de champ magnétique connectées aux satellites mesurant les SEPs. L'étude d'un événement particulier a révélé des corrélations entre l'évolution temporelle des paramètres du choc et les propriétés des événements SEPs associés. Une forte concordance temporelle est observée entre la formation du choc modélisé et les estimations des temps d'injection des électrons et des protons le long des lignes magnétiques considérées, suggérant un processus d'accélération commun. Le rapport électron/proton élevé en début d'événement SEP correspond à la phase quasi-perpendiculaire du choc. L'étude conjointe des rapports d'abondance comme Fe/C avec l'évolution de la géométrie du choc nous révèle que, contrairement aux résultats d'études antérieures, un ratio Fe/C élevé à haute énergie n'est pas toujours lié à une géométrie quasi-perpendiculaire du choc. En revanche, les observations suggèrent que l'activité solaire avant l'événement joue un rôle important dans la modification de la composition coronale locale, affectant ainsi la composition des SEPs indépendamment de l'efficacité de l'accélération des chocs. Avec l'utilisation de codes de transport de particules dans lesquels nous intégrons ces chocs, des comparaisons entre observations et simulations sont réalisées pour identifier les paramètres clés du choc dans le processus d'accélération.

On 21 November 2024, a strong solar energetic particle (SEP) event implying protons of 100 MeV near Earth was associated with an eruption located on the far side of the Sun as viewed from Earth.The source region was identified using EUV observations from the Solar-Terrestrial Relations Observatory (STEREO) as NOAA AR 13892, located around (lon, lat) = (355°, -20°) in Carrington coordinates at around 00:45 UT. Due to its location, the associated flare produced only weak soft X-ray signatures in Earth-based observations. The Spectrometer/Telescope for Imaging X-rays (STIX) instrument on-board Solar Orbiter, which was also positioned on the far side relative to the parent active region, recorded an increase in the 15-25 keV range. The flare was followed by a coronal mass ejection (CME) of speed 1436 km/s, propagating on the solar limb and driving a shock wave at its front. The 3D geometry of the CME-driven shock was reconstructed using white-light remote-sensing observations from STEREO-A and SOHO. This was then combined with global magneto-hydrodynamic (MHD) simulations from Predictive Science Inc. (PSI), to derive the MHD properties of the shock surface, as well as the magnetic field lines connecting the spacecraft to the Sun’s surface.This enables the study of MHD shock parameters evolution along field lines regarding the SEP profile and characteristics measured at the corresponding spacecraft. We therefore investigated acceleration scenarios for the energetic particles that reached Earth, STEREO-A and Solar Orbiter, which are magnetically connected to different regions of the evolving shock.

Context. The acceleration of particles at the Sun and their propagation through interplanetary space are key topics in heliophysics. Specifically, solar energetic electrons (SEEs) measured in situ can be linked to solar events such as flares and coronal mass ejections (CMEs) since they are also observed remotely in a broad range of electromagnetic emissions such as in radio and X-rays. Solar Orbiter, equipped with a wide range of remote-sensing and in situ detectors, provides an excellent opportunity to investigate SEEs and their solar origin from the inner heliosphere. Aims. We aim to record all SEE events measured in situ by Solar Orbiter, and to identify and characterise their potential solar counterparts. The results have been compiled in the Comprehensive Solar Energetic Electron event Catalogue (CoSEE-Cat), which will be updated regularly as the mission progresses. The catalogue contains key parameters of the SEEs, as well as the associated flares, CMEs, and radio bursts. In this paper, we describe the catalogue and provide a first statistical analysis. Methods. The Energetic Particle Detector (EPD) was used to identify and characterise SEE events, infer the electron release time at the Sun, and determine the composition of related energetic ions. Basic parameters of associated X-ray flares (timing, intensity, source location) were provided by the Spectrometer/Telescope for Imaging X-rays (STIX). This was complemented by the Extreme Ultraviolet Imager (EUI), which added information on eruptive phenomena. CME observations were contributed by the coronagraph Metis and the Solar Orbiter Heliospheric Imager (SoloHI). Type III radio bursts observed by the Radio and Plasma Waves (RPW) instrument provided a link between the SEEs detected at Solar Orbiter and their potential solar sources. The conditions in interplanetary space were characterised using Solar Wind Analyzer (SWA) and Solar Orbiter Magnetometer (MAG) measurements. Finally, data-driven modelling with the Magnetic Connectivity Tool provided an independent estimate of the solar source position of the SEEs. Results. The first data release of the catalogue contains 303 SEE events observed in the period from November 2020 until the end of December 2022. Based on the timing and magnetic connectivity of their solar counterparts, we find a very clear distinction between events with an impulsive ion composition and ones with a gradual one. These results support the flare-related origin of impulsive events and the association of gradual events with extended structures such as CME-driven shocks or erupting flux ropes. We also show that the commonly observed delays of the solar release times of the SEEs relative to the associated X-ray flares and type III radio burst are at least partially due to propagation effects and not exclusively due to an actual delayed injection. This effect is cumulative with heliocentric distance and is probably related to turbulence and cross-field transport.

Context. The interaction of the solar wind (SW) with the coupled magnetosphere-exosphere-surface of Mercury is complex. Charged particles released by the SW can precipitate along planetary magnetic field lines on specific areas of the surface of the planet. The processes responsible for the particle precipitation strongly depend on the orientation of the interplanetary magnetic field (IMF) upstream of Mercury. Aims. During the third Mercury flyby (MFB3) by BepiColombo, the properties of the SW inferred from BepiColombo observations of a highly compressed magnetosphere corresponded to those of a very dense plasma embedded in a slow SW. The Mercury Electron Analyzer (MEA) measured continuous high-energy electron fluxes in the nightside dawn sector of the compressed magnetosphere. In order to constrain further studies related to the origin of these populations, we aim to firmly confirm the initial inferences and detail the SW properties throughout MFB3. Methods. We took advantage of a close radial alignment between Parker Solar Probe (PSP) and Mercury. We monitored the activity of the Sun using SOHO coronagraphs and we used a potential field source surface model to estimate the location of the magnetic footpoints of PSP and BepiColombo on the photosphere of the Sun. We propagated the plasma parameters and the IMF measured by PSP at BepiColombo, to check if the plasma impacted Mercury. Results. We show that during MFB3, PSP and BepiColombo connected magnetically to the same region at the solar surface. The slow SW perturbation first measured at PSP propagated to Mercury and BepiColombo, as was confirmed by similarly elevated plasma densities measured at PSP and BepiColombo. The IMF orientation stayed southward during the whole MFB3. Conclusions. Our results provide strong constraints for future studies of the magnetospheric structure and dynamics during MFB3, including tail reconnection, electron and ion energization, and subsequent plasma precipitation onto the surface of Mercury.

High energy solar protons were observed by particle detectors aboard spacecraft in near-Earth orbit on May 11, 2024 and produced the 74^th ground level enhancement (GLE74) event registered by ground-based neutron monitors. This study involves a detailed reconstruction of the neutron monitor response, along with the identification of the solar eruption responsible for the emission of the primary particles, utilizing both in situ and remote-sensing. Observations spanning proton energies from a few MeV to around 1.64 GeV, collected from the Solar and Heliospheric Observatory (SOHO), the Geostationary Operational Environmental Satellite (GOES), the Solar Terrestrial Relations Observatory (STEREO-A), and neutron monitors, were integrated with records of the associated solar soft X-ray flare, coronal mass ejection, and radio bursts, to identify the solar origin of the GLE74. Additionally, a time-shift analysis was conducted to link the detected particles to their solar sources. Finally, a comparison of GLE74 to previous ones is carried out. GLE74 reached a maximum particle rigidity of at least 2.4 GV and was associated with a series of type III, type II, and type IV radio bursts. The release time of the primary solar energetic particles (SEPs) with an energy of 500 MeV was estimated to be around 01:21 UT. A significant SEP flux was observed from the anti-Sun direction with a relatively broad angular distribution, rather than a narrow, beam-like pattern, particularly during the main phase at the particle peak flux. Comparisons with previous GLEs suggest that GLE74 was a typical event in terms of solar eruption dynamics.

Context. On 13 March 2023, when the Parker Solar Probe spacecraft (S/C) was situated on the far side of the Sun as seen from Earth, a large solar eruption took place, which created a strong solar energetic particle (SEP) event observed by multiple S/C all around the Sun. The energetic event was observed at six well-separated locations in the heliosphere, provided by the Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO A, near-Earth S/C, and MAVEN at Mars. Clear signatures of an in situ shock crossing and a related energetic storm particle (ESP) event were observed at all inner-heliospheric S/C, suggesting that the interplanetary coronal mass ejection (CME)-driven shock extended all around the Sun. However, the solar event was accompanied by a series of pre-event CMEs. Aims. We aim to characterize this extreme widespread SEP event and to provide an explanation for the unusual observation of a circumsolar interplanetary shock and a corresponding circumsolar ESP event. Methods. We analyzed data from seven space missions, namely Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO A, SOHO, Wind, and MAVEN, to characterize the solar eruption at the Sun, the energetic particle event, and the interplanetary context at each observer location as well as the magnetic connectivity of each observer to the Sun. We then employed magnetohydrodynamic simulations of the solar wind in which we injected various CMEs that were launched before as well as contemporaneously with the solar eruption under study. In particular, we tested two different scenarios that could have produced the observed global ESP event: (1) a single circumsolar blast-wave-like shock launched by the associated solar eruption, and (2) the combination of multiple CMEs driving shocks into different directions. Results. By comparing the simulations of the two scenarios with observations, we find that both settings are able to explain the observations. However, the blast-wave scenario performs slightly better in terms of the predicted shock arrival times at the various observers. Conclusions. Our work demonstrates that a circumsolar ESP event, driven by a single solar eruption into the inner heliosphere, is a realistic scenario.

We report on multi-spacecraft measurements of a solar energetic particle (SEP) event that occurred on 13 March 2023. The Parker Solar Probe (PSP) mission was situated on the far side of the Sun as seen from Earth at a radial distance of only 49 solar radii and observed a very strong event including the associated CME and its shock passing over the spacecraft only four hours after the solar eruption. Solar Orbiter, BepiColombo, STEREO A, near-Earth spacecraft, and MAVEN at Mars were all situated within 50 degrees in longitude, and observed the event as well, proving its widespread character. Clear signatures of shock-driven energetic storm particle events were present at Solar Orbiter, STEREO A, and near-Earth spacecraft suggesting that the interplanetary CME-driven shock had a longitudinal extent of about 160 degrees. However, the solar event was accompanied by a series of pre-event CMEs and comparison with ENLIL simulation results suggest that the ESP events were associated with shocks driven by other CMEs. This scenario of particle re-acceleration at different pre-event-associated shocks, provides a new scenario for the generation of widespread SEP events.

Solar energetic particle (SEP) events, particularly those of significant magnitude, are commonly associated with fast and wide coronal mass ejections (CMEs). These CMEs generate and drive shock waves in the solar corona, proving to be highly efficient in particle acceleration to high energies. Understanding the intricate connections between shock wave properties and SEP characteristics is crucial for advancing Space Weather forecasting.To achieve this objective, we employ a methodology to analyze a SEP event involving a coronal shock wave, observed by several spacecraft well distributed around the Sun. Initially, we reconstruct the 3D ellipsoidal shape of the expanding shock, enabling the extraction of its geometry and kinematic properties. Using magneto-hydrodynamics (MHD) cubes, we then reconstruct the magnetic connectivity of spacecrafts and retrieve the MHD properties of the shock wave at the intersections with these magnetic field lines. The temporal correlations between the shock properties and the SEPs recorded by individual spacecraft can finally be compared.Through the application of this methodology, we identify enhanced correlation coefficients between SEPs and shock parameters, such as speed, Alfvénic Mach Number, and theta_BN (the angle between the shock's normal and the magnetic field line). This work is funded by the H2020 SERPENTINE project.