Posters virtual: Thu, 7 May, 14:00–18:00 | vPoster spot 4
Interpreting the response of the magnetosphere to solar wind driving is being historically limited by the sparse measurements of upstream conditions. Recent investigations, using multiple upstream monitors, revealed that properties of the solar wind are often non uniform on spatial scales comparable to the size of the Earth’s magnetosphere. This aspect remarks the limitation of the common assumption of the impact of a uniform solar wind front based on single probe observations. Here, we perform a critical investigation of a case study in which a particular solar wind mesoscale structure, in the form of a periodic density structure (PDS), shows coherence on a limited extent of the Earth’s upstream region. First, we examine the possible reasons behind discrepancies in the measurements among different solar wind monitors. Then, we discuss the response of the magnetosphere in terms of Ultra-Low-Frequency (ULF) waves based on properties of the solar wind driver including the periodicities of the PDSs, the extent of their spatial coherence, and the associated interplanetary magnetic field properties.
How to cite: Di Matteo, S., Recchiuti, D., and Villante, U.: Magnetosphere response to a spatially non-uniform solar wind stream, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15149, https://doi.org/10.5194/egusphere-egu26-15149, 2026.
On 11 November 2025, Solar Orbiter’s STIX instrument observed an X5-class solar flare, which peaked at approximately 10:01 UTC, originating from active region AR 14274 located at N23W23. Associated with this flare, a fast coronal mass ejection (CME) was observed by several coronagraphs, with a reconstructed 3D speed of about 2100 km s⁻¹. Solar Orbiter, near 0.82 au and ~18° west of Earth in heliolongitude, encountered the associated interplanetary CME (ICME) at around 09:00 UTC on 12 November, as observed by the MAG and SWA instruments. The ICME arrived at Earth roughly 9 hours later, around 18:00 UTC on 12 November.
Solar Orbiter/EPD detected electrons with energies above 7 MeV, as well as penetrating ions exceeding 400 MeV. At Earth, the neutron monitor network recorded the ground level enhancement 77 (GLE 77), showing increases at least above a rigidity of 8 GV shortly after 10:00 UTC on 11 November. This event represents the largest GLE of Solar Cycle 25 observed to date and displays clear prompt and delayed components, presumably associated with flare-related and CME-driven particle acceleration.
In this study, we analyze Solar Orbiter and near-Earth observations of the flare, CME, and associated solar energetic particle (SEP) event. We also include multi-spacecraft SEP measurements, in particular from ESA’s BepiColombo mission, which was nominally well connected to the parent active region.
How to cite: Rodríguez-García, L., Rodríguez-Pacheco, J., Wimmer-Schweingruber, R., Ho, G., Gómez-Herrero, R., Espinosa Lara, F., Cernuda, I., Mason, G., Lario, D., Trotta, D., Dresing, N., Kouloumvakos, A., Warmuth, A., Müller, D., Janvier, M., Jones, G., Besse, S., Witasse, O., Markovic, J., and Gomes, A. and the Study team: Solar Orbiter observations of the largest ground level enhancement of Solar Cycle 25 to date (GLE 77), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5972, https://doi.org/10.5194/egusphere-egu26-5972, 2026.
How to cite: Liu, W.: An important medium for ion energization and non-thermal ions' energy release in the near-Sun solar wind: ion-scale waves , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-266, https://doi.org/10.5194/egusphere-egu26-266, 2026.
MEGA-H is a multi-detector, wide-field telescope system that produces ultra-high-resolution, seamless images. The optical path employs pickoff mirrors that partition the image field onto three individual detectors. The detectors can be located conveniently apart from each other while preserving the whole FOV and producing a recombined image without any gaps. This architecture enables a scientist to choose the best detector for the task, which may have the good detection properties but insufficient number of pixels, and combine multiple detectors to achieve the desired pixel count. This camera system will initially be mounted behind a wide FOV white light imager and be capable of both wide FOV (10 degrees on diagonal) and high instantaneous field of view (iFOV) (<1.5”) to observe the Sun’s corona.
We describe our progress in assembling and testing the instrument, which is built around COTS telescope optics and camera heads. Alignment features facilitate fine positioning of the two pickoff mirrors and three camera heads. Stray light control features prevent ‘sneak path’ rays from falling on the wrong detector. The instrument is designed to work in an airborne environment. A thermal control subsystem incorporates four thermal zones, to maintain tight focus and alignment under dynamic environmental conditions, while a focus mechanism compensates for large changes in temperature. The data path is sized to store full-resolution data from three 127 Mpixel cameras, at a rate of 10 GB/s. A real time viewer produces fused images from the three cameras for monitoring of the image acquisition process.
MEGA-H is sponsored by HESTO, NASA’s Heliophysics Science and Technology Office.
How to cite: Eskin, J., Caspi, A., DeForest, C., Oakley, P., Brown, B., Finch, T., Frye, J., Lage, J., Sharma, J., Speck, R., Spuhler, P., and Turner, R.: Status of MEGA-H: An Ultra-Wide-Field Camera for Heliophysics Applications, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15364, https://doi.org/10.5194/egusphere-egu26-15364, 2026.
The plasma wave instruments on both Voyager spacecraft have observed electron plasma oscillations in the very local interstellar medium (VLISM). The generally accepted explanation of these events is that the electron foreshock of shocks in the VLISM comprise electron beams in the range of 10 to 100 eV that are unstable to Langmuir waves, or electron plasma oscillations. Further, at least some of these events have been tied to solar transients departing the Sun more than a year earlier that evolve as they propagate outward. These disturbances are led by shocks and the impulse of these on the heliospause results in some of the shock impulse continuing into the VLISM. Previously, Voyager 1 had detected the most distant evidence of these transients at about 145 AU. In August 2025 Voyager 2 detected electron plasma oscillations near 140 AU. A simple model of the propagation of this disturbance suggests a transient from the Sun in 2022 as its source, near the beginning of the current solar maximum. New Horizons observed a series of shocks in 2022 – 2023 at heliocentric distances near 55 AU that could be related to the Voyager 2 event. Given these events occur early in solar cycle 25, it is possible additional shocks will be detected by Voyager and enable us to extend the distance over which these disturbances can travel in the VLISM.
We further relate some of the transients observed by the Voyager plasma wave instruments to global models of the VLISM density and magnetic field (Fraternale et al., 2026). For example, these models show the increased density and magnetic field associated with the so-called pf2 (pressure front 2) described by Burlaga et al. (2021). We can now show that the 2-3 kHz radio emissions observed by the Voyagers in the early 1980’s, 1990’s, and 2000’s are related to density structures just beyond the heliopause presumed to be associated with global merged interaction regions stemming from very active solar conditions.
How to cite: Kurth, W., Jaynes, A., Fraternale, F., Kim, T., and Pogorelov, N.: Effects of solar transients observed in the VLISM , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4233, https://doi.org/10.5194/egusphere-egu26-4233, 2026.
