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.
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.
Understanding star and planet formation in extreme environments is crucial for uncovering the origins of our solar system. While most knowledge comes from nearby, isolated regions such as Taurus and Lupus, over half of all stars and planetary systems form in environments exposed to strong far-ultraviolet (FUV) radiation emitted by massive OB stars, with energies below the Lyman limit (E <13.6 eV).
NGC 6357—a young (~1–1.6 Myr), massive star-forming complex located 1690 pc away and hosting over 20 O-type stars—provides a unique opportunity to study the effects of FUV radiation on protoplanetary disks. This is the focus of the XUE (eXtreme UV Environments) collaboration.
Here, we present results from XUE2, a disk in the Pismis 24 cluster, based on spectra from JWST/MIRI and VLT/FORS2, complemented by photometric data. We first characterize the central star through spectrophotometric fitting, a fundamental step since protoplanetary disks are shaped by their host stars.
To evaluate the potential for rocky planet formation, we conduct a molecular and mineralogical analysis of the disk. We identify CO and CO₂ and report a tentative detection of CH₃⁺, key molecules for organic chemistry. Additionally, we identify predominantly amorphous silicates, as well as crystalline species such as enstatite and forsterite—molecules and minerals also observed in disks exposed to lower irradiation levels.
These findings offer new insights into the composition of inner disk regions under strong FUV irradiation, helping to constrain the formation conditions of rocky planets in massive clusters—an essential contribution to understanding the origins of the diverse exoplanets observed today.
How to cite: Lemus Nemocon, M. A., Ramírez-Tannus, M. C., and Higuera Garzón, M. A.: Molecular and Crystalline Structures in a Highly Irradiated Protoplanetary Disk in NGC 6357, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21494, https://doi.org/10.5194/egusphere-egu26-21494, 2026.
The probability of long-term survival of putative life on exoplanets has direct implications for the prevalence of extant life elsewhere. Environmental stability can be greatly attributed to abiotic features of a planetary body. However, we know that Earth’s current state is largely the result of life. Untangling biotic and abiotic influence, though, from Earth's deep history is difficult. To study these phenomena, we turn to computer simulation. We utilize, modify, and, in some cases, combine Planets Model Code (Tyrrell 2020), Tangled Nature Model (Christensen et al. 2002), and Daisy World (Watson & Lovelock 1983) to conduct a series of computer experiments. First, we modify and utilize Planets Model Code (Tyrrell 2020) to investigate worlds that harbor passive biota, which can only affect the environment in a random and unchanging manner over time. In this model, findings from a moderate sample study suggest that the probability of survival ( ps ) of life grows considerably with the increase in life's viable temperature range ( ΔT ) and follows the power law: ps ∝ ΔT 4. Also, we find that the chances of survival of any life on a given planet decrease linearly with time. Finally, we discern that the chances of survival of eukaryotic analogues remain low regardless of their emergence time in a planet's history. We complement these findings with two additional studies. Our current endeavor is to create a new model that adds an active set of evolving and competing species which can affect temperature only on a local scale and temporary basis. To build this adaptive ecology simulation, we modify and merge Planets Model Code (Tyrrell 2020) and Tangled Nature Model (Christensen et al. 2002). Planets Model Code (Tyrrell 2020) is utilized to simulate the climactic characteristics of the exoplanet. Tangled Nature Model (Christensen et al. 2002), which is utilized to run the ecological evolutionary model, operates in the form as modified by Arthur and Nicholson (2023), but with a few additional modifications of our own. Findings from this effort are soon forthcoming. Finally, we comment on plans for a future study, in which we propose a separate model wherein an active ecosystem is the dominant driving force in the stability, or lack thereof, of its home planet. By assessing ps in these limiting cases, we seek to understand if life can be a driver of planetary environmental stability.
References:
Arthur, Rudy and Arwen Nicholson (2023). “A Gaian Habitable Zone”. In: Monthly Notices of the Royal Astronomical Society 521.1. Publisher: Oxford University Press, pp. 690–707.
Christensen, Kim et al. (2002). “Tangled Nature: a Model of Evolutionary Ecology”. In: Journal of Theoretical Biology 216.1. Publisher: Elsevier, pp. 73–84.
Tyrrell, Toby (Oct. 2020). Planets Model code. DOI: 10.5281/zenodo.4081451.
Watson, Andrew J. and James E. Lovelock (Jan. 1983). “Biological Homeostasis of the Global Environment: the Parable of Daisyworld”. In: Tellus B: Chemical and Physical Meteorology 35.4, p. 284. ISSN: 1600-0889, 0280-6509.
How to cite: Evans, J., Lingam, M., and Riousset, J.: Biotic Factors in Long-Term Planetary Habitability, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14528, https://doi.org/10.5194/egusphere-egu26-14528, 2026.
Stable isotopes of oxygen and hydrogen are a powerful multipurpose tool widely used across multiple disciplines in Earth and Planetary sciences. In hydrology, δ18O and δ2H in the water molecule are commonly used in stream water source apportionment and transit time analyses. In paleoclimate research, ice core water isotope records are used as a temperature proxy, documenting past climate variability over hundreds of thousands of years. Oxygen and hydrogen isotopes are also versatile fingerprints for retracing the formation of planets and other celestial bodies.
These examples should not obscure the fact that many unknowns and uncertainties remain inherent to the use of stable isotopes of O and H as tracers and fingerprints of processes in terrestrial and extra-terrestrial environments. To this date, only a few experimental studies have investigated water ice sublimation rates and the effect of isotopic fractionation processes – notably on water ice under lunar environmental conditions.
Here we present results from a combined experimental and modelling approach. With an instrumental set-up developed at LIST, we simulate the sublimation of water ice under extreme environmental conditions (very high vacuum and/or very low temperatures) with the goal of exploring O-H isotopic fractionation processes in both (extreme) terrestrial and extraterrestrial environments. An understanding of these processes is necessary for interpreting the isotope signatures of water in planetary exploration missions, such as ESA’s PROSPECT project for lunar exploration, and in terrestrial hydrology of cold regions.
The current experimental setup consists of a sublimation chamber capable of operating at pressures down to 10⁻⁶ Pa and temperatures as low as 110 K, with high stability and control over sublimation conditions. The system can simulate controlled environments for the phase transition of water (ice-vapor), isotopic fractionation, and the movement of water vapor across different phases of the experimental run. This includes transferring gas to a series of parallel cold traps, analyzing isotopic content using laser spectroscopy.
We have developed a stochastic lagrangian numerical model to verify the existing theories of phase transition, diffusion, and O-H isotopic fractionation based on the Langevin equation. The model allows for sublimation, diffusive transport, and condensation of water and its isotopes through an isothermal domain representing the volume of the experimental prototype. Lagrangian models are highly adaptive for handling complex boundary conditions and well-suited for solving fluid mechanics problems with various types of particles.
A sensitivity analysis of the model using different sublimation temperatures shows consistent results with our experimental data. Results obtained from the dual isotope analysis (δ¹⁸O and δ²H) of ice samples obtained from Greenland Summit Precipitation (GRESP) and Antarctica snow show trends consistent with theoretical predictions and meteoric water line, suggesting that the setup is operating reliably. Observed deviations in the isotopic compositions indicate influences from environmental variables such as humidity, pointing towards the need for tighter control and validation. Our experimental set-up lays a foundation for further investigations into the problems of fast diffusion, non-equilibrium thermodynamics, and the isotopic signature of water.
How to cite: Kumawat, M., Barnich, F., Pfister, L., Zehe, E., and Hadler, K.: Water ice sublimation and O-H isotopic fractionation in terrestrial and extraterrestrial environments: new insights gained from numerical modelling and laboratory experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23186, https://doi.org/10.5194/egusphere-egu26-23186, 2026.
Earth’s Moon is really big. Both the satellite and the giant impact that created it have played key roles in our planet’s evolution into a life-supporting world; stabilising the planet’s spin for a consistent climate, and driving the ocean tides that could stimulate prebiotic chemistry. Giant impacts are common across planet formation. So, as observational techniques improve, we might expect to find large moons among the now thousands of detected exoplanets, many of which are more massive than Earth. A barrier to this is that giant impacts onto larger planets create hotter debris disks of mostly vapour, especially for ice-rich worlds. This gas would drag any small growing moonlets to rapidly spiral down to the planet, prohibiting any large moons from forming out of the disk.
However, using high-resolution 3D smoothed particle hydrodynamics (SPH) simulations of giant impacts, we find that big moons can be immediately placed onto wide orbits, safely outside the thick, dragging disk. This could allow large rocky and even large icy worlds to gain a big moon.
This impact scenario had previously been demonstrated as an option for forming Earth’s Moon, for a limited range of tested parameters. Here we identify multiple regions of parameter space across which large immediate satellites can form (of order 1% the mass of the planet), for target planets ranging from 0.5 to 10 Earth masses, inclusive. We also confirm consistent results using the new SPH scheme REMIX, designed to improve the treatment of mixing and discontinuities in impact simulations. Furthermore, the rate of increase of the vapour mass-fraction with the system mass depends on the impact scenario, such that the post-impact disks of even the largest of these planets may not be fully vaporised.
Large moons may still be uncommon in general, but giant impacts offer a pathway for Super-Earths and even mini-Neptunes to gain fractionally massive satellites and the potential benefits of one for life.
How to cite: Kegerreis, J., Eke, V., Sandnes, T., and Davies, H.: A rapid route for even big planets to get big moons, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14985, https://doi.org/10.5194/egusphere-egu26-14985, 2026.
