Sazuna/UAT_keywords huggingface dataset:
Uranus's Influence on Neptune's Exterior Mean-motion Resonances. Neptune's external mean-motion resonances play an important role in sculpting the observed population of trans-Neptunian objects (TNOs). The population of scattering TNOs is known to "stick" to Neptune's resonances while evolving in semimajor axis (a), though simulations show that resonance sticking is less prevalent at a ≳ 200–250 au. Here we present an extensive numerical exploration of the strengths of Neptune's resonances for scattering TNOs with perihelion distances q = 33 au. We show that the drop-off in resonance sticking for the large a scattering TNOs is not a generic feature of scattering dynamics but can instead be attributed to the specific configuration of Neptune and Uranus in our solar system. In simulations with just Uranus removed from the giant planet system, Neptune's resonances are strong in the scattering population out to at least ∼300 au. Uranus and Neptune are near a 2:1 period ratio, and the variations in Neptune's orbit resulting from this near-resonance are responsible for destabilizing Neptune's resonances for high-e TNO orbits beyond the ∼20:1 resonance at a ≈ 220 au. Direct interactions between Uranus and the scattering population are responsible for slightly weakening Neptune's closer-in resonances. In simulations where Neptune and Uranus are placed in their mutual 2:1 resonance, we see almost no stable libration of scattering particles in Neptune's external resonances. Our results have important implications for how the strengths of Neptune's distant resonances varied during the epoch of planet migration when the Neptune–Uranus period ratio was evolving. These strength variations likely affected the distant scattering, resonant, and detached TNO populations.

Keywords: Celestial mechanics, Resonant Kuiper belt objects, Orbital resonances, Trans-Neptunian objects
An Explainable Deep-learning Model of Proton Auroras on Mars. Proton auroras are widely observed on the dayside of Mars, identified as a significant intensity enhancement in the hydrogen Lyα (121.6 nm) emission at altitudes of ∼110 and 150 km. Solar wind protons penetrating as energetic neutral atoms into Mars' thermosphere are thought to be primarily responsible for these auroras. Recent observations of spatially localized "patchy" proton auroras suggest a possible direct deposition of protons into Mars' atmosphere during unstable solar wind conditions. Improving our understanding of proton auroras is therefore important for characterizing the interaction of the solar wind with Mars' atmosphere. Here, we develop a first purely data-driven model of proton auroras using Mars Atmosphere and Volatile Evolution (MAVEN) in situ observations and limb scans of Lyα emissions between 2014 and 2022. We train an artificial neural network that reproduces individual Lyα intensities and relative Lyα peak intensity enhancements with Pearson correlations of ∼94% and ∼60% respectively for the test data, along with a faithful reconstruction of the shape of the observed altitude profiles of Lyα emission. By performing a Shapley Additive Explanations (SHAP) analysis, we find that solar zenith angle, solar longitude, CO2 atmosphere variability, solar wind speed, and temperature are the most important features for the modeled Lyα peak intensity enhancements. Additionally, we find that the modeled peak intensity enhancements are high for early local-time hours, particularly near polar latitudes, and the induced magnetic fields are weaker. Through SHAP analysis, we also identify the influence of biases in the training data and interdependences between the measurements used for the modeling, and an improvement of those aspects can significantly improve the performance and applicability of the ANN model.

Keywords: Neural networks, Mars, Solar wind, Aurorae, Planetary magnetospheres
The Implications of Thermal Hydrodynamic Atmospheric Escape on the TRAPPIST-1 Planets. JWST observations of the seven-planet TRAPPIST-1 system will provide an excellent opportunity to test outcomes of stellar-driven evolution of terrestrial planetary atmospheres, including atmospheric escape, ocean loss, and abiotic oxygen production. While most previous studies use a single luminosity evolution for the host star, we incorporate observational uncertainties in stellar mass, luminosity evolution, system age, and planetary parameters to statistically explore the plausible range of planetary atmospheric escape outcomes. We present probabilistic distributions of total water loss and oxygen production as a function of initial water content, for planets with initially pure water atmospheres and no interior─atmosphere exchange. We find that the interior planets are desiccated for initial water contents below 50 Earth oceans. For TRAPPIST-1e, f, g, and h, we report maximum water-loss ranges of , , , and Earth oceans, respectively, with corresponding maximum oxygen retention of , , , and bars. We explore statistical constraints on initial water content imposed by current water content, which could inform evolutionary history and planet formation. If TRAPPIST-1b is airless while TRAPPIST-1c possesses a tenuous oxygen atmosphere, as initial JWST observations suggest, then our models predict an initial surface water content of 8.2 Earth oceans for these worlds, leading to the outer planets retaining &gt;1.5 Earth oceans after entering the habitable zone. Even if TRAPPIST-1c is airless, surface water on the outer planets would not be precluded.

Keywords: Extrasolar rocky planets, Exoplanet atmospheres, Exoplanets, Exoplanet atmospheric evolution
Laboratory Spectral Characterization of Ribbeck Aubrite: Meteorite Sample of Earth-impacting Near-Earth Asteroid 2024 BX1. Characterization of near-Earth objects (NEOs) is critical for Earth-impact hazard assessment. Particularly crucial to our physical understanding of NEOs are laboratory spectral measurements of meteorites as they are the best and most widely available analog materials, barring sample return missions. However, most meteorites do not have direct orbital links to specific asteroids, making it challenging to identify their source body in the NEO or main-belt asteroid populations. Near-Earth asteroid (NEA) 2024 BX1 was discovered on 2024 January 20 at 21:48 UTC from MPC code K88, impacting the Earth (west of Berlin, Germany) 165 minutes later. The incoming bolide was observed by multiple meteor cameras, which enabled successful reconstruction of its exo-atmospheric orbit and quick recovery. We present results from laboratory spectral characterization of the Ribbeck meteorite in the UV–mid-infrared wavelengths (0.2–14.2 μm) over seven grain size bins (&lt;45 μm–slab). Our results suggest that Ribbeck has spectral properties consistent with enstatite achondrite (aubrite) meteorites. Our grain-size spectral analysis shows that albedo and spectral slope decrease as grain size increases. In addition, increasing grain size also shifts the taxonomic type in the Bus–DeMeo system from Xn to B types, suggesting the limitations of taxonomy in classifying small, regolith-free NEAs. We also present results of our comparison between Ribbeck data and spectra of E types in the main-belt and NEA populations. Principal component analysis of our Ribbeck samples shows variations parallel to the α line, which can be confused with space weathering in PC space.

Keywords: Near-Earth objects, Small Solar System bodies, Infrared spectroscopy, Ultraviolet spectroscopy, Spectroscopy, Meteorites, Near infrared astronomy
Discovery and Classification in Astronomy: Scientific and Philosophical Challenges and the Importance of a Comprehensive and Consistent Classification System. Throughout history, the definition of "class" and the construction of astronomical classification systems has been a deep scientific and philosophical problem: scientific because facts such as physical composition ideally need to be known for proper classification but often are not, philosophical because astronomers need to understand the philosophical assumptions behind their attempts at classification, and because different philosophical ideas such as "natural kinds" often guide classification, even if unconsciously. The primary lesson of history is that the most useful classifications of celestial objects are optimally based on their physical nature. The second lesson is that because discovery is an extended process consisting of detection, interpretation, and understanding, initial classifications may be phenomenological, based on characteristics that may be useful in early "detection" stages of extended discovery. By contrast, final classifications of "the thing itself," is achieved only after the "understanding" stage of discovery and must have a physical basis. A third lesson is that class status is best determined within a comprehensive classification system in order to determine taxon level, e.g., class, type, subtype. Such a system, encompassing all astronomical objects, illustrates the problems of class and classification, problems that may be applied to exoplanet discoveries.

Keywords: Classification systems, Solar system planets, Morgan-Keenan classification, Galaxy classification systems, Henry Draper catalog, Exoplanet astronomy, Stellar classification, De Vaucouleurs Sandage classification, Dwarf planets, Nebulae
Interpolation and Synthesis of Sparse Samples in Exoplanet Atmospheric Modeling. This paper highlights methods from geostatistics that are relevant to the interpretation, intercomparison, and synthesis of atmospheric model data, with a specific application to exoplanet atmospheric modeling. Climate models are increasingly used to study theoretical and observational properties of exoplanets, which include a hierarchy of models ranging from fast and idealized models to those that are slower but more comprehensive. Exploring large parameter spaces with computationally expensive models can be accomplished with sparse sampling techniques, but analyzing such sparse samples can pose challenges for conventional interpolation functions. Ordinary kriging is a statistical method for describing the spatial distribution of a data set in terms of the variogram function, which can be used to interpolate sparse samples across any number of dimensions. Variograms themselves may also be useful diagnostic tools for describing the spatial distribution of model data in exoplanet atmospheric model intercomparison projects. Universal kriging is another method that can synthesize data calculated by models of different complexity, which can be used to combine sparse samples of data from slow models with larger samples of data from fast models. Ordinary and universal kriging can also provide a way to synthesize model predictions with sparse samples of exoplanet observations and may have other applications in exoplanet science.

Keywords: Exoplanet astronomy, Importance sampling, Planetary climates
2023 DZ2 Planetary Defense Campaign. We present the results of a fourth planetary defense exercise, focused this time on the small near-Earth asteroid (NEA) 2023 DZ2 and conducted during its close approach to the Earth in 2023 March. The International Asteroid Warning Network (IAWN), with support from NASA's Planetary Defense Coordination Office (PDCO), has been coordinating planetary defense observational campaigns since 2017 to test the operational readiness of the global planetary defense capabilities. The last campaign focused on the NEA Apophis, and an outcome of that exercise was the need for a short burst campaign to replicate a real-life near-Earth object impact hazard scenario. The goal of the 2023 DZ2 campaign was to characterize the small NEA as a potential impactor and exercise the planetary defense system including observations, hypothetical risk assessment and risk prediction, and hazard communication with a short notice of just 24 hr. The entire campaign lasted about 10 days. The campaign team was divided into several working groups based on the characterization method: photometry, spectroscopy, thermal IR photometry and optical polarimetry, radar, and risk assessment. Science results from the campaign show that 2023 DZ2 has a rotation period of 6.2745 ± 0.0030 minutes; visible wavelength color photometry/spectroscopy/polarimetry and near-IR spectroscopy all point to an E-type taxonomic classification with surface composition analogous to aubrite meteorites; and radar observations show that the object has a diameter of 30 ± 10 m, consistent with the high albedo (0.49) derived from polarimetric and thermal IR observations.

Keywords: Near-Earth objects, Small Solar System bodies, Asteroids, Achondrites, Close encounters
Tidal Seismicity in the Moon and Implications for the Rocky Interior of Europa. Seismology is a powerful tool for probing the deep interiors of planetary bodies. Just as deep moonquakes triggered by Earth's tides occur on the Moon, as observed by the Apollo seismometers, icy moons of the giant planets may also have seismically active deep interiors, opening up future prospects for in situ seismic investigations at their surfaces. Of notable interest is Jupiter's moon Europa, with its dynamic ice shell and potentially habitable subsurface ocean. In this work, we use different interior models of the Moon and model the tidal stress inside them to determine the most likely times and locations for the triggering of tidal moonquakes. Using the Mohr–Coulomb failure criterion, we derive cohesion and friction values for the lunar interior to match the observations of deep moonquakes by Apollo at a depth between 700 and 1200 km. By extending the same approach to different interior models of Europa, we show that Europa quakes triggered by the tides of Jupiter are 10 times more likely to occur than tidal moonquakes. The strength and depth of these tidal Europa quakes (euroquakes) strongly depend on the interior structure, with stronger events at the core–mantle boundary for liquid core models, while solid core models can be more prone to failure at the bottom of the ocean floor. Models without a metallic core favor failure in the upper third of the mantle with event strength similar to that in the solid core models.

Keywords: Ocean planets, Natural satellite dynamics, Lunar seismology, Europa, Galilean satellites
Detection of Close Kuiper Belt Binaries with HST WFC3. Binaries in the Kuiper Belt are common. Here we present our analysis of the Solar System Origins Legacy Survey (SSOLS) to show that using a point-spread function (PSF)-fitting method can roughly double the number of binaries identified in that data set. Out of 198 Kuiper Belt objects (KBOs) observed by SSOLS, we find 23 to be visually separated binaries, while a further 19 are blended PSF binaries detectable with the method we present here. This is an overall binary fraction of 21% for the SSOLS data set of cold classical KBOs. In addition, we tested our fitting methods on synthetic data, and while we were able to show them to be very effective at detecting certain blended-PSF binary KBOs, fainter or closer binary KBOs may easily be missed, suggesting that the close binary KBO fraction could be even higher. These results strongly support the idea that most (if not all) KBOs were formed through the streaming instability process, and as a consequence, most KBOs were formed as near-equal mass binaries.

Keywords: Asteroid satellites, Classical Kuiper belt objects, Trans-Neptunian objects
Constraining Time Variations in Enceladus's Water-vapor Plume with Near-infrared Spectra from Cassini's Visual and Infrared Mapping Spectrometer. Water vapor produces a series of diagnostic emission lines in the near-infrared between 2.60 and 2.75 μm. The Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft detected this emission signal from Enceladus's plume, and so VIMS observations provide information about the variability of the plume's water-vapor content. Using a data set of 249 spectral cubes with relatively high signal-to-noise ratios, we confirmed the strength of this water-vapor emission feature corresponds to a line-of-sight column density of order 1020 molecules m‑2, which is consistent with previous measurements from Cassini's Ultraviolet Imaging Spectrograph. Comparing observations made at different times indicates that the water-vapor flux is unlikely to vary systematically with Enceladus's orbital phase, unlike the particle flux, which does vary with orbital phase. However, variations in the column density on longer and shorter timescales cannot be ruled out and merit further investigation.

Keywords: Water vapor, Infrared spectroscopy, Enceladus, Saturnian satellites, Volcanism
The Limited Role of the Streaming Instability during Moon and Exomoon Formation. It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (≫100 km) form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly. This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vapor-poor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the previous suggestion that small planets (&lt;1.6 R ⊕) are good candidates to host large moons because their impact-induced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an impact-induced disk, whereas it plays a key role during planet formation.

Keywords: Earth-moon system
Energy and Temperature Dependencies for Electron-induced Sputtering from H<SUB>2</SUB>O Ice: Implications for the Icy Galilean Moons. To better assess the role that electrons play in exosphere production on icy bodies, we measured the total and O2 sputtering yields from H2O ice for electrons with energies between 0.75 and 10 keV and temperatures between 15 and 124.5 K. We find that both total and O2 yields increase with decreasing energy over our studied range, that they increase rapidly at temperatures above 60 K, and that the relative amount of H2O in the sputtered flux decreases quickly with increasing energy. Combining our data with other electron data in the literature, we show that the accuracy of a widely used sputtering model can be improved significantly for electrons by adjusting some of the intrinsic parameter values. Applying our results to Europa, we estimate that the contribution of electrons to the production of the O2 exosphere is equal to the combined contribution of all ions. In contrast, sputtering of O2 from Ganymede and Callisto appears to be dominated by irradiating ions, though electrons still likely contribute a nonnegligible amount. While our estimates could be further refined by examining the importance of spatial variations in electron flux, we conclude that, at the very least, electrons seem to be important for exosphere production on icy surfaces and should be included in future modeling efforts.

Keywords: Ganymede, Callisto, Experimental data, Surface processes, Ice physics, Laboratory astrophysics, Radiation interactions (Ice), Europa, Astrochemistry, Surface ices, Markov chain Monte Carlo, Galilean satellites
Geologic History of the Amundsen Crater Region Near the Lunar South Pole: Basis for Future Exploration. We provide the first detailed 1:100,000 scale geomorphologic map of the ∼100 km Amundsen crater region, which is of high scientific relevance for future exploration, e.g., NASA's VIPER mission, the Artemis program, and the Chinese International Lunar Research Station. We investigated the complex geological history of the region before and after the formation of Amundsen crater on the rims of the South Pole–Aitken (SPA) and Amundsen–Ganswindt basins. We present a new Amundsen crater formation age of ∼4.04 Ga, which, in contrast to previously derived ages, is based on non-light-plains terrain. The estimated maximum excavation depth for Amundsen crater is ∼8 km, and elevated concentrations of FeO near the crater suggest that Amundsen may have redistributed SPA-derived materials. Plains materials of various kinds were observed both inside and outside Amundsen crater and are estimated to be up to 350 m thick and ∼3.8 Ga old. A less cratered, tens of meters thick mantling unit indicates a resurfacing event ∼3.7 Ga ago. We highlight five potential exploration sites that satisfy technical constraints (such as shallow slopes, solar illumination, and Earth visibility), provide materials that can be sampled, and are capable of addressing multiple science objectives. Due to its accessibility and traversability, combined with its geologic diversity, proximity of permanently shadowed regions for studying volatile processes, and ability to address multiple science objectives, we confirm and reinforce the Amundsen crater region as a high-priority landing and exploration site.

Keywords: Lunar craters, Planetary surfaces, Planetary polar regions, The Moon, Planetary mineralogy, Lunar science, Lunar geochronology, Lunar surface, Planetary geology
Retrieved Atmospheres and Inferred Surface Properties for Terrestrial Exoplanets Using Transmission and Reflected-light Spectroscopy. Future astrophysics missions will seek extraterrestrial life via transmission and direct-imaging observations. To assess habitability and biosignatures, we need robust retrieval tools to analyze observed spectra, and infer surface and atmospheric properties with their uncertainties. We use a novel retrieval tool to assess accuracy in characterizing near-surface habitability and biosignatures via simulated transmission and direct-imaging spectra, based on the Origins Space Telescope (Origins) and LUVOIR mission concepts. We assess our ability to discriminate between an Earth-like and a false-positive O3 TRAPPIST-1 e with transmission spectroscopy. In reflected light, we assess the robustness of retrieval results to unmodeled cloud extinction. We find that assessing habitability using transmission spectra may be challenging due to relative insensitivity to surface temperature and near-surface H2O abundances. Nonetheless, our order-of-magnitude H2O constraints can discriminate extremely desiccated worlds. Direct imaging is insensitive to surface temperature and subject to the radius/albedo degeneracy, but this method proves highly sensitive to surface water abundance, achieving retrieval precision within 0.1% even with partial clouds. Concerning biosignatures, Origins-like transmission observations (t = 40 hr) may detect the CO2/CH4 pair on M-dwarf planets and differentiate between biological and false-positive O3 using H2O and abundant CO. In contrast, direct-imaging observations with LUVOIR-A (t = 10 hr) are better suited to constraining O2 and O3, and may be sensitive to wavelength-dependent water cloud features, but will struggle to detect modern-Earth-like abundances of methane. For direct imaging, we weakly detect a stratospheric ozone bulge by fitting the near-UV wings of the Hartley band.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric composition , Exoplanets, Planetary atmospheres, Astrobiology, Biosignatures, Habitable planets, Exoplanet atmospheres, Exoplanet atmospheric structure