Sazuna/UAT_keywords huggingface dataset:
Detecting Extraterrestrial Civilizations that Employ an Earth-level Deep Space Network. A major aspect of the search for extraterrestrial intelligence (SETI) involves searching for electromagnetic transmissions from extraterrestrial sources, often using our own transmissions as a guide. Previous studies have suggested that humanity's most consistently detectable technosignatures were transmissions from our deep-space networks and interplanetary radar. In this study, we analyze NASA Deep Space Network logs to explore what strategies for selecting SETI targets and scheduling observations would enhance the chances of detecting such networks. Analyzing Deep Space Network uplink transmission logs over the last 20 yr, we find that these emissions were predominantly directed along the ecliptic plane, toward or directly away from the Sun, and toward other planets. The average duty cycle within the Earth Transit Zone is 20 times higher than that across all ecliptic latitudes. In the case of Mars, we find a species that is able to observe the solar system for radio emission during an Earth-Mars conjunction in the past 20 yr would have had a 77% chance of observing during one of our transmissions, a 4 × 105-fold increase over intercepting our Deep Space Network transmission versus a random observer at a random time. These findings quantify how SETI searches might benefit from prioritizing edge-on exoplanet systems and aligning observation windows with exoplanetary conjunctions or planet─planet occultations because they significantly improve the likelihood of intercepting transmissions from any civilizations employing deep-space networks similar to our own.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Astrobiology, Radio astronomy
Hubble Space Telescope Observations of the Interstellar Interloper 3I/ATLAS. We present high-angular-resolution observations of the third known interstellar interloper, 3I/ATLAS, from the Hubble Space Telescope. The object is clearly active at 3.8 au preperihelion, showing dust emitted from the hot, Sun-facing side of the nucleus and a weak, radiation-pressure-swept tail away from the Sun. We apply a simple model to estimate the mass loss rate in dust as dM/dt ∼ 12  aμ1/2  kg s−1, where aμ is the mean particle size in microns. With 1 ≤ aμ ≤ 100, we infer dM/dt ∼ 12─120 kg s−1. A fit to the surface brightness distribution of the inner coma limits the effective radius of the nucleus to rn ≤ 2.8 km, assuming red geometric albedo 0.04. Conversely, the nucleus cannot be smaller than ∼0.22 km in radius if its coma is supplied by sublimation of carbon monoxide and must be larger if a less volatile molecule drives the mass loss.

Keywords: Comet tails, Comet nuclei, Interstellar objects, Comets, Comet origins
Unveiling Unprecedented Fine Structure in Coronal Flare Loops with the DKIST. We present the highest-resolution Hα observations of a solar flare to date, collected during the decay phase of an X1.3-class flare on 2024 August 8 at 20:12 UT. Observations with the Visible Broadband Imager at the National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST) reveal dark coronal loop strands at unprecedented spatial resolution in the flare arcade above highly structured chromospheric flare ribbons. After surveying the 20 best-seeing images, we calculate a mean loop width near the top of the arcade of 48.2 km, with a minimum loop width of ∼21 km and distribution mode of ∼43 km. The distributions of loop widths observed by the DKIST in our study are often symmetric about the mean loop width. This is initial evidence that the DKIST may be capable of resolving the fundamental scale of coronal loops, although further investigation is required to confirm this result. We demonstrate that the resolving power of the DKIST represents a significant step toward advancing modern flare models and our understanding of fine structure in the coronal magnetic field.

Keywords: Solar flares, Solar coronal loops, Solar active regions, Solar corona, Solar x-ray flares
Observational Evidence for the Modulation of Magnetopause Position by Solar Wind Turbulence. It has long been known that magnetopause position is primarily controlled by the solar wind dynamic pressure and the interplanetary magnetic field. This classical view, however, largely overlooks the ubiquitous role of solar wind turbulence. Consequently, it remains unclear which turbulent properties most effectively modulate the magnetopause position, on what characteristic scales these effects are most pronounced, and how these turbulence-driven effects are physically mediated. Employing a quasi-controlled-variable approach and excluding dominant disturbances, we perform the first direct statistical investigation by selecting 45 magnetopause crossing events (from 38,018 total between 2007 and 2022) under nearly identical background conditions, isolating the effects of turbulence characterized by its spectral properties, partial variance of increments, and the local energy transfer rate. The analysis, further validated by Cohen's d effect sizes, reveals that turbulence could modulate the magnetopause position: intervals with flatter plasma spectra in the inertial range, higher incidence of intermittent structures (particularly at ∼47 s), and more intense energy transfer rates (particularly at ∼6 minutes) correlate with a more distant, outward-shifted boundary. These results tend to suggest that highly turbulent solar wind could enhance energy and momentum transfer into the magnetosphere, likely via a combination of viscous-like interactions, localized heating at intermittent structures, and resonant Alfvénic fluctuations, causing the outer magnetosphere to heat and expand. This work provides the first observational quantification of this fundamental coupling, which may offer crucial benchmarks for numerical simulations and new avenues for theoretical research.

Keywords: Interplanetary turbulence, Planetary magnetospheres, Solar wind, Solar-planetary interactions
Hidden Activity Revealed: Photospheric Energetics and Dynamics with High-resolution Magnetographic Data. We revisit an existing but unexplored finding on the calculation of the baseline (i.e., potential) magnetic energy in observed solar magnetic configurations and apply it to two series of high-cadence, cospatial, and cotemporal line-of-sight photospheric magnetograms with a factor of ∼4 difference in spatial resolution. The target is a small coronal hole, ∼80″ across. We find significant differences between the two data sets, with approximate factors of 2.4 in the unsigned magnetic flux, 2.1 in the potential magnetic energy, and 5.2 in the mean amplitudes of the energy variation, all in favor of the higher-resolution magnetograms. Additionally, we find a factor of 2.5 difference in the characteristic magnetic flux replenishment time, with configurations at higher resolution renewing their flux every 46 minutes on average. Energy decreases associated with apparent magnetic flux cancellation events in higher resolution yield power densities above 106 erg cm‑2 s‑1, seemingly sufficient to sustain coronal holes and drive the fast solar wind. For the first time, this represents apparent energy released at photospheric altitudes rather than energy deposited via the Poynting flux. Lower-resolution magnetograms give 5.4 times less power density output. These intriguing results could have wide-ranging implications for in situ solar wind measurements and their solar sources in the Parker Solar Probe mission, as well as for high-resolution observations featuring simultaneous photospheric and chromospheric magnetograms including, but not limited to, data from the Daniel K. Inouye Solar Telescope.

Keywords: Quiet sun, Solar magnetic flux emergence, Solar photosphere, Solar magnetic reconnection
Black Hole Survival Guide: Searching for Stars in the Galactic Center that Endure Partial Tidal Disruption. Once per ≍104─105 yr, an unlucky star may experience a close encounter with a supermassive black hole (SMBH), partially or fully tearing apart the star in an exceedingly brief, bright interaction called a tidal disruption event (TDE). Remnants of partial TDEs are expected to be plentiful in our Galactic center, where at least six unexplained, diffuse, star-like "G objects" have already been detected, which may have formed via interactions between stars and the SMBH. Using numerical simulations, this work aims to identify the characteristics of TDE remnants. We take 3D hydrodynamic FLASH models of partially disrupted stars and map them into the 1D stellar evolution code MESA to examine the properties of these remnants from tens to billions of years after the TDE. The remnants initially exhibit a brief, highly luminous phase, followed by an extended cooling period as they return to stable hydrogen burning. During the initial stage (≲105 yr) their luminosities increase by orders of magnitude, making them intriguing candidates to explain a fraction of the mysterious G objects. Notably, mild TDEs are the most common, and result in the brightest remnants during this initial phase. However, most remnants exist in a long-lived stage where they are only modestly offset in temperature and luminosity compared to main-sequence stars of equivalent mass. Nonetheless, our results indicate remnants will sustain abnormal, metal-enriched envelopes that may be discernible through spectroscopic analysis. Identifying TDE survivors within the Milky Way could further illuminate some of the most gravitationally intense encounters in the Universe.

Keywords: Galactic center, High energy astrophysics, Tidal disruption, Astronomical simulations, Stellar evolution
WIde Separation Planets In Time (WISPIT): A Gap-clearing Planet in a Multi-ringed Disk around the Young Solar-type Star WISPIT 2. In the past decades, several thousand exoplanet systems have been discovered around evolved, main-sequence stars, revealing a wide diversity in their architectures. To understand how the planet formation process can lead to vastly different outcomes in system architecture, we have to study the starting conditions of planet formation within the disks around young stars. In this study, we are presenting high-resolution direct imaging observations with the Very Large Telescope/SPHERE of the young (∼5 Myr), nearby (∼133 pc), solar-analog designated as WISPIT 2 (= TYC 5709-354-1). These observations were taken as part of our survey program that explores the formation and orbital evolution of wide-separation gas giants. WISPIT 2 was observed in four independent epochs using polarized light and total intensity observations. They reveal for the first time an extended (380 au) disk in scattered light with a multi-ringed substructure. We directly detect a young protoplanet, WISPIT 2b, embedded in a disk gap and show that it is comoving with its host star. Multiple SPHERE epochs demonstrate that it shows orbital motion consistent with Keplerian motion in the observed disk gap. Our H- and Ks-band photometric data are consistent with thermal emission from a young planet. By comparison with planet evolutionary models, we find a mass of the planet of  4.9−0.6+0.9 MJup. This mass is also consistent with the width of the observed disk gap, retrieved from hydrodynamic models. WISPIT 2b is the first unambiguous planet detection in a multi-ringed disk, making the WISPIT 2 system the ideal laboratory to study planet─disk interaction and subsequent evolution.

Keywords: Exoplanets, Direct imaging, Circumstellar disks, Exoplanet formation, Polarimetry
Wide Separation Planets in Time (WISPIT): Discovery of a Gap Hα Protoplanet WISPIT 2b with MagAO-X. Excellent (&lt;25 mas) Hα images of the star TYC 5709-354-1 led to the discovery of a rare Hα protoplanet. This star was discovered by the WISPIT survey to have a large multi-ring transitional disk, and is hereafter WISPIT 2. Our Hα images of 2025 April 13 and 16 discovered an accreting (Hα in emission) protoplanet: WISPIT 2b (r = 309.43 ± 1.56 mas; (∼54 au deprojected), PA = 242 .° 21 ± 0 .° 41) likely clearing a dust-free gap between the two brightest dust rings in the transitional disk. Our signal-to-noise ratio of 12.5 detection gave an Hα ASDI contrast of (6.5 ± 0.5) × 10‑4 and an Hα line flux of (1.29 ± 0.28) × 10‑15 erg s‑1 cm‑2. We also present L' photometry from LBT/LMIRcam of the planet (L' = 15.30 ± 0.05 mag), which, when coupled with an age of  5.1‑1.3+2.4  Myr, yields a planet mass estimate of 5.3 ± 1.0 Mjup from the DUSTY evolutionary models. WISPIT 2b is accreting at  2.25‑0.17+3.75  × 10‑12 MSun yr‑1. WISPIT 2b is very similar to the other Hα protoplanets in terms of mass, age, flux, and accretion rate. The inclination of the system (i = 44°) is also, surprisingly, very similar to the other known Hα protoplanet systems, which all cluster from 37° ≤ i ≤ 52°. We argue this clustering has only a ∼1.0% (2.6σ) probability of occurring randomly, and so we speculate that magnetospherical accretion might have a preferred inclination range (∼37°–52°) for the direct (cloud free, low extinction) line of sight to the Hα line formation/shock region. We also find at 110 mas (∼15 au deprojected) a close companion candidate (CC1) that may be consistent with an inner dusty 9 ± 4 Mjup planet.

Keywords: Accretion, Exoplanet atmospheres, Adaptive optics, Exoplanet astronomy, T Tauri stars, Protoplanetary disks, Exoplanet formation, Planet formation
exoALMA. XVIII. Interpreting Large-scale Kinematic Structures as Moderate Warping. The exoALMA program gave an unprecedented view of the complex kinematics of protoplanetary disks, revealing diverse structures that remain poorly understood. We show that moderate disk warps (∼0 .° 5─2°) can naturally explain many of the observed large-scale velocity features with azimuthal wavenumber m = 1. Using a simple model, we interpret line-of-sight velocity variations as changes in the projected Keplerian rotation caused by warping of the disk. While not a unique explanation, this interpretation aligns with growing observational evidence that warps are common. We demonstrate that such warps can also produce spiral structures in scattered light and CO brightness temperature, with ∼10 K variations in MWC 758. Within the exoALMA sample, warp properties correlate with stellar accretion rates, suggesting a link between the inner disk and outer disk kinematics. If warps cause large-scale kinematic structure, this has far-reaching implications for turbulence, angular momentum transport, and planet formation.

Keywords: Pre-main sequence stars, Astronomy data analysis, Protoplanetary disks, Hydrodynamics
A Constraint on the Density of Jupiter's Moon Thebe from Primordial Dynamics. Of the 97 known satellites in the Jovian system, the individual masses and densities of each moon have only been determined for six of them: the four Galileans, Amalthea, and Himalia. In this Letter, we derive a prediction for the mean density (and mass) of Thebe, Jupiter's sixth-largest regular moon, obtaining a lower limit of ρT ≳ 1.0 g cm–3 (mT ≳ 5 × 1020 g). In particular, this value emerges as a key constraint within the context of the resonant transport model for the origins of Jupiter's interior satellites. Expanding on this theory, here we carry out simulations of the simultaneous gravitational shepherding of Amalthea and Thebe via the resonant influence of inward-migrating Io during Jupiter's disk-bearing epoch. We find that owing to overstability of resonant dynamics facilitated by the circumjovian disk's aerodynamic drag, Thebe's smaller radius (compared to that of Amalthea) requires a higher density to ensure its terminal orbital distance exceeds that of Amalthea, as it does today. With multiple current and upcoming space missions devoted to in situ exploration of the Jovian system, a proper measurement of Thebe's mass provides an avenue toward empirical falsification or confirmation of our theoretical model for the dynamical evolution of Jupiter's inner moons.

Keywords: Natural satellite dynamics, Natural satellites (Solar system), Solar system gas giant planets, Planetary dynamics, Jovian satellites
Li Enrichment in Red Clump Giants: Clues for Past Binary Interaction or Merger Events. To understand the underlying mechanisms of high Li abundances among core He-burning or red clump (RC) giants, we analyzed a sample of 5227 RC giants of mass M ≤ 2 M⊙ using spectra and asteroseismic data. We found 120 RC giants (∼2%) with a lower limit of A(Li) = 0.7 dex, a factor of 40 more than their predecessors close to the red giant branch tip. Of the 120 RC giants, we could measure actual rotations for 16 RC giants using stellar spots from the Kepler light-curve analysis. We found that most of the high-rotation RC giants are also very high Li-rich RC giants, and the rotation seems to decline rapidly with Li abundance depletion, suggesting that both the high rotation and high Li abundance are transient phenomena and associated with a single source. Further, we found a significantly high occurrence of 15% and 12% of Li-rich RC giants among extremely low-mass RC giants and RC giants with anomalous [C/N] ratios, respectively. The extremely low mass, fast rotation, and anomalous [C/N] values of RC giants are attributed to their past binary interaction/merger history. The results pose the question of whether the binary interaction/merger is a prerequisite, along with the He flash, for Li enhancement among RC giants.

Keywords: Stellar mergers, Chemical abundances, Stellar mass loss, Helium burning, Stellar rotation
Signature of a Dark Ultracompact Dwarf Galaxy Transiting the Milky Way Disk. We report the discovery of a vertical velocity anomaly in the stellar component of the Galactic disk, consistent with the impact of a dark, ultracompact dwarf galaxy (UCD)-sized object plunging into the Milky Way. The anomaly spatially coincides with a suite of gaseous disturbances—including an H I void, a molecular shell (CO 16.134–0.553), and a vertical H I filament—previously interpreted as signatures of a dark matter subhalo (DMSH) collision. Analysis of Gaia DR2 astrometry reveals a statistically significant vertical velocity dip colocated with these features, supporting a dynamical origin. The absence of a luminous source at the filament's terminus suggests a dark or failed UCD. These results provide rare observational evidence for a low-mass DMSH, with implications for the substructure of dark matter halos and constraints on the ΛCDM model.

Keywords: Milky Way dark matter halo
The Kinematic Age of 3I/ATLAS and Its Implications for Early Planet Formation. The recent discovery of the third interstellar object (3I/ATLAS) expands the known census from two to three and significantly improves statistical inferences regarding the underlying Galactic population. In this Letter, we argue that cometary activity likely significantly contributes to 3I/ATLAS's brightness since the nuclear size inferred when assuming an asteroidal reflectance implies an untenable interstellar object mass per star. Relative to the Sun, 3I/ATLAS exhibits a high excess velocity of v∞ = 58 km s‑1, which implies that 3I/ATLAS is relatively old in comparison to previous interstellar objects. Here, we calculate the posterior distribution of ages implied by the kinematics of the interstellar objects and find that 3I/ATLAS is likely ∼3–11 Gyr old, assuming that the interstellar object and stellar age–velocity dispersion relations are equivalent. We also calculate the distribution of host star metallicities and find that 3I/ATLAS has a 12% chance of originating from a star with [Fe/H] ≤ ‑0.4. These results show that interstellar object formation is likely efficient at low metallicities and early in the history of the Galaxy. Finally, we estimate the interstellar object formation rate throughout Galactic history implied by these three objects. As future interstellar objects are discovered, the framework presented here can be applied to further refine this calculation. Comparison between the interstellar object and stellar formation histories will provide unique insights into the history of stellar system formation in the Galaxy.

Keywords: Small Solar System bodies, Comets, Asteroids, Interstellar objects
Milky Way's Metal-poor Stars Display Chemical Transition near the Solar Radius. The metal-poor stars of a galaxy offer insights into that galaxy's early formation processes and accretion history. Here, we investigate whether the metal-poor stars of our Milky Way Galaxy exhibit any characteristic trends in Galactocentric distance versus chemical abundances—i.e., in the space of rGC versus [Fe/H] and rGC versus [X/Fe]—and if yes, then what their implication is for Galaxy formation. We combine the data sets of APOGEE DR17 and Gaia DR3, where the former provides stellar abundances and the latter provides stellar parallaxes. We analyze bright (G &lt; 13) and metal-poor ([Fe/H] &lt; ‑1.2) stars located far from the disk (∣z∣ ≥ 1 kpc) and explore a total of 19 abundances. We find that nine different abundances exhibit a drastic transition in their distribution near the solar radius rGC = 8 kpc. This trend is very unlikely to be related to radial migration, as our metal-poor sample does not contain any disk star. We also analyze the Gaia-Sausage/Enceladus stars, which form a dominant metal-poor population of the Galaxy, and find that they alone cannot account for this trend. This suggests that the Milky Way's metal-poor populations inside and outside the solar radius likely originated from distinct chemical enrichment scenarios and formation processes.

Keywords: Surveys, Galaxy abundances, Milky Way formation
From Photospheric Footpoint Motion to Plasmoid Ejection: A Two-stage Reconnection Process in a Small-scale Chromospheric Jet. Using high-spatiotemporal-resolution multiwavelength observations from the New Vacuum Solar Telescope and the Solar Dynamics Observatory, we present a detailed analysis of a small-scale chromospheric jet driven by plasmoid-mediated magnetic reconnection. Our results reveal that the entire process is governed by the dynamic evolution of photospheric magnetic footpoints, which proceeds in two distinct stages. An initial separating motion of the footpoints corresponds to a mild reconnection phase, characterized by a short current sheet and the eruption of a cool Hα jet. Subsequently, a converging motion of the footpoints triggers an intense reconnection phase. During this intense stage, the current sheet rapidly elongates, and the resulting decrease in its aspect ratio initiates a tearing-mode instability, forming a plasmoid. The appearance of this plasmoid mediates the onset of fast magnetic reconnection, which produces a hot extreme ultraviolet jet and is concurrent with significant magnetic flux cancellation. We interpret this cancellation as the submergence of newly formed postreconnection loops. Furthermore, we identify a distinct, high-temperature plasma blob in the jet spire, significantly hotter than the surrounding jet plasma. We attribute this feature to a secondary heating process, likely caused by reconnection between the upward-propagating plasmoid and the overlying magnetic cusp structure. These observations provide a comprehensive, observationally driven picture (from the initial photospheric triggers to the multistage plasmoid-mediated reconnection) that forms chromospheric jets, highlighting the critical role of footpoint motions in solar atmospheric dynamics.

Keywords: Solar magnetic fields, Magnetohydrodynamics, Solar chromosphere, Solar magnetic reconnection