Sazuna/UAT_keywords huggingface dataset:
Astrometry with Interplanetary Spacecraft: Determination of the Non-gravitational Accelerations of the Interstellar Object 3I/ATLAS. Here, we report on the results of adding 6 observations from 2 interplanetary spacecraft to the orbit determination of 3I/ATLAS, the third known Interstellar Object. These observations, from vantage points and times impossible with terrestrial instruments, reduce the formal errors on the non-gravitational acceleration (NGA) parameters formal errors by 20%─40% compared to solutions using just the terrestrial data available from 2025 May to December. Using these data we find significant NGAs in the 3I/ATLAS trajectory, with a vector magnitude scaled to 1 au of (89.3 ± 4.6) × 10−9 au day−2, and a time offset (∆T) of −34.60 ± 2.62 days (i.e., an acceleration peaking ∼one month before perihelion). This leads to a rough mass estimate for 3I/ATLAS of 44 million tons in early 2025 August, equivalent to a CO2 dominated nucleus radius rn ≲ 374 m.

Keywords: Exocomets, Comet dynamics, Interstellar objects
An SMA Survey of UV-driven Chemical Tracers in Transition Disks. The chemistry of protoplanetary disks is influenced by stellar irradiation and dust evolution, both of which shape the physical conditions governing planet formation. In particular, molecules such as HCO+ and CN trace ionization and photochemistry in surface layers exposed to UV radiation. Here, we present Submillimeter Array observations of HCO+ J = 3─2, 4─3 and CN N = 3─2 in five transition disks (V4046 Sgr, GM Aur, J1604, GG Tau, LkCa 15) with large dust cavities to assess how disk structure influences the observed emission. When combined with literature data, we identify a tentative trend of increasing line fluxes with cavity size, suggesting that reduced dust opacities in larger cavities enhance UV penetration and stimulate ion-radical chemistry. These results support a scenario in which disk structure modulates chemistry and highlights the potential of HCO+ and CN as tracers of UV-driven processes.

Keywords: Protoplanetary disks, Planet formation, Astrochemistry
JWST/NIRCam: Stellar Extinction Reveals the CND of NGC 1068. I present a new view of the circumnuclear disk (CND) of NGC 1068 based on stellar─continuum extinction measured on a JWST/NIRCam image at 1.5 μm. After estimating the underlying stellar background, I derive a two-dimensional extinction map around the nucleus tracing the cold dust distribution. Comparing it with a CO(2─1) emission map obtained with Atacama Large Millimeter/submillimeter Array reveals a remarkable correspondence with the molecular gas distribution, from the global ∼400 pc ring and its ∼130 pc cavity down to the smallest resolved structures. I nevertheless identify large scale relative differences in amplitude, that may indicate that the CND is inclined with respect to the stellar disk. These results demonstrate the potential of JWST to trace molecular structures around active galactic nucleus in the absence of millimetric observations.

Keywords: AGN host galaxies, Active galactic nuclei, Interstellar dust extinction, Near infrared astronomy
Investigating Low-frequency Radio Variability of BAT AGN with VLITE. Active Galactic Nuclei (AGN) variability in the low-frequency radio range is a relatively unexplored phenomenon. Here, we investigated the Very Large Array Low-band Ionosphere and Transient Experiment observations at 352 MHz of objects in the BAT AGN catalog. We found variability in 31 of the 32 objects in the sample with 5 or more data points and performed a number of tests to rule out the possibility that this variability was due to interstellar scintillation. We determined that the ensemble variability was likely to be intrinsic, a result that emphasizes the need for directed observations of these objects in the low-frequency radio range in the future.

Keywords: Radio active galactic nuclei, Active galactic nuclei, Time domain astronomy
Evidence for No Orbital Decay in the Hot Jupiter XO-3b from Transit-timing Analysis. The exoplanet XO-3b has been proposed by multiple works as a potential candidate for transit time variations and orbital decay. This work uses data from the Transiting Exoplanet Survey Satellite, the Exoplanet Transit Database, the ExoClock project, and previous literature to analyze the transit times of XO-3b to conclude that there is no statistically significant evidence for orbital decay in the planet XO-3b, contrary to previous literature. However, an underestimation of the errors of the transit times used can undermine the validity of the model. Further transit observation of this and other exoplanets is suggested.

Keywords: Exoplanet astronomy, Hot Jupiters, Transit timing variation method, Exoplanets
The Eschatian Hypothesis. The history of astronomical discovery shows that many of the most detectable phenomena, especially detection firsts, are not typical members of their broader class, but rather rare, extreme cases with disproportionately large observational signatures. Motivated by this, we propose the Eschatian Hypothesis: that the first confirmed detection of an extraterrestrial technological civilization is most likely to be an atypical example, one that is unusually "loud" (i.e., producing an anomalously strong technosignature), and plausibly in a transitory, unstable, or even terminal phase. Using a toy model, we derive conditions under which such loud civilizations dominate detections, finding for example that if a society is loud for only 10−6 of its lifetime, it must emit ≳1% of its total observable energy budget during that phase to outrun quieter populations. The hypothesis naturally motivates agnostic anomaly searches in wide-field, multi-channel, continuous surveys as a practical strategy for a first detection of extraterrestrial technology.

Keywords: Observational astronomy, Search for extraterrestrial intelligence, Technosignatures
Is the Anti-tail of 3I/ATLAS Composed of Macroscopic Non-volatile Objects?. I suggest that the teardrop shape of the coma in post-perihelion images of 3I/ATLAS is a result of a large number of macroscopic non-volatile objects that separated from it as a result of its non-gravitational acceleration away from the Sun.

Keywords: Comet tails
An Interesting Solar Flare with the Suppressed Centimeter Wavelength Radio Emission and a Possible Reason for Such a Behavior. In this note, I present a very interesting solar flaring event that occurred on the 2023 February 10th, at about 8:02 UT and the evolution of this M 1.4 class solar flare is shown as observed by different telescopes at different wavelengths. In particular, it will be shown that the flare has a weak signature in the centimeter radio spectrum. As a conclusion, I present my view as to why the flux in the cm radio wavelength range had such a feeble radio signature.

Keywords: Active solar corona, Solar radio emission, Solar flares
The Optical Origin of the Mass-sheet Transformation. In gravitational lensing, the Mass-Sheet Transformation (MST)—or mass-sheet degeneracy—leaves image positions unchanged while scaling magnifications and time delays. The transformation scales the lens mass distribution and superposes a uniform mass sheet, but this formulation offers no clear physical interpretation. Here I show that the MST follows directly from a scaling symmetry that becomes apparent when the ray-trace relation is written in proper-distance coordinates. In this form, the ray-trace relation isolates a geometric focusing term. Subtracting this term from the deflection law defines the Image-Selection Relation (ISR), which determines image positions, magnifications, and differential time delays. The ISR exhibits a scaling symmetry that leaves image positions unchanged while scaling magnifications and time delays. Restoring the geometric focusing term then gives a ray-trace relation related to the original one by the MST.

Keywords: Hubble constant, Strong gravitational lensing, Cosmology
Aperture-averaged Polarimetry of the Second Interstellar Comet 3I/ATLAS within the Snow Line. We have measured the degree of linear polarization of the second interstellar Comet 3I/ATLAS in 2025 November, while the comet was passing within the snow line of the solar system. Our results unambiguously differ from previous observations of the same comet made beyond the snow line by Z. Gray et al., suggesting a change in the microphysics of the coma particles. The model developed by E. Zubko &amp; G. Videen to fit the polarimetric observations of Comet 3I/ATLAS beyond the snow line also can be used to fit our observations within the snow line by omitting the contribution of the water-ice particles. This suggests stability in the microphysics and relative abundances of the refractory species of the 3I/ATLAS coma between the middle of July and late November of 2025.

Keywords: Comets, Interstellar objects, Comae, Coma dust
Residual Infrared Imaging Reveals Faint Spiral Structure in the Lenticular Galaxy NGC 5273. We report the detection of faint spiral-like features in the lenticular galaxy NGC 5273 through residual analysis of archival Spitzer/IRAC images at 3.6 and 8.0 μm. After subtracting smooth elliptical models from each image, the residual at 3.6 μm reveals symmetric, low-surface-brightness spiral arms surrounding the nucleus. In contrast, the 8.0 μm residual map shows only weak central structure, suggesting that the spiral-like features are stellar in origin rather than associated with warm dust or from an old stellar population. This highlights the utility of infrared residual imaging in uncovering hidden disk structure in early-type galaxies.

Keywords: Galaxy structure, Infrared astronomy, Spiral arms, Surface photometry, Infrared galaxies
Exploring the High-mass Regime of Supermassive Black Holes Scaling Relations. We revisit the supermassive black hole scaling relations (SRs) for luminosity, stellar mass, and velocity dispersion for a sample of 72 large and bright galaxies. We performed a photometric analysis of galaxies using a 2D-multicomponent surface brightness modelling with GALFIT. Our main objective is to explore the high-mass regime by including core elliptical galaxies, which were not included in our previous studies. We report that core galaxies present SRs with flatter slopes, which may be related to gas-poor (dry) mergers that play a fundamental role in their formation and evolution. This work highlights the importance of studying trends across the different populations in SRs, namely classical bulges, pseudobulges, lenticular, elliptical, and core galaxies.

Keywords: Galaxy structure, Supermassive black holes, Galaxy photometry, Galaxies
Strong Bars, Strong Inflow: The Effect of Bar Strength on Gas Inflow. Stellar bars are elongated structures in disk galaxies that can torque and funnel gas inward, influencing galaxy evolution. While strong bars are known to induce rapid inflow, the impact of weaker bars remains less certain. We collected spectroscopic data using the Isaac Newton Telescope to analyze 18 nearby galaxies (strongly barred, weakly barred, and unbarred) drawn from Galaxy Zoo DESI. We obtained spatial profiles of equivalent width (EW) and ionized gas velocity dispersion by fitting Gaussian profiles to the Hα emission line. Strongly barred galaxies exhibit a distinctive three-peaked EW[Hα] structure, consistent with inward funneling of gas. Weakly barred systems lack this pattern, which suggests limited inflow. Velocity dispersion distributions further distinguish the bar types, with strongly barred galaxies showing significantly higher values than weakly barred and unbarred systems. These results suggest that strong bars drive gas inflow, while weak bars exert a limited dynamical influence.

Keywords: Galaxy evolution, Galaxy kinematics, Galaxy bars, Disk galaxies
DDO Photometry and the NASA ExEP Star List (2023 Version) for the Habitable Worlds Observatory Mission. David Dunlap Observatory photometry has been used to form a M48 versus C(42─45) color─magnitude diagram of stars listed by the NASA Exoplanet Exploration Program as potential candidates for imaging by the Habitable Worlds Observatory (HWO) mission. A main sequence is well defined, although a number of HWO candidates, often with low levels of chromospheric activity, have evolved significantly away from it. The disposition of stars with respect to metallicity and chromospheric activity is documented in C(45─48) and C(41─42) versus C(42─45) two-color diagrams, the former of which exhibits a relatively tight locus, while the later shows a clear dispersion correlated with stellar metallicity.

Keywords: Main sequence stars, Hertzsprung Russell diagram, DDO photometry
A Bayesian Analysis of Abiogenesis in the Light of Recent Data from K2-18b. In this note I present a Bayesian analysis of the probability of abiogenesis in light of recent measurements by the James Webb Space Telescope of dimethyl sulfide and dimethyl disulfide in K2-18b's atmosphere. I explore how the discovery of a second instance of life beyond Earth would affect the posterior distribution of the rate of abiogenesis λ. Building on the work of D. S. Spiegel &amp; E. L. Turner and D. Kipping, it is no surprise that including the hypothetical K2-18b datum constrains small values of λ, implying that abiogenesis may not be exceedingly rare. However, under the objective prior assumption of D. Kipping, the Earth datum is already strongly constraining λ's posterior distribution and an additional datum does not alter D. Kipping's conclusions.

Keywords: Bayesian statistics, Exoplanets, Earth (planet), Astrobiology, Biosignatures
Simultaneous Positive and Negative Superhumps in the Novalike Cataclysmic Variable GSC 08944−02101. GSC 08944−02101 remained an almost anonymous object until quite recently when J. R. Thorstensen et al. confirmed spectroscopically its nature as a novalike cataclysmic variable and detected positive superhumps in its TESS light curves. Here I report on additional TESS data that revealed negative superhumps to be present simultaneously with their positive kin.

Keywords: Nova-like variable stars, Cataclysmic variable stars
TIC 318249571.01: A New Hot-Jupiter Transiting Planet Candidate from TESS Data. We report the identification of a new transiting planet candidate orbiting TIC 318249571, with a radius of 1.43 ± 0.16 RJ and an orbital period of 2.79656 ± 0.00013 days, matching the characteristics of a hot Jupiter. In this study, we analyze the periodic variations in the lightcurves of the target star across different sectors using established vetting tools, ruling out false-positive scenarios, such as eclipsing binaries or background contamination, and verifying its consistency with a planetary origin.

Keywords: Exoplanet detection methods, Transit photometry, Exoplanets
Symmetric Tidal Tails of Galactic Open Clusters. We present a test of the symmetry of tidal tails in nearby open clusters (OCs) within 1 kpc using Gaia Data Release 3. We fit King density profiles to obtain the tidal radius for each OC and identify leading and trailing tail members according to their projected direction along the cluster orbit. For most OCs, the leading and trailing tidal tails contain comparable numbers of stars. Our results provide strong observational evidence (at the 15σ-level) against the Milgromian dynamics prediction of asymmetric tidal tails and reinforce the conventional Newtonian understanding of tidal escape in OCs.

Keywords: Open star clusters, Milky Way dynamics
Hidden Companions to Intermediate-mass Stars. XXXIII. Unveiling a 2.35M<SUB>⊙</SUB>, 0.06 au Companion to Acamar = Theta Eridani A. Theta Eridani (θ Eri) is a nearby  ρ=8.″3↔425au  visual binary (A+B). The brighter and redder primary (A) is often referred to as a subgiant, but is, in fact, a double-lined spectroscopic binary. Here we report on a VLTI/GRAVITY interferometric observation in which the primary was spatially resolved into a close binary with a projected separation ρ = 1.20 mas ↔ 0.06 au while the secondary (B) is consistent with a single star. Isochrone fitting then implies masses MAa ≃ 2.39M⊙, MAb ≃ 2.35M⊙ and MB ≃ 2.30M⊙ and somewhat expanded radii RAa ≃ 3.9R⊙, RAb ≃ 3.6R⊙ and RB ≃ 3.2R⊙. The very close binary Aa+Ab can explain the TESS lightcurve of θ Eri with a periodicity of 4.1077 days through ellipsoidal modulations. *Based on observations collected at the European Southern Observatory, Chile, Program ID 114.27DS.001.

Keywords: Optical interferometry, Ellipsoidal variable stars, Multiple stars, A stars
A One-class SVM Search for Planetary Nebula Candidates Using AKARI Infrared Photometry. We report the identification of planetary nebula candidates using a One-Class Support Vector Machine applied to high-quality AKARI infrared photometry. The classifier is trained on confirmed Planetary nebulae (PNe) from the Kerber catalog and evaluated on AKARI IRC/FIS sources. The model selects 62 objects consistent with the PN infrared photometry, of which 53 remain viable candidates after removing young stellar objects, active galactic nucleus, and galaxies identified through SIMBAD. This demonstrates the usefulness of anomaly-detection techniques in PN searches across all-sky infrared surveys.

Keywords: Infrared photometry, Planetary nebulae, Interstellar medium, Computational methods
The Nature of BZ Del: Variability Discovered. The star BZ Del had been classified by the Variable Star Index as a suspected variable star. The variable stars section of the Unione Astrofili Italiani undertook an observation campaign between 2025 August and September using ground-based telescopes to determine its variability. Our study showed that BZ Del is an EA system formed by a pair of stars that eclipse each other with a period of 1.985984 days.

Keywords: Eclipsing binary stars, Algol variable stars, Binary stars
A Curious Normalization of the ΛCDM Linear Growth Factor. I note a numerical coincidence in the normalization of the linear growth factor for matter perturbations in flat ΛCDM: the required normalization integral evaluates to unity at a matter density  Ωm⋆≃0.315 , consistent with the concordance cosmological matter density. Over the Planck-allowed range of Ωm this normalization differs from unity by several percent. Any analytic implementation of the growth factor that inadvertently omits this factor therefore acquires an Ωm-dependent amplitude bias that is minimized near  Ωm⋆  and grows to percent-level across the standard parameter range. Although this note does not identify any specific analysis as affected, the behavior of the normalization motivates explicit checks in growth-factor implementations used in multi-probe cosmological inference.

Keywords: Cosmological models, Cosmological parameters, Cosmological perturbation theory, Computational methods, Matter density
Breakthrough Listen Observations of 3I/ATLAS with the Green Bank Telescope at 1─12 GHz. 3I/ATLAS, an interstellar object, made its closest approach to Earth, at ∼1.8 au, on 2025 December 19. On 2025 December 18, the Breakthrough Listen program conducted a technosignature search toward 3I/ATLAS using the 100 m Robert C. Byrd Green Bank Telescope at 1─12 GHz. We report a nondetection of candidate signals down to the 100 mW level.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Interstellar objects
Non-detection of Nightside Emission from HAT-P-26b due to Stellar Contamination. We report a non-detection of nightside emission from the warm super-Neptune HAT-P-26 b. Following a similar approach to that presented by J. Lustig-Yaeger et al. for WASP-17 b, we attempted to extract the nightside emission spectrum using the in-eclipse spectrum removal method to detect planetary infrared excess (PIE). However, our methods did not yield a reliable nightside spectrum for HAT-P-26 b, and instead the results appear consistent with contamination due to small changes in the star between transit and eclipse visits. This null result helps to illuminate astrophysical challenges that complicate applications of the PIE technique and highlight the need for close-in-time transit and eclipse observations for this analysis method.

Keywords: Exoplanet atmospheric composition , Exoplanets, Hot Neptunes, Exoplanet astronomy, Exoplanet atmospheres
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å in Late B-type Stars. XXVI. HD 173524 B (46 Dra B). The weak line of Hg II located at 5677.10 Å is used to measure the mercury abundance in the least massive component of the SB2 HgMn star HD 173524 (46 Dra B). This line is detected at 3σ above the noise in the adjacent continuum. The synthesis of this line confirms a large overabundance of mercury, about +5.00 dex, which remains lower than the excess derived from the 3983.93 Å line in earlier studies. Spectrum synthesis yields estimates of the abundance deficiencies/excesses for 17 other elements. The following excesses/deficiencies are found: helium (−1.70 dex), carbon (−0.70), oxygen (−0.70), magnesium (−1.30), aluminium (−0.70), silicon (−0.22), phosphorus (+0.60), sulfur (−0.30), calcium (0.00), titanium (0.00), chromium (−0.07), manganese (0.15), iron (−0.70), gallium (+2.00), strontium (+0.70), barium (+1.00), platinum (+3.95). These abundances differ for most elements from those derived recently for 46 Dra A using the same spectra and the same analysis technique.

Keywords: Mercury-manganese stars, Chemically peculiar stars
Asteroid (780857) Rodés and Early Spanish Links to the American Astronomical Society. I report the recent naming of the main-belt asteroid (780857) Rodés, discovered by Kazimieras Černis and Richard P. Boyle at Mount Graham Observatory, as announced in the latest bulletin of the IAU Working Group for Small Body Nomenclature. The asteroid honors Luis Rodés Campdera (1881─1939), a Spanish Jesuit astronomer and director of the Ebro Observatory, recognized for his contributions to solar physics and geophysics. I place the naming in historical context highlighting Rodés' participation in three major total solar-eclipse expeditions (1914, 1923, and 1932), his repeated attendance at meetings of the American Astronomical Society (1917, 1923, and 1927), and his sustained involvement in the formative years of the International Astronomical Union, including all six General Assemblies held from its inaugural meeting in 1922 through 1938. These activities illustrate Rodés' active participation in the international astronomical community of the early twentieth century.

Keywords: History of astronomy, Asteroids
Radio Constraints Disfavor Little Red Dots as Scaled-down Super-Eddington Quasars. The Little Red Dots (LRDs) exhibit signatures of active galactic nucleus yet remain undetected in radio and X-ray observations, including deep stacking analyses. These properties have motivated models in which LRDs host supermassive black holes accreting at super-Eddington rates. We test whether LRDs could be scaled-down analogs of super-Eddington quasars like RACS J0320-35 at z = 6.13, whose spectral energy distribution is well reproduced by super-Eddington models. Using observed rest-frame UV luminosities of LRDs, we construct radio predictions for scaled-down versions of RACS J0320-35, then compare them with observational upper limits on radio emission. Most predictions at z &lt; 5 exceed the radio stacking limits of ∼10 μJy for LRDs, except for faint LRDs with UV luminosity ∼1043 erg s−1. However, our predictions remain well below radio detection limits for individual sources in the VLA Sky Survey. We conclude that LRDs are unlikely to be scaled-down versions of super-Eddington quasars, although deeper radio surveys like DSA-2000 will improve constraints.

Keywords: Early universe, Supermassive black holes, Quasars, Active galactic nuclei, Radio sources