Sazuna/UAT_keywords huggingface dataset:
Real-time Early Solar System Evolution in RW Auriga A: A New Major Dimming Event has Started in 2025 February. In this Note1 we introduce the problem of the highly dynamic T Tauri system RWAurA, and, using new analyses of lightcurves and imaged jet structures, its potential for understanding early solar system formation processes. In the following Note2 we describe how new physical modeling strengthens our arguments for the dynamic behavior of RWAurA arising from a migrating, differentiated, tidally disrupted Vesta-sized planetesimal. In the past two decades, the system's lightcurve has undergone extreme excursions, dropping by up to 3 mag versus the normal median level. Of most importance here is the lightcurve event of 2014─2020, and the new major lightcurve downturn event that started in 2025 February (C. M. Lisse et al. 2025 CBAT). As we are finding that RWAurA is a solar system-sized laboratory allowing real-time study of early solar system formation processes, the new system-wide event needs to be observed on daily timescales for the next few years.

Keywords: Infrared spectroscopy, Light curves, Stellar jets, Mantle, T Tauri stars, Planetary migration, Time domain astronomy, Planetesimals, Stellar accretion disks, Planetary cores, Optical observatories
Refining the Migrating Differentiated Planetesimal Disruption Model for Classical T-Tauri Star RW Aur A's Dimming Events. C. M. Lisse et al. (2022) published a near-infrared time domain spectral study of the dimming events in RW Aurigae A (RWAurA). Emission from the protostellar surface, protostellar atmosphere, accretion disk, and jets was reported, with the most pronounced changes seen in jet emission amplitude due to siderophilic elements. RWAurA also evinced a strong increase in protostellar atmosphere emission due to accretion by lithophilic elements. This segregation of emission features was noted to match the evaporation susceptibility of a differentiated planetesimal's core versus the thermal stability of rocky mantle solids in the environment of the inner accretion disk wall region, and a fortuitous planetesimal collisional disruption was hypothesized. Here we refine this event as the consequence of the tidal disruption of an inwardly migrating differentiated planetesimal containing a molten core, and call for re-monitoring of the system in the light of H I:Fe II:Ni II:S II:N I:He I during the new major dimming event that started in early 2025.

Keywords: Infrared spectroscopy, Light curves, Stellar jets, Mantle, T Tauri stars, Planetary migration, Time domain astronomy, Planetesimals, Stellar accretion disks, Planetary cores
Wind Power as a Technosignature on M-dwarf Planets. We suggest that the large-scale deployment of wind turbines on an M-dwarf planet could produce observable technosignatures. Motivated by observations of hypersonic wind velocities on WASP-127 b, we note that the atmospheres of such planets could serve as vast reservoirs of energy for an extraterrestrial civilization. A large-scale deployment of wind turbines in a hypersonic environment would produce heated shock waves in the hypersonic stream, cause strong frictional heating from the rotation of the blades, and be a source of infrared radiation. We mention possible scenarios that could lead to the deployment of wind turbines on a gas giant and also note that similar features could exist on terrestrial M-dwarf planets. The idea that aerodynamic peculiarities could be a technosignature is worth keeping in mind as ground- and space-based exoplanet observations continue to improve.

Keywords: M dwarf stars, Technosignatures, Astrobiology, Search for extraterrestrial intelligence, Exoplanet atmospheres
A New Velocity-dispersion Profile for the Core of 47Tuc. As part of an effort to identify astrometric evidence of an intermediate-mass black hole in 47Tuc, we construct a new velocity-dispersion profile for the innermost 30″ of the cluster using WFPC2 and WFC3 images spanning an unprecedented 22 yr time baseline. The WFPC2 exposures were processed using a deep-learning centering procedure as well as an improved astrometric calibration of the camera. The resulting velocity-dispersion profile has a 1″ spatial resolution and error bars that compare very favorably to prior studies.

Keywords: Globular star clusters, Space astrometry, Proper motions
Abundance Determinations for HD 32964 A (66 Eri A). Abundances or their upper limits are derived for 19 elements for 66 Eri A, the most massive star in the double-lined SB2 system 66 Eri. The following excesses/deficiencies are found: helium (−1.00 dex), carbon (−0.68), neon (−0.30), magnesium (−0.30), silicon (−0.74), phosphorus (0.00 upper limit), calcium (−0.96), scandium (−0.48), titanium (−0.16), chromium (−0.46), manganese (+0.08), iron (−0.70), gallium (0.00 upper limit), strontium (−0.21), ytrium (+0.00 upper limit), zirconium (0.00 upper limit), xenon (0.00 upper limit), baryum (+0.78) and mercury (0.00 upper limit). All elements up to chromium are deficient which is quite unusual. Only baryum is overabundant. The abundance pattern of 66 Eri A differs strikingly from that of 66 Eri B. Radiative diffusion alone cannot account for such abundance differences between stars which were born together and have identical properties.

Keywords: Stellar abundances
Identifying Binary Stars in the HARPS Database with Gaia Astrometry, Photometry, and Radial Velocities. I identify binaries among stars monitored by the High-Accuracy Radial velocity Planetary Searcher spectrograph using radial velocities (RVs), Gaia astrometry, and photometry. Out of 141 Gaia-selected targets, I identify 68 photometric binaries and report RV variability in 138 stars. Gaia Data Release 4 (DR4) is expected in mid 2026, and these results provide candidates well-suited for analysis with Gaia DR4's non-single star astrometric solutions.

Keywords: Astrometric binary stars, Radial velocity, Binary stars, Gaia
Comparison of Australasian Tektites with Australasian Microtektites and BeLaU Spherules Recovered from the Ocean. The Australasian strewn field covers more than 15% of Earth's surface, consisting of tektites and microtektites. Australasian tektites from Southeast Asia and Australia, as well as microtektites recovered from deep sea sediments and Antarctica, are established to be derived from upper continental crust (UCC) sediments. An expedition to retrieve remnants of bolide CNEOS 2014 January 8 (IM1), held in the Pacific Ocean, was in proximity to the known extent of the Australasian strewn field, and yielded "BeLaU"-spherules, whose compositions did not match most well-studied solar system material. We therefore report precise and comprehensive elemental data for Australasian tektites to compare their elemental abundances to those of Australasian microtektites from deep sea sediments, and BeLaU. Our findings corroborate previous studies that Australasian tektites and microtektites closely resemble the elemental abundance patterns of the UCC. Meanwhile, the elemental patterns of the BeLaU-spherules are distinct from the Australasian tektite/microtektite compositions.

Keywords: Tektites, Australites, Solar system terrestrial planets, Solar system
Iskay2: Signal Extraction of the Kinematic Sunyaev─Zel'dovich Effect Through the Pairwise Estimator: Pipeline and Validation. The peculiar motions of massive halos probe the distribution of matter in the universe, the gravitational potential, and the history of cosmic structure growth. The kinematic Sunyaev─Zeldovich (kSZ) effect offers a robust observational window into these properties. The pairwise kSZ estimator probes the pairwise momentum of groups of galaxies by cross-correlating cosmic microwave background (CMB) maps with spectroscopic galaxy catalogs, using galaxies to trace the positions of dark matter halos. This note introduces iskay2, an efficient pipeline designed to apply the pairwise kSZ estimator to maps of the CMB and large galaxy catalogs. Pairwise kSZ measurements obtained using this pipeline are compared to previously published results and are shown to be consistent within statistical expectations. This pipeline will enable high-precision measurements of the pairwise kSZ utilizing galaxy catalogs like DESI combined with past, current and next-generation high-resolution CMB experiments such as ACT, SPT and the Simons Observatory.

Keywords: Galaxy clusters, Cosmology, Large-scale structure of the universe, Observational cosmology, Cosmic microwave background radiation, Dark matter
Comment on "Temperatures of Jupiter's Upper Atmosphere: The Role of the Planetary Magnetic Field". A recent study has invoked mid-latitude ion drag as a process to resolve the so-called "energy crisis" in Jupiter's thermosphere. I point out a potential problem in the methodology of this study that calls into question this conclusion. In the study, the assumption of zero electric field at mid-latitudes leads to a corotational drag on the thermosphere, which is key to the conclusions. A more rigorous accounting of the relevant physics would lead to an anti-corotational drag on the thermosphere, which would most likely have the opposite effect. I suggest in outline a possible improvement to the methodology that would avoid the problem.

Keywords: Planetary ionospheres, Theoretical models, Planetary atmospheres, Jupiter, Planetary science, Planetary magnetospheres
A Fast Folding Algorithm Search for Long-period Pulsars in Unidentified Bright Radio Sources. We have used a fast folding algorithm to search for radio pulsations at long periods (1─30 s) from 75 unidentified radio sources. These sources were originally identified in the NRAO VLA Sky Survey as radio bright, unresolved, and highly linearly polarized, suggesting that they could be previously undetected pulsars. These targets had been observed with the Green Bank 43 m radio telescope and searched for repeating pulses using standard Fourier techniques as well as for dispersed single pulses. This new search of the data is more sensitive to large periods and small duty cycles than the previous Fourier search. We found no promising signals and extend the flux density limit of the original search of ∼3 mJy to this larger spin period range.

Keywords: Surveys, Pulsars
Extreme Scattering Events in Radio Observations of Point Sources: Do Coronal Mass Ejections from Flare Stars Contribute to the Scattering?. Extreme scattering events (ESEs) are observed as large fluctuations in radio flux from point-like sources. ESEs may originate in interstellar structures with linear dimensions of ∼1 au, electron densities of 10─100 cm−3, and transverse speeds of order 100 km s−1. These parameters overlap with corresponding parameters associated with solar coronal mass ejections (CMEs). I suggest that stellar CMEs from flare stars may contribute significantly to the ESE phenomenon.

Keywords: Interstellar scattering, Stellar flares, Stellar coronal mass ejections
A Diagram of Intermittent Habitability for Eccentric Exoplanets. I introduce a diagram that combines semimajor axis, eccentricity, and stellar properties to quantify the fraction of orbital period spent within habitable zone (HZ). The diagram identifies whether an orbit lies fully within, fully outside, or partly overlaps the HZ. The diagram reveals that exoplanets sometimes classified as outside the HZ actually spend more than half of their orbit within it. Climate modeling further suggests that planetary systems may retain habitable conditions even outside formal HZ boundaries. These cases should be considered when selecting targets for biosignature searches.

Keywords: Habitable zone, Elliptical orbits, Eccentricity
Unexpected Stellar Chemistry as a Marker of Atypical Stellar Evolution?. Accurate stellar ages are crucial for galactic archeology, but cannot be measured directly. Evolved red giant stars offer a solution, since their lifetimes can be inferred from their masses. Mass measurements often rely on mass proxies, such as the surface carbon-to-nitrogen ratio ([C/N]) after the first dredge-up. But this relationship is not consistent for all stars. Understanding the systematics behind these [C/N] outliers is essential for improving mass and subsequent age measurements. We analyze additional elemental abundances, such as those of s-process elements, that may indicate binary interactions. We find significant differences between typical and outlier stars, suggesting atypical or binary evolution histories for outlier stars. By accounting for such complexities in this method, more accurate stellar ages and a clearer picture of the Milky Way's formation and evolution will be understood.

Keywords: Binary stars, Abundance ratios, Red giant clump, Red giant stars, Milky Way evolution
An Inventory of Resolved Stellar Companions in the Ariel Target List. Stellar companions impact many facets of planet formation and mature planetary systems. In this note, we investigate planet-hosting stars that are currently potential targets for the upcoming Ariel mission, and present an inventory of their stellar companions. We examine several catalogs that used Gaia astrometry to identify companions with similar phase-space parameters, and that therefore have a high probability of being gravitationally bound. The agreement between catalogs is good; the false-negative rate is ∼16%. We also search for stellar companions beyond 1 kpc and present four new candidate companions. All Gaia-resolved companions referenced in this work have now been added to the ExoFOP archive to facilitate future planet confirmation efforts.

Keywords: Wide binary stars, Visual binary stars, Gaia, Binary stars
A Stellar Stream around the Spiral Galaxy Messier 61 in Rubin First Look Imaging. We present the first stellar stream discovered with the Vera C. Rubin Observatory, around spiral galaxy M61 (NGC 4303) in Virgo First Look imaging. The stream is narrow, radially-oriented in projection, and ∼ 50 kpc long. It has g-band surface brightness μg ∼ 28 AB mag arcsec−2, color g − z ∼ 1.0, and stellar mass M⋆ ∼ 2 × 108M⊙. This dwarf galaxy interaction may have provoked the M61 starburst, and foreshadows the bounty of accretion features expected in the ten-year Rubin Legacy Survey of Space and Time.

Keywords: Starburst galaxies, Galaxy dark matter halos, Spiral galaxies, Tidal disruption, Dwarf galaxies, Galaxy interactions, Galaxy tides, Galaxy structure, Galaxy stellar halos, Tidal tails, Galaxies, Low surface brightness galaxies
Modeling Globular Cluster Counts with Bayesian Latent Models. We present a Bayesian latent model to describe the scaling relation between globular cluster populations and their host galaxies, updating the framework proposed in R. S. de Souza et al. Globular cluster counts are drawn from a negative-binomial (NB) process linked to host stellar mass, augmented with a newly introduced Gaussian observation layer that enables efficient propagation of measurement errors. The revised formulation preserves the underlying NB process while improving computational tractability. The code snippets, implemented in Nimble and PyMC are released under the MIT license at this repository ✎.

Keywords: Globular star clusters, Astrostatistics techniques
High-spectral Resolution, Multi-wavelength Center-to-limb Observations of the Sun. The center-to-limb variations (CLVs) of photospheric and chromospheric spectral lines were obtained in 2025 July and August using drift scans from the echelle spectrograph of the 0.7 m Vacuum Tower Telescope at the Observatorio del Teide (ODT) in Tenerife, Spain. This instrument can observe four spectral regions simultaneously, enabling multi-line spectroscopy with high spectral resolution of various activity features and the quiet Sun in the lower solar atmosphere. The initial results of Hα observations demonstrate the diagnostic potential of drift scans obtained with a ground-based, high-resolution telescope. Data products include spectroheliograms and maps of physical parameters such as line-of-sight velocity, line width, and line-core intensity. The combination of the CLV from photospheric and chromospheric lines, as well as the wide range of formation heights of the selected lines, renders this dataset ideal for characterizing stellar and exoplanet atmospheres.

Keywords: Center to limb observations, Solar physics, Spectroscopy, Drift scan imaging, Solar chromosphere
Estimating Gravitational-wave Amplitudes from Neutron Stars Using the RNS Code. I present a computational study of gravitational-wave (GW) amplitudes from rotating neutron stars using relativistic stellar-structure models. The analysis employs the publicly available RNS code to compute rapidly rotating neutron-star equilibria in full general relativity. I calculate equilibrium sequences for multiple realistic equations of state (EOS) and derive the corresponding continuous-wave GW strain amplitudes. The results illustrate how the stiffness of the EOS influences the mass─radius relation, the moment of inertia, and the expected strain h0, providing a bridge between nuclear physics and observational GW astronomy.

Keywords: Neutron stars, Gravitational waves
Further Identification of δ Scuti, γ Doradus Stars, and Eclipsing Binaries with TESS. I analyzed Transiting Exoplanet Survey Satellite (TESS) data for 95,469 stars with effective temperatures between 6500 and 8100 K and TESS magnitudes of 11 .m 202─12 .m 45 to search for δ Scuti and γ Doradus variables. This survey resulted in the discovery of 16,745 new variable stars, comprising 7129 δ Scuti stars, 5283 γ Doradus stars (including 1485 hybrids), 2495 eclipsing binaries (340 of which host pulsating components), 2092 rotational variables, 25 RR Lyrae stars, and a few other types.

Keywords: Delta Scuti variable stars, Pulsating variable stars, RR Lyrae variable stars, Eclipsing binary stars, Gamma Doradus variable stars
Discovery of an Uncatalogued Emission Nebula Around HD 213231 in Cepheus. I report the discovery of a previously uncatalogued emission nebula surrounding the B-type star HD 213231 in the constellation Cepheus. The object is centered at  αJ2000=22h28m30.s57 ,  δJ2000=+58∘50'52.″78  and exhibits strong Hα and [S II] emission with faint traces of [O III]. The initial indication of nebulosity appeared in a 114 hr narrowband SHO image of the Sh2-135 region obtained in summer 2025 using a Sky-Watcher Esprit 100ED telescope with a ZWO ASI2600MM Pro camera and Antlia 2.5 nm filters. Follow-up imaging with a Celestron 9.25" EdgeHD telescope (0.7× reducer) confirmed the presence of a compact, ionized structure through 44 hr of integration (Hα 10 hr, [S II] 24 hr, [O III] 10 hr). The nebula's morphology and high Hα/[O III] ratio are consistent with a small H II region likely ionized by the nearby B-type star. Faint diffuse emission at the same location is visible in the Digitized Sky Survey (DSS color) via Aladin Lite, supporting the conclusion that this is a genuine, previously unrecognized emission nebula.

Keywords: Emission nebulae, Astrophotography, Interstellar medium, Nebulae, H II regions
What ZTF Saw Where Rubin Looked: Anomaly Hunting in DR23. We present results from the SNAD VIII Workshop, during which we conducted the first systematic anomaly search in the Zwicky Transient Facility fields also observed by LSST commissioning camera during Rubin Scientific Pipeline commissioning. Using the PineForest active anomaly detection (AD) algorithm, we analysed four selected fields (two galactic and two extragalactic) and visually inspected 400 candidates. As a result, we discovered six previously uncatalogued variable stars, including RS CVn, BY Draconis, ellipsoidal, and solar-type variables, and refined classifications and periods for six known objects. These results demonstrate the effectiveness of the SNAD AD pipeline and provide a preview of the discovery potential in the upcoming LSST data.

Keywords: Supernovae, Transient detection, Time domain astronomy, Time series analysis
A Simple Procedure for Generating a Kappa Distribution in PIC Simulation. For kinetic modeling of plasma processes in space, a rejection-sampling procedure for generating a Kappa distribution in particle-in-cell simulation is proposed. A Pareto distribution is employed as an envelope distribution. The procedure only requires uniform variates, and its acceptance efficiency is ≍0.73─0.8.

Keywords: Monte Carlo methods, Computational methods, Algorithms, Plasma physics
A Strong Gravitational Lensing Model of PSZ2 G118.46+39.32. We present the first strong gravitational lensing model for the cluster PSZ2 G118.46+39.32 (z = 0.3967) using new NIRCam imaging from the Strong LensIng and Cluster Evolution (SLICE) JWST program. We leverage the broad coverage of the SLICE ultrawide JWST filters to identify new lensed galaxies, some of which are not visible in Hubble Space Telescope, to model the cluster's mass distribution. The model was constructed with a total of 11 multiply imaged systems, decomposed into 30 images with 60 clumps used as strong lensing constraints. PSZ2 G118.46+39.32 shows a clear bimodal structure, indicating that it may be undergoing a merger. The predicted mass distribution of the model aligns with the X-ray gas in the cluster, suggesting it is in a pre-merger state.

Keywords: Galaxy clusters, Strong gravitational lensing
When Space-based TESS Misses the Signal Gravity Modes from Antarctic Ground-based PAIX. A recent Research Note by T. Love reported no detection of gravity modes in the RR Lyrae star HH Puppis from TESS photometry. I show that this null result is fully consistent with the limitations of TESS for this target (single-sector baseline, window function, and redder passband) and does not undermine my previously reported detections. The g0 mode at 2.0013 day−1 is not an observational artifact: it deviates strongly from known aliasing frequencies, exhibits harmonic structure and nonlinear coupling with the fundamental radial mode, and is absent in other RR Lyrae stars observed with PAIX, using the same site, instrument, and reduction pipeline. These features confirm its astrophysical origin. High-resolution, continuous and uninterrupted PAIX photometry reaffirms the robustness of the gravity-mode detection and highlights the importance of complementary ground-based observations for revealing low-amplitude asteroseismic signals that remain undetectable in space-based survey data.

Keywords: Stellar astronomy, RR Lyrae variable stars, Stellar pulsations
Embedding Reliability for Unsupervised Classification of Gamma-Ray Burst Progenitors from Prompt Gamma-Ray Emission. We present a statistical method based on scDEED to assess the reliability of a 2D embedding showing a low-dimensional representation of the distribution of Gamma-Ray Bursts (GRBs) detected by the Fermi Gamma-ray Burst Monitor. The original dataset consists of 12 waterfall plots for each event, which contain key information about the prompt emission of each GRB. The dataset's dimensionality is first reduced to a 30-dimensional latent space using an autoencoder, and subsequently to 2D using UMAP. While the methodology and results are discussed in a previous work, here we introduce a statistical approach to evaluate the reliability of the final 2D distribution based on the scDEED algorithm. Our analysis shows that the 2D embedding demonstrates overall good reliability, with more than 90% of the events classified as trustworthy.

Keywords: Gamma-ray bursts, Dimensionality reduction