Sazuna/UAT_keywords huggingface dataset:
Unveiling Relativistic Jet Dynamics with Dynamic Mode Decomposition. In the present investigation, a magnetized relativistic jet originating from an active galactic nucleus is numerically simulated by solving the relativistic magneto-hydrodynamic equations, employing a high-order finite volume methodology as implemented in the PLUTO solver. The vortical coherent modes, identified through dynamic mode decomposition during the propagation of a relativistic jet through a uniform interstellar medium, exhibit spatio-temporal decay behavior due to strong dissipation induced by the jet head shock. The conversion of jet kinetic energy into thermal energy leads to pronounced dissipation, primarily resulting from the deceleration of the relativistic jet by the jet head shock.

Keywords: Shocks, High-luminosity active galactic nuclei, Interstellar medium, Magnetohydrodynamical simulations
Discovering 7 Potential New Clusters by Visualizing Gaia Data. We created a useful, interactive, 3D visualization tool in MATLAB that can be used by students to explore Gaia data and hunt for over-dense regions in space. We used our tool to visualize the local solar neighborhood out to 50 pc, and developed further code to isolate over-densities using stellar positional information only. We present preliminary findings of 7 highly dense regions of stars within 50 pc of the Sun that have not been previously identified, with 3 of these regions being larger than the Hyades core. Candidate cluster members were selected by applying MATLAB's knnsearch function to data from the Gaia Early Data Release 3 catalog. Our methodology functions as a simple but effective first slice for identifying clusters in 3D space.

Keywords: Gaia
Observing Strategies for Making a 310 MHz Absolute Map with the Green Bank Telescope. We analyze observing strategies for the creation of a 310 MHz absolute map with the Green Bank Telescope. Given limited observing time and other constraints, we face a trade-off between several priorities including covering a wide range of R.A. and decl. and porousness of the map. Our results show that a mix of partial-range azimuth scans and full-range tip scans may represent a useful compromise among these priorities.

Keywords: Radio astronomy, Sky surveys
Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 2 → 3. XXX. Discovery of a 0.79M<SUB>⊙</SUB>, 7.5 au Outer Companion to the 0.20 au HgMn Binary Chi Lupi. Chi Lupi (χ Lup) is a nearby a = 0.20 au, 2.8M⊙ + 1.9M⊙ close binary and the prototype for the class of chemically peculiar mercury–manganese (HgMn) stars. There has been evidence for the presence of a third, outer companion based on variations of the systemic velocity of the inner binary but up to now it had evaded detection. Here we report on a VLTI/GRAVITY observation in which we detected an MC = 0.79M⊙ red dwarf companion at a projected separation ρ ≃ 120 mas ↔ 7.5 au from the close binary, confirming χ Lup as a very compact triple system. The outer companion explains the eROSITA X-ray emission of χ Lup and hints that the inner binary was probably hardened by interacting with a circumbinary disk from which the outer companion also formed. *Based on observations collected at the European Southern Observatory, Chile, Program ID 113.26GM.001.

Keywords: Optical interferometry, Multiple stars, B stars, Mercury-manganese stars
Discovery of a New Satellite or Ring Arc around (50000) Quaoar. On 2025 June 25 UT, a near grazing passage of TNO (50000) Quaoar's known ring Q1R over a 14.9 mag star was predicted for the Monterey Institute for Research in Astronomy's Oliver Observing Station (MIRA-OOS) in California. The event was recorded on two MIRA-OOS telescopes by Richard Nolthenius (RN) and Kirk Bender (KB). No opacity due to Q1R was detected, but instead, a complete occultation lasting 1.23 s was recorded 2.4 minutes before the predicted Q1R graze. We argue this was most likely due to a new satellite—inferred magnitude 28—but cannot yet rule out a third ring with opaque arc.

Keywords: Dwarf planets, Stellar occultation, Planetary rings, Trans-Neptunian objects
Northern Sky Narrowband Survey DR0.2: First [O III] and [S II] Results. Data release (DR) 0.2 of the Northern Sky Narrowband Survey, with a complete set of Hα, [O III], [S II], and continuum data of the northern hemisphere down to a decl. of ‑16°, is presented. To the best of my knowledge, this is the first time ever that [O III] and [S II] data of such a large region have been published. The first part of this article briefly introduces the project and provides an overview of the available resources. In the second part, some remarkable observations are presented: a 17°-large O III arc in Gemini that partially overlaps with the Monogem Ring; the possible closest planetary nebula around the hot subdwarf BD+28 4211 with an apparent diameter of 6°; a faint  2.°7 -large O III ring, which also might be a planetary nebula; and a smaller but relatively bright object in Auriga, which can be seen at all observed wavelength.

Keywords: Sky surveys, Supernova remnants, Emission nebulae, Planetary nebulae, Interstellar medium
TESS Data do not Confirm Gravity Modes in the RR Lyrae Star HH Puppis. A recent study found pulsation frequencies in the RR Lyrae star HH Puppis that were identified as gravity modes, and argued that this phenomenon could explain the Blazhko effect in which pulsations of RR Lyrae stars undergo long term changes in amplitude and phase. The study used ground-based photometry that observed HH Puppis continuously over 136 days. I analysed TESS photometry of both 120 and 200 s cadences and utilised two different software packages for analysis. I do not detect the g-mode frequencies found in the ground-based data set. This casts doubt upon the claim that gravity modes have been observed in an RR Lyrae star.

Keywords: RR Lyrae variable stars, Asteroseismology
MSTAT: A Python Tool for Estimating Spectral Types of Stellar Companions from Differential Photometry. A python-based tool for reading the table of absolute magnitudes for dwarf (O-Y) stars as compiled by M. J. Pecaut &amp; E. E. Mamajek and using this table to determine the most likely spectral type for a companion star has been developed. The tool is designed to take differential magnitudes between the primary star and the secondary star and return the most likely spectral type associated with secondary star. Primarily designed for use with companion detection done by high resolution imaging as part of the TESS follow-up observation program, the python code (https://github.com/mfelsmann/mamajek_spectral_analysis) can be run from a notebook or from the command line and has been made available to community for public use.

Keywords: Software documentation, Multiple stars, Binary stars, Astronomy software, Stellar classification, Companion stars
Statistical Signatures of Intermittency in Relativistic Jet Issuing from Active Galactic Nucleus. In this present study, the propagation of a magnetized relativistic jet from an active galactic nucleus through a uniform interstellar medium is investigated by numerically solving the relativistic magnetohydrodynamic equations using a high-order finite volume method. Furthermore, intermittency signatures are examined using probability density distributions of current density evaluated at various streamwise locations along the jet. Statistical analysis reveals that the front portion of jet will produce intense intermittent compressive current sheets, while inside the cocoon, the fluctuations are more isotropic with strong intermittency.

Keywords: Shocks, Active galactic nuclei, Interstellar medium
Analyzing the Gnevyshev Gap across Odd–Even Solar Cycles (SC 19–25) Using Sunspot Number and Solar Radio Flux (F10.7 and F30). In this study, we analyze the occurrence of the Gnevyshev Gap (GG) across odd- and even-numbered solar cycles, specifically from solar cycle (SC) 19 to SC 25, using Sunspot number and solar radio flux (F10.7 cm and F30 cm) data sets. To reduce short-term fluctuations and highlight long-term trends, a 180 days exponential moving average was applied to both data sets. Our results show that SC 19 to SC 21 does not exhibit a pronounced GG, whereas SC 22 to SC 25 displays a clearly defined GG in some data sets. These findings suggest that the GG can appear either distinctly or weakly in any SC, regardless of whether the cycle is odd- or even-numbered. No systematic correlation is found between the prominence of the GG and the odd-even parity of the SCs, and this result is statistically significant based on the Wilcoxon signed-rank test.

Keywords: Solar cycle
Classifying Microlensing Events from ROME/REA. The Roman Galactic Bulge Time Domain Survey will complete our census of free-floating and bound exoplanets by detecting microlensing events from timeseries photometry. But the literature on classifying microlensing events is limited compared with other types of transients. Building on recent developments in machine learning techniques, this research describes the preparation and training of an eXtreme Gradient Boosting classifier to detect microlensing events in the recent data release from the ROME/REA Survey. We evaluate the classifier's ability to distinguish microlensing from various other categories of stars, both variable and constant. In this note we discuss the preparation and filtering of the training data set and present the results of our preliminary model. One unusual feature of this data set is that it combines data from multiple telescopes, and discuss the impact this has on the training of classifiers.

Keywords: Gravitational microlensing exoplanet detection, Multi-color photometry, Classification, Galactic bulge, RR Lyrae variable stars, Long period variable stars, Variable stars, Gravitational microlensing, Cataclysmic variable stars
Estimation of the Albedo and Diameter of the Asteroid (16960) 1998 QS<SUB>52</SUB> Using the Polarimetric Method. Polarimetric observations of the potentially hazardous Apollo asteroid (16960) 1998 QS52 were carried out in the region of the inversion angle. The polarimetric slope of the phase curve of the degree of linear polarization at the inversion point was determined. Using the generalized calibration "h-albedo slope," the albedo of the asteroid (16960) 1998 QS52 was estimated, which is pv = 0.158 ± 0.034. The diameter of the asteroid was also estimated, which is D = 3.3 ± 0.3 km.

Keywords: Asteroids
Unveiling the Dynamics of Supernova: A Use of Dynamic Mode Decomposition. In the present investigation, a supernova remnant (SNR) propagation inside the interstellar medium (ISM) is numerically simulated by solving the compressible magneto-hydrodynamic equations, employing a high-order finite volume methodology as implemented in the PLUTO solver. Flow features associated with the SNR propagated inside non-uniform ISM, is discussed thoroughly. The vortical coherent modes, identified through dynamic mode decomposition during the propagation of a SNR through a non-uniform ISM exhibit spatio-temporal decay behavior due to strong dissipation induced by the reverse shock and forward shock, respectively.

Keywords: Supernova remnants, Interstellar medium, Magnetohydrodynamical simulations
Meet Arjuna 2025 PN<SUB>7</SUB>, the Newest Quasi-satellite of Earth. When the first asteroid in an Earth-like orbit, 1991 VG, was found in 1991 December by the Spacewatch Project, it was argued that it was a candidate interstellar space probe, but it is now thought to be natural. Over three decades later, the number of known asteroids in Earth-like orbits exceeds 100, forming the so-called Arjuna secondary asteroid belt, the closest to Earth. Out of the Arjunas and not counting those which can be temporarily captured as mini-moons of Earth, quasi-satellites are our closest companions. Here we show that 2025 PN7 is a quasi-satellite, alongside known objects Cardea, Kamo'oalewa, 277810, 2013 LX28, 2014 OL339, 2023 FW13. They are all engaged in a 1:1 mean-motion resonance with our planet, but they are not gravitationally bound to it.

Keywords: Solar system, Asteroids, Asteroid dynamics
Measuring Bar and Spiral Arm Pattern Speeds in MaNGA Barred Spiral Galaxies. We measure independent pattern speeds for bar and spiral arms in 98 barred spiral galaxies with Mapping Nearby Galaxies at Apache Point Observatory data. Some galaxies exhibit statistically different pattern speeds (Ωbar ≠ Ωspiral), while others have statistically equal pattern speeds. We find no trends of ΔΩ with stellar mass or galaxy color. Our results are consistent with a Universe which might have some bar-driven spirals (ΔΩ = 0), but some spirals in barred galaxies must be tidally driven or self-excited (ΔΩ ≠ 0). These results demonstrate the potential for ΔΩ measurements to constrain spiral arm formation mechanisms.

Keywords: Galaxy structure, Spiral arms, Galaxy evolution, Barred spiral galaxies, Galactic bar
An Evaluation of Autoencoder Based Models for Galaxy Deblending. Galaxy deblending is a critical challenge in astronomical surveys, particularly in large-scale surveys where overlapping galaxies complicate accurate observation and analysis. This paper evaluates autoencoder-based deep learning models for galaxy deblending, comparing convolutional autoencoders (CAE), Variational Autoencoders (VAE), and VAE-Generative Adversarial Networks. We find that CAEs have the best performance. We discuss the performance of the models as well as possible areas of improvements.

Keywords: Galaxies, Sky surveys, Astronomy image processing
No Evidence of Intrinsic Linear Polarization in Nova Vel 2025 (V572 Vel). We report on polarimetric observations of V572 Vel (Nova Vel 2025) conducted on 2025 June 26th and July 21st, shortly after its nova eruption was discovered. Our measurements in the IC band revealed an average linear polarization of 1.60% ± 0.03% at position angle (PA) of 132 .° 2. To distinguish between intrinsic and interstellar polarization, we also measured 86 field stars in the nova's vicinity, finding an average polarization of 1.25% ± 0.61% at a nearly identical PA of 132°. The strong consistency between the nova's polarization and that of the surrounding field stars suggests that the observed polarization is predominantly interstellar in origin. We found no significant evidence of an intrinsic polarization component, which would typically arise from an asymmetric distribution of ejected material. Further multiband observations are recommended to confirm these findings.

Keywords: Starlight polarization, Cataclysmic variable stars, Novae
Mapping Gamma-Ray Bursts: Distinguishing Progenitor Systems Through Machine Learning. We present an analysis of gamma-ray burst (GRB) progenitor classification through their positions on a Uniform Manifold Approximation and Projection plot, constructed by M. Negro et al., from Fermi-GBM waterfall plots. The embedding plot has a head–tail morphology, in which GRBs with confirmed progenitors (e.g., collapsars versus binary neutron star mergers) fall in distinct regions. We investigate the positions of various proposed sub-populations of GRBs, including those with and without radio afterglow emission, those with the lowest intrinsic luminosity, and those with the longest lasting prompt gamma-ray duration. The radio-bright and radio-dark GRBs fall in the head region of the embedding plot with no distinctive clustering, although the sample size is small. Our low luminosity GRBs fall in the head/collapsar region. A continuous duration gradient reveals an interesting cluster of the longest GRBs (T90 &gt; 100 s) in a distinct region of the plot, possibly warranting further investigation.

Keywords: Gamma-ray bursts
The Evolving Light Variations and Periodicities of Betelgeuse Five Years after the Great Dimming. Betelgeuse is the brightest red supergiant visible from Earth. Betelgeuse has nearly 200 yr of visual observations as well as systematic photoelectric and CCD data that indicate semi-regular light variations. In mid-February 2020, Betelgeuse surprisingly faded to its faintest and coolest ever recorded—dubbed the "Great Dimming" (V +1.61 mag). Previously, Betelgeuse had multiple periodicities with dominant periods of 185, 380–420, and 2000–2200 days. We find that even before this dimming, a new dominant period of 208 ±12 days superseded the 400 days periodicity. Additionally present is a 2000–2200 days Long Secondary Period (LSP) that remains consistent throughout the dimming. The LSP has recently been proposed to arise from a close-orbiting binary companion star. Contrary to expectation, however, the LSP light minimum appears to be occurring several months earlier than predicted. We present results of quantitative period analyses and draw tentative conclusions.

Keywords: M supergiant stars, Multi-periodic pulsation, Supergiant stars, Cataclysmic variable stars, Multi-periodic variable stars, Variable star period change
A Descriptive Taxonomic Nomenclature for Intermediate-sized Trans-Neptunian Object Spectra. Trans-Neptunian objects (TNOs), icy remnants of planet formation orbiting beyond Neptune, comprise a dynamically and compositionally diverse population of &gt;5000 known members. An extensive body of literature focuses on the dynamical structure of the trans-Neptunian region. Less information is available on TNO compositions due to the difficulty carrying out spectral observations of objects dozens of astronomical unit from the Sun. The James Webb Space Telescope has revolutionized our understanding of TNO surface compositions by enabling near-infrared spectroscopy out to ∼5 μm. Clustering and principal component analysis reveal that the majority of intermediate-size TNOs fall into one of three broad spectral classes. Here we propose a more descriptive taxonomy based on the most spectrally prominent features for each class: H2O-, CO2-, and organics-types. Additional categories may arise via future JWST observations; the naming convention described here is extensible to any newly identified (sub-)categories based on prominent spectral features.

Keywords: Surface composition, Classification systems, Infrared spectroscopy, Trans-Neptunian objects
SPHEREx Discovery of Strong Water Ice Absorption and an Extended Carbon Dioxide Coma in 3I/ATLAS. In mid-August 2025, 0.75–5.0 μm SPHEREx imaging spectrophotometric and ancillary NASA-IRTF/SpeX 0.7–2.5 μm low-resolution spectral observations of 3I/ATLAS were obtained. The combined spectrophotometry is dominated by features due to water ice absorption and CO2 gas emission. A bright, ∼3' radius CO2 gas coma was clearly resolved, corresponding to Qgas,CO2∼9.4 × 1026 molecules s‑1. From the SPHEREx photometry, we put conservative, preliminary 3σ upper limits on the gas production rates for H2O and CO of 1.5 × 1026 and 2.8 × 1026 molecules s‑1, respectively. No obvious jet, tail, or trail structures were found in SPHEREx images. If we assume all observed 1 μm flux is scattered light from a pv = 0.04 albedo spherical nucleus, then the radius would be Rnuc ∼ 23 km. Given the nucleus size limit Rnuc &lt; 2.8 km from D. Jewitt et al., we conclude &gt;99% of the measured SPHEREx continuum flux is from coma dust.

Keywords: Small Solar System bodies, Infrared spectroscopy, Ice spectroscopy, Carbon dioxide, Coma dust, Interstellar objects, Exocomets, Comet volatiles , Infrared photometry, Near infrared astronomy
Meet the Neighbors: Gas Rich "Buddy Galaxies" are Common around Recently Quenched Massive Galaxies in the SQuIGG<inline-formula> <mml:math><mml:mover><mml:mrow><mml:mi>L</mml:mi></mml:mrow><mml:mrow><mml:mo>→</mml:mo></mml:mrow></mml:mover></mml:math> </inline-formula>E Survey. In this work, we characterize the environments of massive ( log(M⊙/M⋆)∼11.2 ) z ∼ 0.7 post-starburst galaxies (PSBs) by studying serendipitously detected CO(2–1) emitters found in targeted observations of the Studying QUenching in Intermediate-redshift Galaxies: Gas, angu L→ ar Momentum, and Evolution (SQuIGG L→ E) sample. We report 31% ± 6% of the galaxies from this survey host nearby gas-rich "buddies" with stellar masses ≥1010 M⊙ and molecular gas comparable to their central PSBs ( MH2∼1010M⊙ ), but ∼0.8 dex lower stellar mass (∼1010.4M⊙). Based on their location in position-velocity space, each buddy is consistent with being bound to the haloes of their SQuIGG L→ E host galaxies. We compare to the UniverseMachine model and find that SQuIGG L→ E galaxies host a typical number of neighbors for their stellar mass, suggesting that PSBs live in environments typical of co-eval similarly massive galaxies.

Keywords: Galaxy quenching, Quenched galaxies, Post-starburst galaxies, Galaxy environments
Recommendations for the Vera C. Rubin Observatory Early Science Schedule. The NSF-DOE Vera C. Rubin Observatory announced plans to modify the release timetable for the final data preview (DP2) and its first data release (DR1). The Observatory solicited community feedback regarding potential paths forward, as supplied by the Observatory, in light of the schedule change. In this Note, the Rubin Observatory LSST Solar System Science Collaboration provides its feedback concerning these options and the impact on solar system science. We strongly favor transition into survey operations and the release of the existing Science Validation commissioning data and alerts at the earliest possible opportunity.

Keywords: Sky surveys, Small Solar System bodies, Solar system astronomy
Morphologies of Changing Look Active Galactic Nuclei Host Galaxies in Galaxy Zoo. Changing look AGN (CLAGN) are highly variable Active galactic nuclei (AGN) that gain or lose broad emission lines over a few months or years. However, we still do not understand what really causes these CLAGNs to occur. In this work, we compare CLAGN to normal AGN host galaxies and galaxies without AGN in the GalaxyZoo data set, a citizen science project in which volunteers classify galaxies in astronomical images based on their morphologies and structures. We compared the fraction of spirals, ellipticals, and galaxies with merger features between these AGN types. Our results indicate that the morphological distribution of CLAGN host galaxies is statistically consistent with those of both AGN and non AGN host galaxies. This supports the idea that internal processes or accretion events may be driving the observed variability in CLAGN rather than the host galaxy's morphology.

Keywords: AGN host galaxies, Active galactic nuclei, Time domain astronomy
CZEV522: A Chromospherically Active EA. In this study, we present the reclassification of the variable star CzeV522, classified by the Variable Star Index (VSX) as an undefined variable (VAR). The SSV-UAI-GRAV section (Variable Stars Section of the Unione Astrofili Italiani) planned an observation campaign with 10 ground-based telescopes in 2025 June and July in order to understand its nature. From the observations made, combined with the available All-Sky Automated Survey for Supernovae and Zwicky Transient Facility surveys, it was found that the star CzeV522 is an algol-type eclipsing variable with a period of 1.515073 days. Thanks to the SSV-UAI-GRAV observation campaign, which is more accurate than the surveys, it was possible to identify an extra-eclipse variation independent of mutual eclipses and due to the non-uniformity of one of the two components (spots) and chromospheric activity. The star has been reclassified at the VSX as EA+BY.

Keywords: Algol variable stars, BY Draconis stars, Variable stars, Starspots
A Color–Magnitude Diagram in the DDO Photometric System. A signature two-color diagram of the DDO photometric system plots C(45–48), which is sensitive to surface gravity for cool stars, versus C(42–45), which correlates with effective temperature. The extent to which this two-color diagram mimics a Hertzsprung–Russell diagram is explored. To this end, a color–magnitude diagram (CMD) that plots an absolute magnitude M48 versus color C(42–45) is presented for a sample of field stars for which high-precision DDO photometry and Gaia DR3 parallaxes are available. Such a DDO CMD has seen little use to date.

Keywords: Hertzsprung Russell diagram, DDO photometry, Giant branch