Sazuna/UAT_keywords huggingface dataset:
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å. XXIII. HD 90264 B (L Car). The weak line of Hg II located at 5677.10 Å is detected in UVES spectra of the HgMn star HD 90264 B as a feature absorbing about 1% of the continuum. The synthesis of this line yields a mercury abundance which is slightly lower than the abundance derived from the 3983.93 Å line. Line synthesis is used to measure the abundances of several other elements for the first time. The following excesses/deficiencies are found: helium (‑1.10 dex), magnesium (‑1.00 dex), phosphorus (+1.65), titanium (‑0.52), chromium (‑1.30), manganese (0.00), iron (‑0.46), gallium (+2.54), baryum (+0.90) and mercury (+4.40). A conservative uncertainty on the excesses/deficiencies is estimated to be ±0.10 dex. HD 90264 B may be a phosphorus–gallium–mercury-rich star rather than a HgMn star. More abundances are needed to clarify the nature of this star.

Keywords: Mercury-manganese stars, Chemically peculiar stars
Kinematics of the Wind-bubble G2.4+1.4 around the WR 102 Star: A First Approach. We present a glimpse of the kinematics of the Wolf–Rayet (WR) nebula G2.4+1.4 surrounding the subtype WO2 star WR 102. Here, we report the profiles of the lines [O III], Hα, [N II] and [He II] obtained through high-resolution spectroscopy from the OAN-SPM (Based on observations collected at the Observatorio Astronómico Nacional (OAN), operated in Mexico by UNAM). We found that the expansion velocities associated with those lines range from 15 to 25 km s‑1. The complex and filamentary structure of the source reveal that WR 102 is embedded into the interstellar medium, causing its peculiar shape.

Keywords: Wolf-Rayet stars, Gaseous nebulae, Spectroscopy
A Simplified Model for Free-atmosphere Seeing Estimation Using NCEP/NCAR Data at the ORM. We present and validate a simplified physical model for estimating free-atmosphere seeing (ɛfree) using NCEP/NCAR reanalysis data at the Roque de los Muchachos site. We compare the computed values to MASS-DIMM measurements across 235 common nights from 2008 May to 2009 September, and for a well-sampled night (2008 November 18). The seasonal comparison gives root mean square error (RMSE) =  0.″67  and r = 0.56. On the selected night, applying smoothing and bias correction lowers the RMSE to  0.″07  and raises r to 0.85. These findings support the use of this lightweight model for astroclimatology and preliminary site evaluation in areas lacking field measurements. A dual-panel figure summarizes both results.

Keywords: Astronomical seeing, Atmospheric effects
A Practical Framework for Weight Map Construction in CCD Photometry. This note presents a practical formulation for constructing weight maps in CCD photometry, accounting for various noise contributions under the assumption of statistical independence. We provide complete equations for both electron-count and analog-to-digital unit-based imaging data, along with simplified expressions for different observational conditions.

Keywords: CCD observation, Astronomy data analysis
Testing the Solar Lithium Abundance with a Survival Model. The lithium abundance [A(Li)] in FGK-type stars remains widely debated due to complex depletion mechanisms. The Sun presents a particularly puzzling case, with current photospheric measurements yielding A(Li)⊙ = 0.96 ± 0.05 dex, significantly lower than the predicted for stars of its age, as estimated in earlier studies. Our survival analysis—developed in a previous work—suggests A(Li)⊙ = 1.71 ± 0.03 dex, revealing a 7–8σ discrepancy with observations. Here, we showcase the results of our model specifically for the Sun and briefly discuss the potential causes for the additional depletion mechanisms that could explain its unexpectedly low Li content.

Keywords: Galactic archaeology, Solar abundances, Solar physics, Survival analysis, Galactic abundances, Astrostatistics strategies
Empirical Globular Cluster Ridgeline Construction on Gaia Data. We present a new method and a corresponding code to compress the color–magnitude diagram (CMD) of a globular cluster into a representative curve, called a ridgeline, that can be more readily compared to isochrone models, among other applications. This compression method preserves the physical properties of the cluster, including the morphology of the CMD.

Keywords: Globular star clusters, Open source software, Gaia
Candidate AGN Extended Emission-line Regions in the Rubin Virgo Field. As both a test and demonstration of the power of the Legacy Survey of Space and Time (LSST) data for this purpose, we present a set of 5 candidate active galactic nucleus-ionized extended emission-line regions in the Rubin Virgo field, based on visual color selection. Although still pending spectroscopic confirmation, these illustrate the depth of detection of the LSST data compared to existing broadband surveys, even for these irregularly shaped objects with almost pure emission spectra.

Keywords: AGN host galaxies, Active galaxies
A Weak-moderate Solar Cycle 25 is Confirmed. Solar Cycle 25 appears to have reached its maximum in 2024 October, with a smoothed sunspot number peak of 160.8. This suggests that the cycle is already in its declining phase and confirms that it is weaker than the average solar cycle. These findings are consistent with early predictions based on statistical properties of past solar cycles. It supports the view that, for now, "solar climatology" remains our most reliable approach for forecasting solar activity.

Keywords: Solar cycle
Visible Spectral Slope of Saturn's Rings from Ground-based Observations and Comparison with Cassini Data. We present visible wavelength observations of Saturn's rings conducted using 1.6 m ground-based telescope. The goal is to assess long-term compositional changes in the rings by comparing spectral characteristics with data acquired by the Cassini spacecraft. Reflectance spectra from 450 to 900 nm were obtained during four nights in 2021 and 2022. Spectral slopes, sensitive to water ice purity, were derived for two wavelength ranges: 450–550 and 550–900 nm. Our measured slopes agree well with values previously reported from Cassini's VIMS data, suggesting minimal compositional change over the past decade. In addition, no clear correlation is found between spectral slope and the orbital position of Enceladus. These results support the reliability of visible-wavelength ground-based monitoring as a complementary tool to past spacecraft observations.

Keywords: Optical observation, Saturn, Enceladus, Planetary rings, Ground telescopes
The Nature of an Unidentified X-Ray Source in the 7 Ms Chandra Deep Field-South Catalog. In the 7 Ms Chandra Deep Field-South catalog, only one source, XID 912, was highly significantly detected in X-rays but had no formally reported counterparts in the UV, optical, infrared, or radio bands. We identified its potential JWST and Very Large Telescope VIMOS counterparts and measured the corresponding aperture photometry to construct its spectral energy distribution (SED). We fitted this SED using CIGALE. The results indicate that the source is most likely an off-nuclear ultraluminous X-ray source, rather than a background active galactic nucleus.

Keywords: Ultraluminous x-ray sources, Active galactic nuclei
Radially Extended C I Emission in the IM Lup Protoplanetary Disk Uncovered with Matched Filtering. The IM Lup protoplanetary disk shows tentative evidence of an external photoevaporative wind based on its unusually extended and diffuse 12CO gas. Only shallow [C I] 1–0 observations exist toward IM Lup, which show a more compact radial distribution than that of 12CO, despite the expectation that atomic carbon should trace the outer interface of UV-irradiated 12CO. In this research note, we present a novel use of matched filtering to constrain the maximum extent of the underlying C I gas in IM Lup. We find evidence for C I emission at large radii (r ≈ 700–950 au) beyond what was previously detected in the image plane (r ≈ 600 au). Further deep and spatially resolved imaging of C I in IM Lup and other systems will be essential for disentangling the disk- versus wind-driven components of C I to better understand how line emission traces photoevaporative processes.

Keywords: Astrochemistry, Protoplanetary disks, Circumstellar disks, Exoplanet formation, Planet formation
Neutral Oxygen in z ∼ 2–3 Galaxies: Probing Galaxy Evolution Through Faint Emission-line Diagnostics. The faint [O I]λ6302 emission line is sensitive to the ionizing spectrum, shocks, and diffuse ionized gas (DIG) in star-forming galaxies. It was found frequently in early JWST surveys of z &gt; 2 galaxies, indicating that it is a promising method for probing ionization mechanisms and tracing low-ionization gas in distant objects. We analyze 21 z ∼ 2–3 galaxies from the Keck Baryonic Structure Survey and construct [O I] line-ratio diagrams. There is a notable offset between the z ∼ 2–3 galaxies and z ∼ 0 galaxies from the Sloan Digital Sky Survey in the O1-BPT. The offset and the inability of even low-metallicity models to capture the high-redshift locus suggest that DIG and shocks may be contributing to observed [O I] emission. To confirm this scenario, a larger and more representative study is required.

Keywords: Galaxies, Emission line galaxies, Spectroscopy
Analysis of Trajectories to 3I/ATLAS with a Comet Interceptor-like Spacecraft. We consider whether or not the newly identified Interstellar Object (ISO) 3I/ATLAS could have been reached by the ESA Comet Interceptor (CI) spacecraft, if it was already operating in space today. We find that the necessary Δv significantly exceeds that available to CI, and 3I would have had to be discovered at unrealistically large heliocentric distance to enable a minimum Δv transfer. CI will have to be very lucky to encounter an ISO. A future ISO-dedicated mission following a similar concept is realistic, if it has a Δv capability comparable to current large interplanetary missions, and it is sent to an ISO that does not pass on the opposite side of the Sun from the Earth, as 3I does.

Keywords: Flyby missions, Interstellar objects
Analytic Modeling of Inspiral Gravitational Waveforms from Binary Black Hole Mergers. I present an analytic approximation to the inspiral gravitational waveform generated by a binary black hole merger using leading-order post-Newtonian dynamics. Employing the quadrupole formula and chirp mass scaling relations, I simulate the h+ and h× polarization components of the strain and visualize the characteristic chirp signal. The model, while simple, captures key physical trends and provides an intuitive understanding of gravitational wave signals. The full Python implementation used to generate the waveform is publicly archived with a DOI on Zenodo and is available under the MIT License. This allows others to use, modify, and extend the code for educational or exploratory purposes.

Keywords: Gravitational wave astronomy
Pulsation Blip in the roAp Star HD 60435 Detected by SALT and TESS. HD 60435, a member of the rapidly oscillating Ap class of pulsating stars, was recently reported to be the first star to be observed to entirely cease pulsating. This conclusion was drawn from photometric TESS observations that have less sensitivity to pulsational variability than spectroscopic time series data. To that end, we acquired three epochs of time resolved spectra, to coincide with TESS observations, with the Southern African Large Telescope to test for the continued cessation of pulsation. We found the star to show a pulsation blip at a single epoch, then continue to be non-variable at two further epochs. The same signal, and lack thereof, was also seen when analyzing the nearly contemporaneous TESS photometry. *Based on observations made with the Southern African Large Telescope (SALT).

Keywords: Oblique rotators, Rapidly oscillating Ap star, Photometry, Spectroscopy, Asteroseismology, Chemically peculiar stars
The Complex System of ASAS J110528+0545.0. In this study, we present the reclassification of the star ASAS J110528+0545.0, known as a DSCT-type variable star in the Variable Star Index. The SSV–UAI–GRAV research section of the Unione Astrofili Italiani (UAI) has planned an observation campaign with eight ground-based observatories in 2025 April and May to study the accuracy of its classification. From the observational sessions obtained, combined with the available data from the All-Sky Automated Survey for Supernovae and ASAS-3 surveys, the star ASAS J110528+0545.0 has been reclassified as ELL/RS. The orbital period of the pair of stars was found to be 0.421875 day with a variation of 0.07 mag V, while the long-term study of the surveys revealed a slow but detectable variation in the average magnitude caused by the chromospherically active nature of one of the two stars or by surface spots.

Keywords: RS Canum Venaticorum variable stars, Starspots, Ellipsoidal variable stars, Variable stars
Publication Efficiency in Astronomy: A Global GDP Based Comparison (2019–2023). This comment examines the relationship between GDP and astronomy publications for 106 countries in 2019 and 103 countries in 2023. The data show a strong positive correlation: countries with higher GDP typically produce more astronomy papers. To analyze this relationship, we divided the GDP range into four bands, making it easier to compare countries with similar economic output. We also examined regional patterns in astronomical research output. We introduce a new metric, publication efficiency, defined as the number of astronomy papers per unit of GDP. This measure reveals which countries produce unusually high levels of astronomy-specific output relative to their economic size, often due to targeted funding, effective policies, or other favorable conditions. On a global scale, astronomical publication efficiency was 0.37 ± 0.56 publications per billion USD of GDP in 2019 and 0.39 ± 0.49 in 2023.

Keywords: Astronomy education, Astronomical research
Study of the Waves at the Clouds of Venus with the Space Mission Akatsuki. Venus' atmosphere has been studied for years, yet the mechanism behind atmospheric super-rotation remains unclear. Waves, potential contributors to this phenomenon, are frequently observed in the clouds but require further quantitative analysis. This study uses basic image processing on data from Akatsuki's UltraViolet Imager to identify and characterize waves near the diurnal cloud tops (∼70 km). These are preliminary findings of a broader ongoing investigation into cloud-top waves during the Akatsuki mission.

Keywords: Planetary atmospheres, Venus, Atmospheric clouds
Discovery of 6 New Orbital Periods for Classical Novae. I report newly discovered orbital periods for 6 classical novae, based on recent light curves from the TESS satellite. These periods are 0.1900636 ± 0.0000057 days for V1391 Cas, 1.020869 ± 0.000018 for FQ Cir, 0.07488825 ± 0.00000016 for V462 Lup, 0.166229 ± 0.000013 for V6620 Sgr, 0.12317997 ± 0.00000010 for V572 Vel, and 0.4538473 ± 0.0000054 days for V615 Vul. Further, I report a non-orbital period 0.04360 day for V1717 Sco, and I confirm an earlier reported period discovery of 0.0686517 day for V906 Car.

Keywords: Novae
Peculiar Stellar Ages of the Peculiar Dwarf Galaxy NGC 5474. Using deep, narrowband imaging of the nearby peculiar spiral galaxy NGC 5474, we present stellar age information across its disk and offset bulge. As shown in earlier work on M101, our narrowband filters measure age-sensitive absorption features such as Balmer absorption. We separate our study of NGC 5474 into its main disk containing its offset bulge, and the faint outer disk. We show that the main disk is relatively well-mixed in ages, showing no radial age changes. Meanwhile, the offset bulge is distinct from the main disk, showing only old ages. We explore the ages of the outer disk as a function of angle, showing that it is relatively young with the side towards M101 showing the youngest ages. We interpret this in the context of the M101–NGC 5474 interaction and the potential extragalactic nature of the offset bulge.

Keywords: Galaxy ages, Narrow band photometry, Dwarf galaxies, Galaxy stellar content
One Million Open-source Cislunar Orbits. Cislunar space, encompassing the region from geosynchronous orbit to beyond the Moon, is poised to become a cornerstone for future exploration, scientific discovery, and national security. Missions in this region, spanning durations from weeks to decades, require robust infrastructure and reliable transit capabilities. The complex gravitational influences of the Moon, Sun, and planets, along with thermal radiation from Earth and the Sun, lead to significant trajectory deviations, resulting in kilometer-scale errors within days. Leveraging the high-performance computing resources at Lawrence Livermore National Laboratory (LLNL), we have simulated one million high-fidelity cislunar trajectories, now publicly available via LLNL's Green Data Oasis and the Unified Data Library. Generated using the open-source Space Situational Awareness Python package, these trajectories match the precision of commercial tools such as AGI's Systems Tool Kit and NASA's General Mission Analysis Tool. This data set is a valuable resource for reference, statistical analysis of cislunar orbit populations, and training machine learning models for rapid orbit classification with minimal observational input. Preliminary analysis reveals stable bands in Keplerian element space, particularly around five geosynchronous radii across a range of inclinations and eccentricities. Beyond this threshold, the Moon's influence disrupts most unassisted orbits, though co-orbiting L4/L5 Lunar Trojans persist throughout the six-year simulation.

Keywords: Distributed computing, Celestial mechanics, Orbit determination, N-body simulations, Astronomical simulations
CACHAI's First Module: A Fully Customizable Chord Diagram for Astronomy and Beyond. We introduce CHORDDIAGRAM, the first module of Custom Axes and CHarts Advanced Interface (CACHAI), a fully customizable visualization toolkit for PYTHON. CHORDDIAGRAM creates publication-ready chord diagrams with fine control over edge styles, node colors, and layout, addressing key limitations of existing tools. Features include per-element styling, correlation thresholding, targeted highlighting, adaptive node spacing, log-scaled link thickness, and more. While broadly applicable, we showcase its use in astronomy by visualizing (anti-)correlations among stellar parameters and kinematics. CHORDDIAGRAM forms the foundation of the CACHAI suite, available via pip (https://pypi.org/project/cachai), and at https://github.com/DD-Beltran-F/cachai, where the user can find a detailed documentation and examples.

Keywords: Interdisciplinary astronomy, Astronomy data visualization, Astronomy data analysis, Astronomy software
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å. XXIV. HD 27376 (41 Eri). The weak line of Hg II located at 5677.10 Å is detected in a FEROS spectrum of the SB2 star HD 27376 as a feature absorbing about 1% of the continuum. The synthesis of this line yields a mercury abundance which is slightly lower than the abundance derived from the 3983.93 Å line. Line synthesis is used to measure the abundances of sixteen elements for the first time for one of the components, arbitrarily called HD 27376 A. The following excesses/deficiencies are found: helium (‑0.92 dex), carbon (‑0.22), oxygen (‑0.15), magnesium (0.00), aluminum (‑1.30), silicon (0.00), phosphorus (+1.48), sulfur (‑0.52), titanium (0.48), chromium (0.40), manganese (1.40), iron (0.30), gallium (+2.78), xenon (+3.85), baryum (0.00) and mercury (+4.85). A conservative uncertainty on the excesses/deficiencies is estimated to be ±0.10 dex. The HgMn status of this star is reinforced.

Keywords: Mercury-manganese stars, Chemically peculiar stars
A Lightweight and Educational Simulation of Gravitational Lensing by an SIS Galaxy Cluster Using Python. Strong gravitational lensing probes both cosmology and astrophysical structure, yet students and newcomers often encounter steep technical barriers. Here I present a carefully constructed, educational Python simulation of strong lensing by a Singular Isothermal Sphere, tailored for maximum clarity and pedagogical value. The simulation visualizes both the geometric configuration (Einstein radius, source position) and the resulting lensed image of a Gaussian background source. It reveals key features of strong lensing—multiple images, arcs, and Einstein rings, using pure analytic relations, robust logic, and modern visualization. The code relies only on numpy and matplotlib, making it exceptionally accessible for classroom or outreach use. The approach provides an ideal starting point for teaching, rapid demonstration, or as a foundation for further lensing model exploration in research or public science settings. All code and the demonstration figure are published with this article (see Code and Data Availability).

Keywords: Gravitational lensing
A Comprehensive Energy-resolved Timing Analysis of XTE J1550–564. We present a study of low-frequency quasi-periodic oscillations (LFQPOs) in the Galactic black hole binary XTE J1550–564 during its 1998 outburst using data from RXTE. Light curves in eight energy bands from 0.1 to 13 keV were analyzed with Fourier techniques to produce energy-resolved power spectra. Each spectrum was modeled with three Lorentzians along with a power-law continuum. From these fits, we measured the peak frequency ( νMAX ), quality factor (Q), and fractional rms amplitude (r) for each QPO. Our results show that r increases with energy, indicating that QPOs become more detectable at higher energies, while Q and  νMAX  remain largely unchanged. This suggests that the trend in r is not due to changes in the QPO's width or coherence, but rather to an increase in the continuum level with energy, which adds more power under the QPO features. These findings provide constraints for future modeling of LFQPO behavior.

Keywords: Accretion, X-ray astronomy, Black holes, Timing variation methods, X-ray transient sources
Comparing X-Ray Emission Line Fluxes of NGC 5548 to NGC 1068. The Unification Model of Active galactic nucleus (AGN) suggests that all AGN galaxies should exhibit similar line ratios in their spectra. NGC 5548, a Seyfert I, underwent obscuration—similar to naturally obscured Seyfert II galaxies—due to an outflowing accretion wind, resulting in absorption. As per the Model, a Seyfert I and a Seyfert II should show similar flux ratios during their respective obscuration states. In this note, we present a comparison of emission fluxes between NGC 5548 and NGC 1068, a Seyfert II. We present the CLOUDY prediction of NGC 5548, which underpredicts the line ratios compared to observations, likely due to spectral energy distribution choices. The differing observed line ratios of NGC 5548 and NGC 1068 suggest additional unknown factors in the unification model.

Keywords: X-ray active galactic nuclei, Active galactic nuclei, Emission line galaxies
Systematic Biases in BPT Diagram Classifications from Emission-line Signal-to-noise Cuts. The Baldwin–Phillips–Terlevich (BPT) diagram is a widely used diagnostic for separating star-forming galaxies from galaxies hosting active galactic nuclei (AGN). The BPT diagram requires reliable measurements of four key emission lines. Most studies impose a per-line signal-to-noise (S/N) threshold on these emission line fluxes, but this S/N threshold is often unreported, and rarely tested as a source of bias. Here, ∼104 galaxies from SDSS DR19 are used to evaluate how the classification is affected by selection criteria at S/N &gt; 2, 3, 5, and 10. I find that raising the threshold from S/N &gt; 2 to S/N &gt; 10 increases the star-forming fraction from 69% to 85% and decreases the composite and AGN fractions by ∼50% relative. These changes are systematic, reflecting the preferential loss of AGN and composite systems with weak Hβ or [N II]. Thus it is recommended that BPT-based studies explicitly state S/N cuts and exercise caution when comparing results based on different thresholds.

Keywords: Star forming regions, Active galactic nuclei