Sazuna/UAT_keywords huggingface dataset:
The Critical 9365 Å Diffuse Interstellar Band and C<inline-formula> <mml:math><mml:msubsup><mml:mrow></mml:mrow><mml:mrow><mml:mn>60</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math> </inline-formula> Association. The detection of interstellar C 60+  has been debated for 30 yr. The contested attribution of a weaker diffuse interstellar band (DIB) at 9365 Å was re-evaluated here on the basis of a Pearson correlation relative to 9577 Å, which was previously tied to C 60+  by diverse collaborations. An assessment of 11 sightlines revealed a high correlation amongst 9365–9577 Å equivalent widths (r = 0.93 ± 0.05), after contamination from an adjacent line was mitigated using both numerical integration and Gaussian fits. In tandem with a recent separate study's high-r evaluation linking 9577–9632 Å across a sizable baseline: three interrelated DIBs matching C 60+  laboratory findings were independently reaffirmed (9365, 9577, 9632 Å). Yet further investigations are required to strengthen the case via two other weak DIBs disputedly linked to C 60+ , particularly owing to potential overlapping lines arising from an expansive chemical space (PAHs).

Keywords: Astrochemistry
TeV Emission in NGC 4278: Shock Energetics Insufficient, Compact Origin Favored. The Large High Altitude Air Shower Observatory recently detected TeV emission from the low-luminosity active galactic nucleus (LLAGN) NGC 4278. Integral-field spectroscopy with MEGARA revealed ionized outflows on hundred-parsec scales with kinetic power  E˙shock∼1038  erg s‑1, well below the TeV luminosity Lγ ≳ 1041 erg s‑1. The implied efficiencies, η ≳ 1000, are far above unity, showing that shocks cannot account for the TeV emission. Contemporaneous Fermi-Large Area Telescope and Swift data, consistent with a compact synchrotron self-Compton jet component, favor a nuclear origin. NGC 4278 is the first low-ionization nuclear emission-line region (LINER)/LLAGN of its class detected at TeV energies, a benchmark for LINERs with outflows and a prime target for the Cherenkov Telescope Array Observatory. I conclude that the TeV photons arise from a compact nuclear accelerator, while optical outflows trace larger-scale jet–ISM interactions that coexist but do not power the TeV radiation.

Keywords: Gamma-ray sources, Active galactic nuclei, Radio jets
Determination of the Abundances of the HgMn Star HD 53244 (γ CMa). The weak line of Hg II located at 5677.10 Å is not detected in a series of ESPaDOnS I profiles of the bright HgMn star HD 53244. Line synthesis is used to measure the abundances of twenty elements. The following excesses/deficiencies are found: helium (‑1.00 dex), carbon (‑0.70), oxygen (‑0.30), neon (+2.70), magnesium (‑0.60), silicon (‑0.30), phosphorus (+1.60), titanium (+0.54), chromium (+0.15), manganese (+1.73), iron (‑0.30), gallium (0.00), strontium (0.00), ytrium (0.00), zirconium (0.00), xenon (+2.70), baryum (0.00), praseodymium (+2.23) and mercury (+3.81). A conservative uncertainty on the excesses/deficiencies is estimated to be ±0.10 dex.

Keywords: Mercury-manganese stars, Chemically peculiar stars
JAM 1: Discovery of a New Candidate Evolved Planetary Nebula in Deep [O III] and Hα Imaging. We report the discovery of a previously uncatalogued extended emission nebula, hereafter JAM 1, detected in ultra-deep [O III] and Hα narrowband imaging. Located at 18h56m25s, + 30°42'06″  (J2000), JAM 1 exhibits a nearly spherical morphology with an angular diameter of ≈864″ ( 14.'4 ). The object is conspicuous in [O III], while in Hα it is immersed in diffuse Galactic emission. The southeastern edge is diffuse, while the northwestern rim is brighter, suggestive of interaction with the interstellar medium. No central star candidate has been identified in Gaia DR3, Pan-STARRS, or GALEX. The morphology, size, and emission-line dominance favor classification as a candidate evolved planetary nebula. Spectroscopic follow-up is required to confirm this classification.

Keywords: Stellar-interstellar interactions, Planetary nebulae, Interstellar medium wind
High Proper Motion Object Discoveries from the Backyard Worlds: Cool Neighbors Citizen Science Project. We report the discovery of 11 low mass star and brown dwarf candidates identified via their high proper motions by the Backyard Worlds: Cool Neighbors citizen science project. Finding and classifying ultracool dwarfs is a crucial step in better understanding and describing substellar populations. Backyard Worlds: Cool Neighbors combines machine learning pre-selection of ultracool dwarf candidates with large-scale crowdsourcing to reveal previously overlooked cold, nearby objects within the archival Wide-field Infrared Survey Explorer (WISE) data set. Our new discoveries range in photometrically estimated spectral type from M1 to L8, and illustrate the value of continued searches for faint high proper motion objects in the WISE data set.

Keywords: Brown dwarfs, Astrometry, Low mass stars, Proper motions, Photometry, Catalogs
A Long-term Quasiperiodic Disk Around the Be Star QR Vul. Be stars are non-supergiant B stars that rotate rapidly and show evidence of an equatorial decretion disk. The disks are variable in time and strength, but are usually unpredictable. We report on spectra from the Be Star Spectra archive that indicate that the Be star QR Vul has a quasi-periodic property in its disk strength, where the largest disk phases seem to be modulated on a ∼4.36 yr cycle. We speculate on two possible causes.

Keywords: Early-type emission stars, Be stars, Variable stars, Circumstellar disks
Mass- and Metallicity-dependent Changes in Stellar Hydrogen Luminosity after Low-mass Brown Dwarf Engulfment. Brown dwarf engulfment is a common occurrence in stellar systems. However, its dynamics have not been fully studied. By using Modules for Experiments in Stellar Astrophysics to simulate the engulfment of low-mass brown dwarfs of Jupiter-composition and 1 RJ by 100 R⊙ red giant branch (RGB) stars, we aim to shed some light on the immediate effects of brown dwarf engulfment on RGB stars. We varied engulfed brown dwarf mass (13, 16.5, and 20 MJ) and initial stellar metallicity (z = 0.001, 0.01, and 0.04) to study their impacts on the hydrogen luminosity of the engulfing RGB star. We found prominent dips of up to ≍17.8%, and post-dip spikes of up to ≍2.6%, in the hydrogen luminosity of the star immediately after engulfment in all cases, with more pronounced dips and post-dip spikes for higher-mass brown dwarfs and lower-metallicity stars.

Keywords: Brown dwarfs, Stellar luminosities, Red giant branch, Red giant stars
Comparative Analysis of Polarization in Interstellar Comet 3I/ATLAS with Distant Solar System Comets. We analyze polarimetric measurements of the interstellar Comet 3I/ATLAS reported recently by Z. Gray et al. Comparison with distant solar system comets suggests no significant difference in the microphysics of the dust populating its coma. The extended range of the polarimetric phase function places constraints on the real part of refractive index of particles in the 3I/ATLAS coma at Re(m) ≍ 1.387 ± 0.085, suggesting the presence of a considerable amount of water ice, exceeding volume of Mg-rich silicates by several times.

Keywords: Comets, Interstellar objects, Comae, Coma dust
Unveiling the Kinematic Substructure of the Pleiades with Network Analysis. I apply network analysis to Gaia DR3 astrometry of the Pleiades to investigate the cluster's internal kinematic structure. Using a Mahalanobis distance graph in proper-motion space, I identify the largest connected component of 1556 stars at a threshold of τ = 4.0. Louvain community detection then partitions this network into eight subgroups of sizes 741, 629, 75, 55, 39, 6, 6, and 5. The five highest-betweenness stars are highlighted; they play disproportionate structural roles in connectivity between distinct kinematic subgroups, rather than implying any specific dynamical mechanism. This graph-based approach provides a compact way to characterize substructure in nearby open clusters using Gaia astrometry.

Keywords: Stellar kinematics
A Refined Orbital Ephemeris for the Intermediate Polar FO Aquarii and Evidence for a Period Derivative. We combine more than 40 yr of eclipse timings of the intermediate polar FO Aqr and derive new orbital ephemerides. The eclipse times are best fit with a second order polynomial, implying an 8σ detection of a period derivative. The results show that the orbital period of FO Aqr is currently increasing, with a derivative of  P˙=6.65±0.81×10−11 .

Keywords: Eclipsing binary stars, DQ Herculis stars, Cataclysmic variable stars, Orbital evolution
Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 1 → 2. XXXI. Discovery of a 0.64M<SUB>⊙</SUB>, 3.4 au Companion to Psi Scorpii. Stars with both a significant astrometric acceleration and no detected companion are candidates for having a compact object companion but they must first pass through the sieve of near-infrared interferometry. Psi Scorpii (ψ Sco) is a nearby A-type star that has amassed a number of astrometric anomalies while previous observations did not detect any companion. Here we report on a VLTI/GRAVITY observation in which we detected a companion to ψ Sco with a K band flux ratio of 3.5% ± 0.1% at a projected separation ρ = 78 mas ↔ 3.4 au. Isochrone fitting implies masses MA ≃ 1.95M⊙ and MB ≃ 0.64M⊙ and a system age of 630 Myr. The orbital motion with a period of about 10 yr can explain the astrometric anomalies of ψ Sco. *Based on observations collected at the European Southern Observatory, Chile, Program ID 113.26GM.001.

Keywords: Optical interferometry, Multiple stars, A stars
A Notable Fireball Observed by Miguel Romero Martínez on 1918 August 31 in Southwestern Spain. We report and contextualize a remarkable eyewitness account of a bright fireball observed in southwestern Spain on 1918 August 31 by the Spanish amateur astronomer Miguel Romero Martínez. His detailed description, published in an early 20th-century Spanish astronomical journal, contributes to the historical record of meteor phenomena prior to the era of instrumental monitoring.

Keywords: Bolides
Assessing the Potential Visibility of Comets like C/2025 R2 (SWAN) by NEO Surveyor. We investigate the potential detectability of the newly discovered and close-approaching long-period comet C/2025 R2 (SWAN) by NEO Surveyor using the NEO Surveyor Survey Simulator (nss). The comet, with a minimum orbital intersection distance with Earth of 0.047 au, was discovered just one month before its closest-approach to Earth and a few days after its perihelion. We simulate "bare nuclei" test objects without cometary activity and find that NEO Surveyor, if the mission were currently operating, may have discovered C/2025 R2 90─150 days before perihelion for a nucleus with diameter d ≥ 0.6 km. This range would represent a multi-month improvement over the real-life timeline. These results highlight NEO Surveyor's capabilities to provide early-warning for close-approaching comets, complement ground-based surveys, and enable long-term monitoring of cometary activity, all of which are crucial for planetary defense and solar system science.

Keywords: Long period comets, Comets, Sky surveys, Small Solar System bodies
The Late Infrared Spectrum of the Very Slow Nova V5558 Sagittarii. A 0.8─5.0 μm spectrum of V5558 Sagittarii from 2013 September, more than six years after outburst, shows a still active nova emitting a rich coronal line spectrum. Lines exist for multiple ionization states of Al, S, Si, Ca, and Ti and coronal lines are present for Mg, Na, and Ni as well. Modeling of the emission line region indicates a temperature for the exciting source of at least 4 ×105 K. The presence of coronal lines such as [S IX] 1.2520 μm and [Al IX] 2.0450 μm suggests that V5558 Sgr would have been a source of Super Soft X-rays at the time of our measurement.

Keywords: Classical novae
Discovery of an O III Envelope Extending around NGC 2818A. NGC 2818A is one of only a handful of planetary nebulae to have an established association with a galactic star cluster. Such associations allow a highly accurate determination of the distance and thus other physical characteristics of the planetary nebulae, making them particularly interesting subjects for study. This paper discusses the discovery of an expansive O III envelope surrounding NGC 2818A.

Keywords: Stellar mass loss, Gaseous nebulae, Planetary nebulae, Emission nebulae
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å. XXV. HD 32964 B (66 Eri B). The weak line of Hg II located at 5677.10 Å is not detected in a series of ESPaDOnS I profiles of the bright HgMn SB2 star HD 32964 (66 Eri). This non-detection sets a limit on the abundance of mercury below which this line ceases to be useful. Line synthesis is used to measure the abundances of twenty elements in one component of the system, 66 Eri B, the HgMn star. The following excesses/deficiencies are found: helium (─0.70 dex), carbon (─0.52), oxygen (─0.70), neon (─0.30), magnesium (─0.40), silicon (─0.70), phosphorus (0.00), calcium (─0.85), scandium (─0.48), titanium (+0.36), chromium (+0.52), manganese (+0.52), iron (─0.70), gallium (0.00), strontium (─0.09), ytrium (+2.00), zirconium (0.00), xenon (0.00), baryum (+1.60) and mercury (+4.73). The status of 66 Eri B as a HgMn star is reinforced.

Keywords: Mercury-manganese stars, Chemically peculiar stars
A Search for Coma in TESS Observations of Interstellar Comet 3I/ATLAS. The Transiting Exoplanet Survey Satellite observed the interstellar comet 3I/ATLAS in 2025 May─June. Using this extensive data set, we coadded more than 9000 images, in two groups, to look for extended coma that would unambiguously reveal cometary activity. The radial profiles in both coadded groups are comparable to inactive objects, indicating that no extended coma was detected. However, the brightness of 3I in these observations, in light of results from Hubble Space Telescope observations, suggests that there is coma in the central point-spread function. This means that if activity was sustained for any significant length of time, the dust in the coma must have been ejected at very low velocities (&lt;10 m s−1).

Keywords: Comet nuclei, Space observatories, Interstellar objects, Comae
Cluster Catalog Validation with Multiwavelength Data. The Legacy Survey of Space and Time will provide a ground-breaking data set for cosmology, but to achieve the precision needed, the data, data reduction, and algorithms measuring the cosmological data vectors must be thoroughly validated and calibrated. In this note, we focus on clusters of galaxies and present a set of validation tests for optical cluster finding algorithms through comparison to X-ray and Sunyaev─Zel'dovich effect data. As an example, we apply our pipeline to compare the performance of the red-sequence Matched filter Probabilistic Percolation and Wavelet Z Photometric cluster finding algorithms on Dark Energy Survey data. We investigate metrics of completeness, centering, and scaling relations. We find more than 88% of South Pole Telescope clusters with both algorithms, and 8% or fewer of the clusters are found to be miscentered. The intrinsic scatter in both samples is low compared to X-ray temperature.

Keywords: Galaxy clusters, Cosmology, Large-scale structure of the universe
Averaged Disturbing Function for the Saturn─Titan─Hyperion 4:3 Resonance. The averaged disturbing function for the Saturn─Titan─Hyperion system near the 4:3 mean-motion resonance is presented, following the formalism of C. D. Murray &amp; S. F. Dermott. Secular and first-order resonant terms are explicitly derived, with direct and indirect contributions separated. Using current orbital elements, numerical coefficients confirm the system's proximity to resonance. Resonant angles are defined and used to express the perturbative terms. A graphical representation illustrates the relative strengths and phase behaviors of each term, providing insights into the dynamical coupling between Titan and Hyperion.

Keywords: Celestial mechanics, Saturnian satellites, Orbital resonances
Photometric Analysis of Radio-emitting Tidal Disruption Event Host Galaxies. Supermassive black holes (SMBHs) lie at the centers of most large galaxies and have significant influence on their environments. SMBHs cannot be observed directly but are studied through phenomena such as tidal disruption events (TDEs). A TDE occurs when a star is torn apart by the immense gravitational forces of an SMBH, forming an accretion disk with transient electromagnetic radiation. This study analyzes photometric properties of galaxies with observed radio emission from TDEs, comparing them to a control sample of 500 redshift-matched galaxies from the Sloan Digital Sky Survey. Galaxies hosting radio TDEs exhibit significantly lower g − r color (∼0.135 mag), consistent with more active star-forming populations. W1 − W2 values show no significant difference, suggesting dust content does not distinguish TDE hosts and that emissions from dust-rich galaxies may be undercounted. Although photometric analysis alone may not identify TDEs, it can guide follow-up observations by highlighting promising host galaxies.

Keywords: Supermassive black holes, Tidal disruption, Radio astronomy
An Ultra-hot Low-mass Brown Dwarf Eclipsing the Puffy White Dwarf J0404+1112. Most exoplanets known orbit stars that will evolve into red giants, then white dwarfs (WDs). Understanding the population of substellar WD companions informs the common-envelope evolution process (E. Villaver &amp; M. Livio 2009), thereby shedding light on the current and future planetary population of the Milky Way. Here, we report the discovery of a low-mass (25 ± 5MJup) brown dwarf (BD) fully eclipsing every 2.93 hr the WD J0404+1112, which we found to be an unexpectedly large host WD (2REarth). The eclipsing nature of the system, the low masses of the primary (∼0.3MSun) and secondary, and the large day─night temperature contrast for the BD ( ⪭ 2000 K) make it a prime target amongst the dozen WD+BD systems known for a detailed study via JWST phase-curve observations.

Keywords: Eclipsing binary stars, White dwarf stars, Brown dwarfs
Photometric Constraints on Activity of Centaur 174P/Echeclus from 2021 Through 2024. We present results from an observing campaign focused on monitoring the dust coma of centaur 174P/Echeclus using the 8.1 m Gemini North and South telescopes. Six epochs of imaging data were acquired from 2021 November through 2024 February. No conspicuous dust coma was detected in the imaging data. The images were used for upper-limit dust production rate estimates, nucleus color measurements, and nucleus size estimates. The weighted mean nucleus colors are  (g'−r')=0.64±0.03  and  (r'−i')=0.27±0.03 , where the uncertainties provided are the standard deviations of the individual color measurements. The colors are consistent with the gray/neutral centaur population and indicate no appreciable color evolution or rotational variation observed. We estimate the effective nucleus diameter to be 66.8 ± 2.0 km, which is consistent with previous reports, further supporting the assessment of no dust coma being present.

Keywords: Centaur group, Planetary science
Polarimetric Variability Hints at Long-term Structural Changes in CV Ser. Wolf─Rayet binaries that produce carbonaceous dust are important contributors to the Galactic dust budget. The short-period WCd binary CV Serpentis represents an understudied orbital geometry for dust production; it is unclear whether CV Ser's dust is formed within the circular binary orbit or whether it probes a larger-scale system architecture. We present new polarimetric data on CV Ser, consisting of two data sets spanning the 30 days period but separated by 30 yr. We find that since 1987, both the magnitude and the orientation of the polarization have changed. Because this polarization is caused by light scattering in ionized gas and/or dust in the system, these changes may reflect a long-term variation in its circumstellar structure, such as a long-period wind interaction or the formation of massive dust clumps.

Keywords: Wolf-Rayet stars, Circumstellar dust, Binary stars, Spectropolarimetry
Can Lava Lakes from Planetary Debris form on Low-mass M Dwarfs?. A recent Research Note observes that late-type M dwarf average densities are two orders of magnitude higher than that of lava, and suggests that planetary debris from tidal disruption events (TDEs) could form long-lived and potentially detectable lava lakes on the surfaces of cool M dwarfs. This would represent a very valuable observational avenue for studying TDEs and any other mechanisms that might give rise to planetary engulfment on cool dwarfs. However, examining the density structure of low-mass M dwarfs reveals that lava would only become buoyant at depths well below photospheric, and where plasma temperatures are of the order of 105 K. Infalling lava would be rapidly evaporated on timescales of hours, but could form evanescent and detectable metal-enhanced regions with lifetimes of the order of the surface convective turnover time of a day or so.

Keywords: M dwarf stars, Stellar structures, Tidal disruption, Exoplanet systems, Interstellar objects, Exoplanet detection methods, Stellar atmospheres
A (Very) Simple Proof of the Gravitational Energy Formula of Polytropic Spheres. Ii is shown how the well-known formula for the gravitational energy of self-gravitating regular polytropes of finite mass can be obtained in an elementary way by using Gauss's divergence theorem and the Chandrasekhar virial tensor, without resorting to lengthy algebra, to specific properties of Lane─Emden functions, and to thermodynamics arguments, as is instead commonly found in standard treatises and in astrophysical literature. The present approach, due to its simplicity, can be particularly useful to students and researchers, and it can be easily applied to the study of more complicated polytropic structures.

Keywords: Stellar physics, Polytropes, Stellar dynamics, Newtonian gravitation
An In-depth Study of Brown Dwarfs with TESS. The existence of a deficit of brown dwarfs (BDs) in close orbit around main-sequence stars is one of the most intriguing questions in stellar physics. This so-called BD desert may result from the transition between two different dominant formation processes occurring for different mass regimes. While the BD mass derived from radial-velocity measurements helps confirm the nature of the analyzed objects, the BD radius obtained from transits is important to better constrain the BD age, as BDs are believed to contract with age. Such objects with well-constrained parameters, although in small number, are of prime interest for deeper investigations of BD structure and chemical composition. The present document aims at presenting the first results of a search for BD transits among a sample of approximately 3300 host star candidates observed by the Transiting Exoplanet Survey Satellite during Cycle 6.

Keywords: Transit photometry, Brown dwarfs
Prospects for the Crossing of Comet 3I/ATLAS's Ion Tail. During 2025 October─November, interstellar comet 3I/ATLAS, will pass upstream of the Europa Clipper and Hera spacecraft. Here, we identify two potential opportunities for in situ observations of 3I's ion tail by immersion, facilitated by the close alignment between the comet's hyperbolic trajectory with the ecliptic plane. During the period 2025 October 30─November 6, it is predicted that Europa Clipper will potentially be immersed within the ion tail of 3I/ATLAS, providing the opportunity to detect the signatures of an interstellar comet's ion tail. Characteristic changes to the solar wind are also expected to be observed; a magnetic draping structure associated with the comet may be identifiable. It is further predicted that spacecraft Hera will possibly be immersed within the ion tail of 3I/ATLAS during the period 2025 October 25─November 1.

Keywords: Comet ion tails, Space probes, Solar wind, Long period comets, Interstellar objects