Sazuna/UAT_keywords huggingface dataset:
Variability Census of Legacy Catalogs. IV. 3600+ New δ Scuti and γ Doradus Stars. This study identifies over 1490 new δ Scuti and 2206 new γ Doradus stars. These discoveries result from the fourth phase of a variability census of A-F stars in the HD and SAO catalogs, excluding those cross-matched with the PPM catalog. Across four project phases, I have checked the Transiting Exoplanet Survey Satellite (TESS) light curves for 110,152 A-F stars selected from PPM, HD, and SAO catalogs. This comprehensive survey has now identified over 11,180 δ Scuti, 9886 γ Doradus, and 1342 eclipsing binaries, along with thousands of other variable types. Notably, over 2712 of these variables exhibit hybrid δ Sct-γ Dor pulsations, and more than 198 eclipsing binaries contain pulsating (δ Sct or γ Dor) primary components. Using TESS data, this work has revealed a significant population of previously undetected variable stars, essential for stellar and asteroseismic studies due to their relatively bright nature.

Keywords: Eclipsing binary stars, Gamma Doradus variable stars, Delta Scuti variable stars, Pulsating variable stars
Discovery of 128 New Saturnian Irregular Moons. We highlight the announcement by the IAU Minor Planet Center of 128 new irregular moons of Saturn discovered in our CFHT imaging acquired in 2023. We were able to link 83 of the new moons to detections from our earlier 2019–2021 study. Of the 58 new retrograde moons with multiyear arcs, 46 are likely in the Mundilfari subgroup. This large fraction is in line with the steep size distribution of the subgroup and the idea that it was created by a recent collision. Also, by more than tripling the number of Kiviuq subgroup members, the new discoveries have confirmed that this subgroup is a very tightly grouped collisional family, although likely much older.

Keywords: Irregular satellites, Saturnian satellites, Natural satellites (Solar system)
"Dark Comet" 2005 VL<SUB>1</SUB> is Unlikely to be the Lost Soviet-era Probe Venera 2. A. Loeb &amp; R. Cloete intriguingly suggest that the near-Earth object 2005 VL1 could be the lost Soviet probe Venera 2. Here I evaluate the plausibility of such a claim against the available data. I have re-determined the orbit of 2005 VL1 (including a non-gravitational acceleration component) using the astrometric observations retrieved from the Minor Planet Center database. By propagating the orbit of 2005 VL1 over the period of the Venera 2 mission, I compare this object's distance from the Earth and from Venus at the times of the probe's launch and flyby with Venus, respectively. My analysis, which takes into account realistic uncertainties on both the orbit of 2005 VL1 and the position of Venera 2, decisively rules out the proposed identification. My approach relies entirely on open-source software and publicly available data, and could represent a viable method to assess similar claims in the future.

Keywords: Astrodynamics, Near-Earth objects, Orbit determination, Planetary probes
Could (355256) 2007 KN<SUB>4</SUB> Become a Large Potentially Hazardous Asteroid?. The connection between Near-Earth asteroids and the main belt is well established, yet few concrete examples exist of asteroids that are migrating between the two regions. (355256) 2007 KN4 presents a compelling case, as it may evolve first into a main belt asteroid, and then a potentially hazardous asteroid within a few tens of thousands of years. As it is approaching its best apparition in decades, observations of this asteroid are encouraged.

Keywords: Amor group, Near-Earth objects, Kirkwood gaps, Orbital resonances, Apollo group
IAU CPS Satellite Optical Brightness Recommendation: Rationale. In this Note, we discuss the rationale behind the IAU CPS's recommendation on satellite brightness for objects in low Earth orbit (LEO). Specifically, we clarify the reasoning behind the chosen altitude dependence and the limitations of this choice. We further discuss some approaches toward brightness limits for objects beyond LEO. This Note is intended for both astronomers and satellite operators in the spirit of furthering mutual cooperation.

Keywords: Artificial satellites, Light pollution
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å in Late B-type Stars. XVII. HD 49606 (33 Gem). The weak line of Hg II located at 5677.10 Å is detected as a 1% absorption feature in ESPaDOnS spectra of the HgMn star HD 49606. The synthesis of this Hg II feature yields a mercury excess, about +4.30 dex which is about the same than the excess derived from the Hg II line at 3983.93 Å. There is no evidence for variability of this line in the I profiles used in this work. The abundances of helium, magnesium, silicon, titanium, chromium, manganese, iron derived from the synthesis of the 4400–4600 Å spectral interval agree well with previous determinations.

Keywords: Mercury-manganese stars, Chemically peculiar stars
Prediction and Observation of a Stellar Occultation by Haumea's Satellite Namaka. Stellar occultations are an ideal way to characterize the physical and orbital properties of trans-Neptunian binary systems. In this research note, we detail the prediction and observation of a stellar occultation observed with NASA's Infrared Telescope Facility on 2025 March 16th (UT), with drop-outs from both the dwarf planet Haumea and its smaller satellite Namaka. This occultation places a lower limit of 83 ± 2 km on Namaka's diameter. We also discuss the possibility that this detection could help to constrain the orbit of Namaka, measure Haumea's gravitational harmonics, and provide a path to measuring the internal structure of Haumea.

Keywords: Dwarf planets, Natural satellites (Solar system), Stellar occultation, Trans-Neptunian objects
NEIDSpecMatch: Stellar Parameter Estimation with NEID Spectra Using an Empirical Library. We introduce NEIDSpecMatch, a tool developed to extract stellar parameters from spectra obtained with the NEID spectrograph. NEIDSpecMatch is based on SpecMatch-Emp and HPFSpecMatch, which estimate stellar parameters by comparing the observed spectrum to well-characterized library spectra. This approach has proven effective for M dwarfs. Utilizing a library of 78 stellar spectra covering effective temperatures from 3000–6000 K, NEIDSpecMatch derives key parameters, including effective temperature, metallicity, surface gravity, and projected rotational velocity. Cross-validation shows median uncertainties of  , σ[Fe/H] = 0.143, and   across 49 orders. We showcase its application by fitting the spectrum of an M-dwarf and discuss its utility across a wide range of spectra observed with NEID. NEIDSpecMatch is pip-installable.

Keywords: Astronomical instrumentation, Stellar properties, Spectroscopy
Origin of the System of Globular Clusters in the Milky Way—Gaia eDR3 Edition. In this research note I update the associations between globular clusters and their putative galaxy progenitors determined in D. Massari et al., based on the kinematic measurements from the Gaia early data release 3 (eDR3). The table with the associations is available at https://www.oas.inaf.it/en/research/m2-en/carma-en/, and will be kept up-to-date whenever improved data become available. The same table will also provide updated age estimates from the CARMA project. Please cite this Note alongside Massari, Koppelman &amp; Helmi 2019, eDR3 edition.

Keywords: Globular star clusters, Milky Way evolution, Milky Way dynamics
Association of 220 PeV Neutrino KM3-230213A with Gamma-Ray Bursts. Recently, the KM3NeT Collaboration announced the detection of a 220 PeV neutrino from the celestial coordinates R.A. = 94 3 and decl. = ‑7 8 on 2023 February 13 at 01:16:47 UTC. The source for this extra-ordinary cosmic neutrino, designated KM3-230213A, is not identified yet but there has been speculation that it might be associated with a gamma-ray burst GRB 090401B. The purpose of this report is to search the association of this 220 PeV neutrino with potential GRB sources from a more general consideration of Lorentz invariance violation (LV) without predefined LV scale. We try to associate this extra-ordinary neutrino with potential GRBs within angular separation of 1°, 3° and 5° respectively and the results are listed in Table 1. We find the constraints ELV ≤ 5.3 × 1018 GeV for subluminal LV violation and ELV ≤ 5.6 × 1019 GeV for superluminal LV violation if KM3-230213A is a GRB neutrino.

Keywords: Particle astrophysics, Burst astrophysics, Neutrino astronomy, High energy astrophysics
The Corona in the Quiet Sun: A Global Substrate Driven by Velocity Filtration?. EUV coronal images are usually dominated by emission from magnetic active regions and from flares: the magnetic fields generate prominent spatial structures ("loops") and striking time-dependent behavior. However, the quiet Sun contains regions, covering significant fractions of the solar surface, where evidence for spatial structure or time-dependence is weak or absent. J. D. Scudder suggested that velocity filtration might explain the presence of hot coronal gas without relying on magnetic fields, and without the "deposition" of energy in the corona. Such a process could lead to a coronal component which is essentially independent of the solar cycle. I suggest that the quiet Sun corona is a candidate for a global substrate created by velocity filtration.

Keywords: Solar cycle, Quiet sun, Quiet solar corona
Observations and Characterization of the New Active Centaur 2023 RS<SUB>61</SUB>. We report the cometary activity of the Centaur 2023 RS61 (RS61) evident in our UT 2025 January 2 observations with the Lowell Discovery Telescope, showing a coma and a ∼5 9-long tail. The archival observations from the Pan-STARRS1 survey reveal two previously unnoticed activity episodes in 2017 and 2023, suggesting SR61 could be a rare outbursting Centaur similar to 174P/Echeclus. The outburst on UT 2017 October 10 at rH = 13.5 au makes RS61 the second-most distant active Centaur after 95P/Chiron. We estimate a nucleus size between 4.7 km ≤ rn ≤ 7.0 km, assuming typical Centaur geometric albedos, an upper-limit Afρ ≤ 245 cm and dust production rate   kg s‑1. As RS61 approaches the perihelion in 2028 its activity will likely increase, making this object an exciting observing target.

Keywords: Short period comets, Centaur group
Apparent Change in Comet 103P/Hartley 2's Rotation Period During 2023/2024 Measured via Aperture Photometry. A photometric study of Comet 103P/Hartley 2 is presented, aiming at the detection and analysis of rotationally induced variability during its latest apparition 2023/2024. Brightness measurements within a 5000 km radius aperture using a green filtered spectral range reveal periodic variations, despite the use of different instrumentation, non-standard filters, and varying observing conditions. An increase of the rotation period from 18.6 to 19.1 hr within about 4 months was found, a slowing-down of the rotation similar to results from the apparition in 2010.

Keywords: CCD photometry, Short period comets, Comets
Edward S. Holden and the Bands of Neptune. Reports of visual sightings of bands on Neptune made by E. S. Holden and J. M. Schaeberle at Lick Observatory are described. Holden's logbooks record that in 1888 September and October bands were discerned on the Neptunian disk and noted on seven nights. A summary of the logbook entries are given in this note, since they do not appear to have been previously published.

Keywords: Neptune, History of astronomy
JWST Observations of Potentially Hazardous Asteroid 2024 YR4. The destructive power of an impacting asteroid is primarily estimated by knowledge of its size. Asteroid 2024 YR4 reached a peak 2032 impact probability with Earth of 3%, motivating a desire to determine its size. Owing to its infrared capabilities, JWST is uniquely suited for such assessment, especially for decameter-scale objects. We used JWST to observe 2024 YR4 and find a diameter of 60 ± 7 m. This size range corresponds to an albedo for 2024 YR4 of 8%–18%, consistent with observation that it is an S-type asteroid (International Asteroid Warning Network, https://iawn.net/obscamp/2024YR4/index.shtml), if at the low-albedo end of that asteroid taxon. Future observations through 2025 May will help further refine the asteroid's thermophysical model.

Keywords: Near-Earth objects, Asteroids, Infrared photometry
Hidden Companions to Intermediate-mass Stars. XXVI. Uncovering Nunki = Sigma Sagittarii as a 6.5 M<SUB>⊙</SUB> + 6.3 M<SUB>⊙</SUB>, 0.60 au Binary. Nunki = Sigma Sagittarii is a nearby B2.5V star and the 51st visually brightest star in the night sky. There is some contradiction in the literature on whether it is single or a close binary and also on the nature of the possible companion. Here we report on a VLTI/GRAVITY observation which revealed that σ Sgr does indeed have a close companion with a K band flux ratio of 87.72% at a projected separation ρ = 8.644 mas ↔ 0.60 au. We estimate isochrone masses MAa ≃ 6.5M⊙ and MAb ≃ 6.3M⊙ and a system age of 30 Myr. The stars will most likely merge in about 20 Myr, so that Nunki is not only the most massive system within 70 pc but also the closest core-collapse supernova progenitor at the moment, edging Spica by at least a few parsec. *Based on observations collected at the European Southern Observatory, Chile, Program ID 113.26GM.001.

Keywords: Optical interferometry, Multiple stars, B stars
Deriving Stellar Parameters for High-redshift (1.2 ≤ z ≤ 2.6) Galaxies Using CIGALE. We present results for 19 galaxies in the redshift range 1.2 ≲ z ≲ 2.6 to model star formation rate (SFR) and stellar mass using galactic spectral energy distributions. With W. M. Keck Observatory MOSFIRE we spectroscopically confirm redshifts using lines of Hα, which are further used to confirm SFR and stellar mass calculations. Our observed and modeled SFRs are in reasonable agreement, validating the modeled parameters produced by the application of Code Investigating GALaxy Emission stellar population synthesis software to Keck MOSFIRE observations of high-redshift galaxies.

Keywords: Astronomy data modeling, High-redshift galaxies, Astronomy data analysis
Hidden Transits: TOI-2285 b is a Warmer Sub-Neptune Likely with a Super-Earth Companion. TOI-2285 b is a sub-Neptune-sized planet orbiting a nearby M dwarf, discovered through the TESS photometric survey and ground-based follow-up observations. The planet was initially reported to have an orbital period of 27.27 days, making it one of the lowest temperature sub-Neptunes transiting a bright M dwarf. However, additional TESS data reveal that its true orbital period is 13.64 days, half the original value, resulting in a warmer equilibrium temperature (358 K) than previously estimated (284 K). The misidentification likely resulted from the low signal-to-noise ratio of individual transit signals and the limited number of transits observed by TESS at that time. This case highlights the importance of carefully considering harmonic solutions for similar cases. The additional TESS data also reveal another planetary candidate with an orbital period of 9.67 days and a radius of 1.5 R⊕, requiring validation in future studies.

Keywords: Mini Neptunes, Transit photometry, Exoplanet systems
Stellar Parameters for over 50 Million Stars from SMSS DR4 and Gaia DR3. We present an updated catalog of stellar parameters, including effective temperature, luminosity classification, and metallicity, for over fifty million stars from the SkyMapper Southern Survey (SMSS) DR4 and Gaia DR3. The accuracy of the derived parameters remains consistent with those achieved with SMSS DR2 using the same methods. Thanks to the advancements in SMSS DR4, photometric-metallicity estimates are now available for an unprecedented number of metal-poor stars. The catalog includes over 13 million metal-poor ([Fe/H] ≤ ‑1) stars, nearly three million very metal-poor ([Fe/H] ≤ ‑2.0) stars, and approximately 120,000 extremely metal-poor ([Fe/H] ≤ ‑3.0) stars—representing an increase by a factor of 4–6 compared to SMSS DR2. This catalog, combined with other stellar parameters obtained through our efforts, will be made available at the China-VO and Zenodo.

Keywords: Fundamental parameters of stars, Metallicity, Sky surveys
On the Prevalence of Early Mass Transfer for Very Massive Binaries. Common phases of mass transfer in massive stellar binaries are case A (during the donor's main sequence) and case B (after the donor's main sequence but before helium core depletion). Most stars see their radii significantly grow after the main sequence, making case B more common. However, very massive stars may already undergo significant expansion during the main sequence increasing the probability of case A mass transfer. We find that using convective boundary mixing informed by the width of the main sequence in 30 Doradus, case A mass transfer dominates for donor masses ≳75 M⊙. This is not the case without convective boundary mixing or in the stellar models commonly used in rapid binary population synthesis. Therefore, case A mass transfer may be more dominant than commonly assumed, with potential impact on rates of all post mass transfer binaries, from Wolf–Rayet-O-type binaries, to X-ray binaries and gravitational wave progenitors.

Keywords: Massive stars, Binary stars, Stellar mass black holes, Stellar convective zones
Floaters on the Surfaces of Red Dwarfs. The tidal disruption of a rocky planet by a red dwarf results in a stream of molten rock, with half the material eventually landing on the surface of the star. Since the mean density of a ∼0.1M⊙ star is ∼102 g cm‑3, the rocky debris with a density of ∼3 g cm‑3 would lead to lava rivers or lakes floating on the surface of the red dwarf. These would be observable as stellar spots, owing to their high opacity. Advanced technological civilizations could design ships that float on the surface of red dwarfs and constitute a new type of technological signatures.

Keywords: Dwarf stars
Notes on Compact Obscured Nuclei. I. The Evolutionary Context. Luminosity sources in compact obscured nuclei (CONs) and the role of CONs in galaxy evolution are yet to be fully understood. We address these through an examination of luminosity and mass distributions of a sample of CONs in luminous infrared galaxies (CON-LIRGs), Compton thick active galactic nuclei (CT-AGN), and luminous infrared galaxies (LIRGs). We find LIRGs, CON-LIRGs, and CT-AGN occur in disk galaxies with similar stellar masses. CON-LIRGs and LIRGs, while potentially powered in different ways, have similar bolometric luminosities. Since these three unusual evolutionary phases occur in the same general population of galaxies, transitions between these evolutionary phases are possible within the same galaxy. However, CONs typically are substantially more luminous than CT-AGN, so evolution from a CT-AGN to a CON-LIRG would require additional luminosity from a compact starburst or increased central black hole accretion power. CON-LIRGs are not simply more deeply embedded versions of CT-AGNs.

Keywords: Galaxy environments, Galaxy nuclei, Active galactic nuclei, Luminous infrared galaxies
Super-SNID: An Expanded Set of SNID Classes and Templates for the New Era of Wide-field Surveys. We present an expanded template library for the supernova identification (SNID) software, along with updated source files that make it easy to merge our templates—and other major SNID libraries—into the base code. This expansion, dubbed "Super-SNID," increases the number of spectra for under-represented supernova classes (e.g., SNe Ia-02cx, Ibn) and adds new classes (e.g., SLSNe, TDEs, LFBOTs). Super-SNID includes 841 spectral templates for 161 objects, primarily from the Public ESO Spectroscopic Survey of Transient Objects Data Releases 1–4. The library is available on GitHub with simple installation instructions.

Keywords: Astronomical techniques, Transient sources, Classification
Dinner with a Star: Stellar Engulfment of Exoplanet Systems. As a star evolves, its radius expands and can surpass the semimajor axis of an orbiting planet in a planetary engulfment event. In this project, we obtain time-dependent radius values for various stellar masses using Modules for Experiments in Stellar Astrophysics and compare the results to known exoplanet systems to predict if/when host stars will swallow their planets, assuming no further dynamical evolution of the systems. Our models predict that 61% of exoplanets are planetary engulfment candidates, with most events occurring just before the onset of helium fusion, near the first dredge-up. This finding suggests that resulting stellar lithium enrichment may be quickly erased, leaving enhanced angular momentum as a more reliable tracer for engulfment. We also find an inverse correlation between the mass of the host star and the probability of planetary engulfment.

Keywords: Exoplanets, Stellar evolution
Sub-parsec Detectability Lifetimes for a Sample of Dual AGN with Known Mass Ratios. We analyze 84 double quasars from the Sloan Digital Sky Survey, selected by G. Foreman et al., to investigate the sub-parsec-scale detectability lifetimes of supermassive black hole (SMBH) binaries—key progenitors of low-frequency gravitational waves. We compute the time during which binaries with the same mass ratios as the G. Foreman et al. sample are likely to have observable signatures in variable broad line profiles. Our results are helpful for predicting the population of resolvable SMBH binaries detectable with future space-based interferometers such as the Laser Interferometer Space Antenna.

Keywords: Double quasars, Supermassive black holes, Galaxy mergers
Transit-APP: A Centroid-free Method of Identifying Background Transit False Positives. We present a centroid-free method to identify which star is the source of a known transit signal from pixel data. This method is based on observed and simulated difference images, and provides a relative probability of a star being the source of the transit compared to other known stars. This method is robust at low S/N compared to common centroid-based methods, and is well suited for space-based transit surveys such as Kepler and TESS.

Keywords: Surveys, Exoplanets
Compact Obscured Nuclei. II. Chaotic Central Dust Structures in NGC 4418. Compact Obscured Nuclei (CONs) are rare types of galactic nuclei obscured by dense, dusty molecular gas. Dusty structures extending beyond hidden CONs produce observable absorption features revealing connections between CONs and their environments. We analyzed central dust features in the CON galaxy NGC 4418, a Luminous Infrared Galaxy using Hubble Space Telescope images. We mapped dust absorption features, calculated optical depths, and derived limits on associated gas masses from color-ratio images. We find NGC 4418 contains complex, three-dimensional spatially resolved dust structures near its CON having τV ≈ 2–3. This medium is a candidate for the foreground responsible for the deep mid-infrared silicate absorption toward the CON. Our map of the inner dust structures agrees with molecular studies in suggesting the complex structure of the central molecular gas NGC 4418 reflects the ongoing interaction with its companion and the wind from the CON.

Keywords: Galaxy interactions, Interstellar medium, Luminous infrared galaxies
Collimation of Fast Radio Burster 20201124A. The recent discovery of a period in the active repeating Fast Radio Burster 20201124A and measurement of its spindown rate place bounds on the solid angle of its emission on the basis of an energetic argument. The bound depends on the (unknown) efficiency of conversion of rotational energy to coherent radio emission and implies a lower bound on the Lorentz factor of the radiating charges.

Keywords: Magnetars