Sazuna/UAT_keywords huggingface dataset:
A Change of the Rotation Period of Asteroid (65803) Didymos Caused by the DART Impact. On 2022 September 26, the NASA Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the secondary component of the binary asteroid (65803) Didymos. This experiment tested the kinetic impactor technology for diverting dangerous asteroids. Due to the impact, the binary system's angular momentum has changed, resulting in a significant change in the orbital period of Dimorphos. Precise values of the pre- and postimpact orbital periods were derived from a large set of photometric light curves measured for the Didymos─Dimorphos system during six apparitions from 2003 to 2023. We used these data to detect a possible change in the rotation period of the primary as a consequence of the impact. We analyzed the binary system's light curves using the binary asteroid light-curve decomposition method. We selected parts of the light curves covering orbital phases outside mutual events, which represent the primary rotational light curves. We applied the light-curve inversion method to construct a convex shape model of Didymos and determine its rotation period before and after the impact. These two periods were treated as independent free parameters of the modeling. We found a value of 2.260 389 1 ± 0.000 000 2 hr for the preimpact period and 2.260 440 ± 0.000 008 hr for the postimpact period. Their difference 0.18 ± 0.03 s is small yet significant, indicating that the rotation of Didymos became slower after the DART impact. The most plausible physical explanation is Didymos's postimpact reshaping, making its shape more oblate.

Keywords: Small Solar System bodies, Asteroid satellites, Asteroids
A Catalogue of Interstellar Material Delivery from Nearby Debris Disks. We modeled the trajectories of material ejected from 20 nearby debris disk stars, including ϵ Eridani (Ran), Vega, Fomalhaut, and β Pictoris, within a simulated Milky Way potential in order to quantify their contribution to the population of interstellar material entering the solar system. Our simulations show that material from each of these 20 systems is currently to be expected within our planetary system. We calculate expected fluxes of both macroscopic interstellar objects (ISOs, ≥100 m), which could be detected by telescopic surveys, and smaller meteoroids (≥200 μm), which could manifest as meteors in Earth's atmosphere. We estimate that the ISO population originating from these debris disks and currently within the inner solar system is on the order of ∼2, only a fraction of the expected total ISO population but nonetheless likely to be discovered by Rubin. Meteors in Earth's atmosphere from these systems are expected as well, but current methods, both radar and video, might require decades to collect even a single event. Our sample is found to be rich in relatively low excess velocity particles compared to the broader expected ISO population, which might make them harder to distinguish observationally from bound objects in some cases. These results provide a framework for linking detections of interstellar material to their astrophysical origins, offering new opportunities to probe the composition and dynamical history of nearby planetary systems.

Keywords: Meteor streams, Meteor radiants, Interstellar dynamics, Interstellar objects
Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 3 → 4. XXIV. Discovery of a 0.70 M<SUB>⊙</SUB>, 0.06 au Companion to Upsilon Ophiuchi Ab (Plus Discovery of the υ Oph Mini-cluster). Upsilon Ophiuchi is a nearby 30 au visual binary. The primary (Aa) is a known close spectroscopic binary. Here we report on a VLTI/GRAVITY interferometric observation which revealed that the visual secondary (Ab) is also a close binary (ρ = 1.5 mas ↔ 0.06 au). The primary was also spatially resolved as a ρ = 10.90 mas binary, confirming υ Oph as a 2+2 quadruple. We estimate masses MAa1 = 1.83M⊙, MAa2 = 1.47M⊙, MAb1 = 0.82M⊙and MAb2 = 0.70M⊙and a system age of 50 Myr. We find that there are six stars within 5° ↔ 3.5 pc of υ Oph that share parallaxes and proper motions with it, suggesting that they form a mini-cluster of only about 8M⊙ in total mass. *Based on observations collected at the European Southern Observatory, Chile, Program ID 105.D-0647(B).

Keywords: Optical interferometry, Multiple stars, A stars, Star clusters
The Radial Extent of [O III] Outflows in AGN. In this report, we examine the radial and total extents of ionized gas in a sample of 23 Seyfert galaxies from the Swift-BAT Active Galactic Nuclei (AGN) sample. We compare the radial extent of the ionized outflow to the AGN power measured by X-ray luminosity and total [O III] luminosity, for comparison to a previous study that measured only the total, rather than radial, extent of the ionized gas and did not consider X-ray luminosity. We find that the radial size does not provide a tighter relationship with either measure of AGN luminosity. We also find that the X-ray luminosity is slightly better correlated with ionized gas extent than total [O III] luminosity, but with high uncertainty. Type 1 AGN tend to have less scatter in these relationships than Type 2 AGN, as expected.

Keywords: AGN host galaxies, Active galaxies, Active galactic nuclei
AI-enhanced Citizen Science Discovers Cometary Activity on Near-Earth Object (523822) 2012 DG61. We report the discovery of cometary activity in the form of a pronounced tail emanating from Near-Earth Object (523822) 2012 DG61, identified in UT 2024 April 18 Dark Energy Camera images by our AI assistant TailNet. TailNet is an AI designed to filter out images unlikely to show activity for volunteers of our NASA Partner "Active Asteroids" Citizen Science campaign, from which our AI is trained. Subsequently, our archival investigation revealed 2012 DG61 is recurrently active after we found it displaying a pronounced tail in a UT 2018 April 16 Steward Observatory Bart Bok 2.3 m telescope image and UT 2018 May 14 observations by G. Borisov with the 0.3 m telescope at MARGO Observatory. Our dynamical integrations reveal that 2012 DG61, an Apollo dynamical class member, is likely in 2:1 mean-motion resonance with Jupiter. We encourage additional observations to help characterize the activity morphology of this near-Earth comet.

Keywords: Near-Earth objects, Asteroids, Comae, Comet tails, Convolutional neural networks
Convection Speeds in Lower Main-sequence Stars: Why is There a Plateau in Mid-K Dwarfs?. Convection in cool stars (Teff &lt; 6500 K) occurs when hotter, rarefied gas is accelerated up by buoyancy, and cooler, denser gas accelerated down. Observers have reported how convective speed vc varies with height and with Teff. Cool-star convection typically starts in the photosphere (τc ≈ 1), with overlying layers mainly radiative: this convection originates in atomic hydrogen ionization, and vc is predicted to decrease monotonically as Teff decreases. Studies of vc in K and M stars have revealed unexpected results: as Teff decreases, vc in late-K dwarfs exhibits a plateau, while in late-K giants, there is no plateau. Independent evidence from broad-band photometry of late-K dwarfs has suggested that a distinct convection zone operates high in the atmosphere of such stars, driven by molecular hydrogen H2. I suggest that the behavior of vc in late-K dwarfs may be associated with onset of H2-driven convection in the upper atmosphere.

Keywords: Broad band photometry, K stars, Molecular data, Stellar convective zones
An Updated Detection Pipeline for Precursor Emission in Type II Supernova 2020tlf. We present a new photometric pipeline for the detection of pre-supernova (pre-SN) emission in the Young Supernova Experiment (YSE) sky survey. The method described is applied to SN 2020tlf, a type II SN with precursor emission in the last ~100 days before first light. We re-analyze the YSE griz-band light curves of SN 2020tlf and provide revised pre-explosion photometry that includes a robust list of confident detection and limiting magnitudes. Compared to the results of W. V. Jacobson-Galán et al., this new analysis yields fewer total r/i/z-band pre-SN detections at phases &gt;‑100 days. Furthermore, we discourage the use of the blackbody modeling of the pre-explosion spectral energy distribution, the pre-SN bolometric light curve and the blackbody model parameters presented in W. V. Jacobson-Galán et al. Nevertheless, binned photometry of SN 2020tlf confirms a consistent progenitor luminosity of ~1040 erg s‑1 before explosion.

Keywords: Sky surveys, Supernovae
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å in Late B-type Stars. XIII. HR 6000 (HD 144667). The weak line of Hg II located at 5677.10 Å is not detected in Ultraviolet and Visible Echelle Spectrograph spectra of the Chemically Peculiar star HR 6000. This is explained by the very low mercury excess in this young late B-type star. The synthesis of various spectral intervals yields several new measurements of the abundances of helium, carbon, oxygen, magnesium, aluminium, silicon, phosphorus, titanium, chromium, manganese, iron, nickel, gallium, yttrium and xenon. Helium is found to be very depleted by ‑2.0 dex, most of the other measurements agree with the abundances previously published. An examination of the Transiting Exoplanet Survey Satellite light curves of HR 6000 shows that the optical flux is variable on timescales of days but no clear periodicity is visible.

Keywords: Helium-weak stars, Chemically peculiar stars
A Report from Madrid (Spain) on the Total Solar Eclipse of 1842 July 8. The total solar eclipse of 1842 July 8, observed from Madrid, was documented by Gerónimo del Campo, interim director of the Madrid Observatory. Published in the "Gaceta de Madrid," the report describes a luminous corona aligned with the Sun's center, appearing at totality and disappearing seconds later. The corona displayed pinkish tones, iridescence, and divergent rays. Additional phenomena included a bluish-livid sky, visible stars (Capella and Aldebaran), and Baily's beads, all observed through tinted glasses.

Keywords: Total eclipses
V442 Cen: Is the Accreting White Dwarf Ultra-rapidly Rotating?. As observed with the Hubble Space Telescope, the archival Space Telescope Imaging Spectrograph far-ultraviolet spectrum of the white dwarf (WD) in the dwarf nova V442 Cen reveals no photospheric absorption features from accreted metals, despite its WD accounting for 100% of the UV light in quiescence. We discuss why V442 Cen does not exhibit any metals in its photosphere, including the possibility that its rotational velocity is so rapid that it smears out the absorption lines of accreted metals. In this case, the accreting WD in V442 Cen would be the most rapidly rotating non-magnetic CV WD.

Keywords: White dwarf stars
A Neptune-size Planet Candidate in a 2.77 days Orbit Around TYC 8996-1013-1?. We report the detection of repeated transits in the TESS light curves of TYC 8996-1013-1 (TIC 414929408) with a period of 2.77542 ± 0.00001 days and a width of 4.32 hr. We did not find significant variability in the transit time through the observations taken during TESS Sectors 37, 38, 64 and 65. The color B ‑ V and the GAIA DR3 spectrum of TYC 8996-1013-1 point to a stellar temperature of ≈5000 K and radius of ≈1 R⊙, and thus the transit model suggests a Neptune size for the candidate transiting planet (radius ≈ 25,000 km).

Keywords: Transits, Exoplanets
The Variable X-Ray Emission of the Cataclysmic Variable V1460 Her with a Rapidly Rotating White Dwarf. Using a recent Chandra ACIS observation of the eclipsing cataclysmic variable (CV) V1460 Her (2MASS J16211735+4412541) with a fast-rotating (Pspin = 38.9 s) white dwarf, we estimated a flux   erg cm‑2 s‑1, a factor of ~7 lower than found from previous Swift XRT observations ≈8 yr ago, when the CV was quiescent. The drop in the flux suggests a corresponding drop in the accretion rate, and the resulting intrinsic luminosity L0.5–7 keV ~ 1.6 × 1029 erg s‑1 places V1460 Her among the lowest-luminosity magnetic CVs known, in a state of very low accretion.

Keywords: Eclipsing binary stars, White dwarf stars, Cataclysmic variable stars
New TESS Secondary Eclipses Confirm Orbital Decay of Kepler-1658b. I present new primary and secondary eclipse timing measurements for the hot Jupiter Kepler-1658b from TESS Sectors 74, 75, 81, and 82. Joint analysis of these measurements with historical Kepler data and radial velocity observations confirms orbital decay with rate   s day‑1. The detection of secondary eclipses in TESS data provides independent confirmation of decay over precession models (BIC = ‑ 364.3,  ), yielding a stellar tidal quality factor  . These measurements strengthen the case for rapid tidal inspiral in this evolved system.

Keywords: Exoplanets, Transit timing variation method, Hot Jupiters
Exploring Spica's Apsidal Motion: Insights from Feature Engineering and Machine Learning with MESA. Spica (α Virginis), a massive binary star system, offers insights into stellar evolution. Its orbital evolution, governed by the apsidal motion constant, reveals critical details about the stellar interior. However, calculating this constant using Modules for Experiments in Stellar Astrophysics (MESA) simulations is computationally demanding. To address this, we employed machine learning (ML) and deep learning (DL) methods to efficiently predict the apsidal constant. Random Forest and Recursive Neural Network emerged as the most effective ML and DL models, respectively, with luminosity, age, and temperature identified as key features. Our ensemble voting regressor, integrating ML and DL approaches, achieved superior accuracy. MESA models are consistent with recent constraints on Spica A's effective temperature, age, luminosity, and apsidal constant. This work promotes the potential of ML and DL in stellar research, advancing the understanding of the apsidal constant through stellar evolution.

Keywords: Stellar interiors, Apsidal motion, Binary stars, Neural networks, Stellar evolutionary models
Fundamental Parameters for a Sample of Field Blue Horizontal-branch Stars. With the aim of identifying hot field blue horizontal-branch (BHB) stars, spectroscopic observations of 21 candidates were carried out at the Observatoire du Mont-Mégantic. The fundamental parameters (effective temperature and surface gravity) of these targets were determined by fitting the observed Balmer line profiles with synthetic spectra computed with PHOENIX stellar atmosphere models at a metallicity of ‑1.5 dex solar. The radial velocity of each candidate was also measured. Our values of these three parameters are in agreement with those found in previous studies when available. Among the BHB stars studied here, only the star BD+07 5093 has an effective temperature close to the threshold of 11,500 K above which BHB stars are known to display a number of observational anomalies (such as photometric jumps and gaps, and abundance anomalies).

Keywords: Horizontal branch stars, Fundamental parameters of stars, Surface gravity, Stellar effective temperatures, Radial velocity, Stellar atmospheres
Dust and Coronal Lines in the Very Fast Nova V2361 Cygni. "Very fast" novae, with their high ejection velocities, smaller ejecta masses, high photospheric temperatures, and rapidly changing conditions are generally inhospitable to the formation and survival of dust. Here we present infrared spectra from multiple epochs of a rare exception, the nova V2361 Cygni. With its time to decline from peak visible brightness by two magnitudes (t2) of 6 days, V2361 Cygni is the third fastest nova known to have formed dust. At 23 days after peak brightness, its spectrum was dominated by emission from 1000 K dust with a luminosity of 1.6 × 104 L⊙. The dust persisted for an extended period and thermal emission was still prominent at 140 and 152 days post maximum. In another rarity, at those later two epochs V2361 Cygni exhibited coronal lines concurrent with its dust emission.

Keywords: Novae
Improved Formula for the Effect of Detector Deadtime on a Pulsar's Light Curve. M. Vivekanand derived an approximate formula for the distortion of the folded light curve of a pulsar caused by the detector deadtime τ. It contained a constant α that was ≈1 for small τ but had to be arbitrarily adjusted for larger τ. Here a better formula is derived that does not require α. Results are presented using this formula.

Keywords: X-ray stars
Non-detection of Low-frequency Radio Emission from MTP0015 and MTP044. The Irish LOFAR station was used to search for 110–190 MHz radio emission from two recently reported radio transients: MTP0015 and MTP0044. Periodic and single-pulse searches resulted in non-detections; here we report the derived limits.

Keywords: Radio astronomy, Radio pulsars, Pulsars
Will Nanodust Reappear in STEREO/WAVES Data?. Nanodust particles produced near the Sun by collisional breakup of larger grains are accelerated in the magnetised solar wind and reach high speeds outwards of 1 au. Vaporisation and ionization of fast dust grains impacting a spacecraft produce voltage pulses on wave instruments that enable them to act as dust detectors. Wave instruments on STEREO and on Cassini during its cruise phase detected a highly variable flux of fast nanodust. Both detections took place when the orientation of the solar magnetic dipole produced an interplanetary electric field that focused nanoparticles towards the heliospheric current sheet—a geometry that is recurring because of the periodicity of solar activity.

Keywords: Space vehicle instruments, Interplanetary dust, Solar wind, Heliosphere
Determination of the Abundance of Mercury from the Hg II Line at 5677.10 Å in Late B-type Stars. XIV. HD 172044. The weak line of Hg II located at 5677.10 Å is clearly detected in NARVAL I profiles of the HgMn star HD 172044. Spectrum synthesis shows that this line is properly reproduced by a mercury excess of about +5.95 dex, which also reproduces the profile of the commonly used Hg II line at 3983.93 Å. The synthesis of various spectral intervals also yields several new measurements of the abundances of carbon, nitrogen, oxygen, magnesium, aluminium, silicon, manganese, iron, and gallium. Most of these new measurements agree well with previous determinations.

Keywords: Mercury-manganese stars, Chemically peculiar stars
Supernova Code Comparison: FLASH and Athena. Galactic outflows play a crucial role in regulating the formation of stars in galaxies. For Milky-Way galaxies, supernovae power galactic outflows by depositing momentum into the interstellar medium. Numerical momentum deposition depends sensitively on the modeling of the Sedov–Taylor phase of supernova remnants. To determine the dependence of supernova remnant evolution on numerical methods employed, we performed three-dimensional hydrodynamic simulations of a Sedov-phase explosion in a homogeneous medium. We compare the evolution of the radius of the shock wave as simulated at uniform resolution, by two Eulerian grid codes (FLASH and Athena), varying the adiabatic index, ambient density, and numerical resolution. We find excellent agreement between the two codes and with the analytical solution, with relative errors &lt;5% in all cases investigated. We highlight the necessity for further study by employing other codes, ISM conditions, and physics modules within the simulation.

Keywords: Interstellar medium, Supernovae, Astronomical simulations
The Lines of the Noble Gases Kr II and Xe II Formed in the Atmosphere of HR 6000 (HD 144667). Lines of once-ionized krypton, an element rarely found in stellar spectra, are sought in high resolution Ultraviolet and Visible Echelle Spectrograph spectra of the sharp-lined star HR 6000. Among the five lines of Kr II probed, the line at 4355.48 Å is clearly present. As no quantitative measurement nor computation of the oscillator strength are available for this line, only a crude estimate of the abundance of krypton can be provided. Krypton is found to be overabundant with an excess of +2.70 dex respect to the solar abundance. Eight lines of Xe II are synthesized in order to derive the abundances of xenon in the atmosphere of HR 6000 using the current atomic data in the Atomic Spectra Database at National Institute of Standards and Technology. The mean excess in xenon is found to be +4.75 dex, with a large scatter, but in fair agreement with an earlier measurement.

Keywords: Mercury-manganese stars, Chemically peculiar stars
XRISM Observations of the Cooling Flow Cluster A2029 Support Heating by Mixing. I argue that the mixing-heating mechanism of the intracluster medium (ICM) is compatible with the new observations by the X-ray telescope XRISM that show the dispersion velocity in the cooling flow cluster of galaxies A2029 to be σv = 169 ± 10 km s‑1. Past jets from the central supermassive black hole induced turbulence; the velocity dispersion value indicates that the jets were powerful, as expected in the mixing-heating mechanism. Although the kinetic energy of the ICM turbulence that XRISM finds is short of heating the ICM and counter radiative cooling, the turbulence is fast enough to mix the hot shocked jets' material with the ICM on timescales shorter than the radiative cooling time. The support of the mixing-heating mechanism from determining the turbulent velocity I claim for A2029 is similar to the conclusion from the X-ray observations by the X-ray telescope Hitomi of the Perseus cluster.

Keywords: Galaxy clusters, Radio jets, Galactic and extragalactic astronomy, Abell clusters, Intracluster medium
The Lack of RR Lyrae Variable in the Ultrafaint Dwarf Galaxy Ursa Major III/UNIONS 1. Ursa Major III is the faintest known ultrafaint dwarf galaxy to date, and expected to lack of RR Lyrae due to its extreme faintness (MV = +2.2 mag). Using known all-sky RR Lyrae catalogs, I performed a dedicated search of RR Lyrae around Ursa Major III and found none. I concluded Ursa Major III indeed does not have any RR Lyrae.

Keywords: RR Lyrae variable stars, Compact dwarf galaxies
Identification of δ Scuti, γ Doradus Stars and Eclipsing Binaries with TESS. I analysed Transiting Exoplanet Survey Satellite (TESS) data of 62,912 stars for δ Scuti (DSCT) and γ Doradus (GDOR) stars within a selected temperature range of 6500–8100 K and a TESS magnitude range between 11 202 and 12 45. As a result, 15,542 new variables are discovered. Among these, I identified 5512 DSCT stars, 5655 GDOR stars (including 1426 hybrid δ Sct-γ Dor stars), 1710 eclipsing binary systems (415 with pulsating components).

Keywords: Eclipsing binary stars, Gamma Doradus variable stars, Delta Scuti variable stars, Pulsating variable stars
Apparent Diameters of F- to M-type Main-sequence Stars as Viewed from Habitable Zone Planets. We examine the apparent angular diameter of F2 to M5-type main-sequence stars as viewed from planets situated in their respective habitable zones. It is found that M-dwarfs appear largest, whereas F-type stars appear smallest, a result considered possibly counterintuitive. This outcome is unaffected by the adopted stellar models.

Keywords: Stellar types, Stellar astronomy, Habitable zone
Astronomical Seeing Prediction with Machine Learning. We investigate the use of supervised machine learning models to predict current atmospheric seeing at the Observatorio del Roque de Los Muchachos, La Palma. The prediction is made from current, local meteorological conditions as measured by an on-site weather station. The model was trained over a six-month period from 2024 February 8 to 2024 July 3. We found that a simple random forest method provides better prediction than an multilayer perceptron neural network. The most important predictor is the maximum wind speed over a one-minute interval (0.23), followed by air pressure (0.18), wind speed standard deviation (0.17), relative humidity (0.16), air temperature (0.13), wind direction (0.10) and average wind speed (0.06). All other features had importance &lt;0.05.

Keywords: Astronomical seeing