Sazuna/UAT_keywords huggingface dataset:
A Metallicity Catalog of Very Metal-poor Main-sequence Turn-off and Red Giant Stars from LAMOST DR10. We present a catalog of 8440 candidate very metal-poor (VMP; [Fe/H] ≤ ‑2.0) main-sequence turn-off (MSTO) and red giant stars in the Milky Way, identified from low-resolution spectra in LAMOST DR10. More than 7000 of these candidates are brighter than G ∼ 16, making them excellent targets for high-resolution spectroscopic follow-up with 4–10 m class telescopes. Unlike most previous studies, we employed an empirical calibration to estimate metallicities from the equivalent widths of the calcium triplet lines, taking advantage of the high signal-to-noise ratio in the red arm of LAMOST spectra. We further refined this calibration to improve its reliability for more distant stars. This method enables robust identification of VMP candidates with metallicities as low as [Fe/H] = ‑4.0 among both MSTO and red giant stars. Comparisons with metal-poor samples from other spectroscopic surveys and high-resolution follow-up observations confirm the accuracy of our estimates, showing a typical median offset of ∼0.1 dex and a standard deviation of ∼0.2 dex.

Keywords: Population II stars, Galaxy stellar content, Chemical abundances, Halo stars
The CatSouth Quasar Candidate Catalog for the Southern Sky and a Unified All-sky Catalog Based on Gaia DR3. The Gaia DR3 has provided a large sample of more than 6.6 million quasar candidates with high completeness but low purity. Previous work on the CatNorth quasar candidate catalog has shown that including external multiband data and applying machine learning methods can efficiently purify the original Gaia DR3 quasar candidate catalog and improve the redshift estimates. In this paper, we extend the Gaia DR3 quasar candidate selection to the Southern Hemisphere using data from SkyMapper, CatWISE, and Visible and Infrared Survey Telescope for Astronomy surveys. We train an XGBoost classifier on a unified set of high-confidence stars and spectroscopically confirmed quasars and galaxies. For sources with available Gaia BP/RP spectra, spectroscopic redshifts are derived using a pretrained convolutional neural network (RegNet). We also train an ensemble photometric redshift estimation model based on XGBoost, TabNet, and FT-Transformer, achieving a root mean square error of 0.2256 and a normalized median absolute deviation of 0.0187 on the validation set. By merging CatSouth with the previously published CatNorth catalog, we construct the unified all-sky CatGlobe catalog with nearly 1.9 million sources at G &lt; 21, providing a comprehensive and high-purity quasar candidate sample for future spectroscopic and cosmological investigations.

Keywords: Classification, Quasars, Astrostatistics techniques, Active galactic nuclei, Redshift surveys, Catalogs
MIRIS Paα Galactic Plane Survey. II. The Catalog of Paα Emission-line Sources. Using data from the MIRIS Paα Galactic Plane Survey (MIPAPS), we present a Paα 1.87 μm line image of the entire Galactic plane within the latitude range of −3° ≲ b ≲ +3°, revealing numerous Paα features. Based on the MIPAPS Paα image and the Wide-field Infrared Survey Explorer (WISE) H II region catalog, we compile a catalog of 1489 Paα emission-line sources in the Galactic plane within 90° ≤ ℓ ≤ 330°. By comparing our Paα images with Hα images constructed from the IPHAS and VPHAS+ survey data, we demonstrate the advantages of Paα line observations. We identify 902 Paα sources associated with H II regions, and newly confirm 619 H II region candidates as definitive H II regions through Paα or Hα detections. We also identify 261 extended and 326 pointlike Paα sources not included in the WISE catalog, most of which have Hα counterparts in the IPHAS or VPHAS+ images. A search of the SIMBAD database indicates that these sources originate from diverse object types. By measuring Paα and Hα fluxes, we estimate the E(B − V) color excesses derived from extended emissions for 138 Paα sources, showing good agreement with values obtained from spectrophotometry of ionizing stars in previous studies. Furthermore, we calculate total Lyman continuum luminosities for 42 Paα sources, providing constraints on the distances to H II regions and the spectral types of their ionizing stars. These results highlight the scientific potential of Paα line observations and the benefits of combining multiple hydrogen recombination lines in exploring ionized regions.

Keywords: Surveys, Galaxy structure, Interstellar dust extinction, H I line emission, Interstellar reddening, Interstellar objects, Interstellar medium, H II regions, Catalogs, Near infrared astronomy
A Search of Periodic Variable Stars in the LMC by JWST Photometry. Based on high-resolution near-infrared photometric data from the James Webb Space Telescope (JWST) targeting the Large Magellanic Cloud, this study attempts to evaluate the feasibility and sensitivity limits of variable star detection in crowded stellar fields. Through light-curve analysis, we identified a total of 304 periodic variable stars, including 71 EW-type eclipsing binaries, 7 EA-type eclipsing binaries, 177 rotational variables, 38 δ Scuti (DSCT) stars, and 12 RR Lyrae stars. Period–luminosity relations (PLRs) were derived for EW-type eclipsing binaries, DSCT stars, and RR Lyrae stars. The PLRs for EW-type and RR Lyrae stars are in good agreement with previous studies, while the PLR zero-point for DSCT stars appears systematically fainter by approximately 0.15–0.30 mag. Our PLRs exhibit low dispersion and are minimally affected by crowding. We analyzed the capability of JWST archival data to detect low-amplitude variables and found that only stars with amplitudes greater than approximately 0.05 mag can be reliably detected. Through simulations, we quantified how increasing the number of photometric epochs improves the detectability of low-amplitude, low signal-to-noise ratio variables. Despite current limitations in observational cadence, JWST demonstrates unique advantages in detecting short-period eclipsing binaries, rotational variables, and high-amplitude pulsators. Its exceptional spatial resolution enables high-precision PLR calibrations, offering new opportunities for future studies in variable star astrophysics and extragalactic distance measurements.

Keywords: Periodic variable stars, Delta Scuti variable stars, Large Magellanic Cloud, James Webb Space Telescope, RR Lyrae variable stars, Eclipsing binary stars
Catalog of Outbursts of Neutron Star Low-mass X-Ray Binaries. Many X-ray binaries (XRBs) are transiently accreting. Having statistics on their recurrence times is helpful to address questions related to binary evolution and populations, as well as the physics of binary systems. We compile a catalog of known outbursts of 87 transient neutron stars (identified through bursts or pulsations) and low-mass XRBs until mid-2025. Most outbursts are taken from the literature, but we also identify some outbursts from public X-ray monitoring lightcurves. We find 109 outbursts not previously identified in the literature; most are from the frequent transients GRS 1747-312 and the Rapid Burster MXB 1730-335, though we suspect that two outbursts from Liller 1 may be from another transient besides the Rapid Burster. We also find new outbursts for 10 other systems, and verify substantial quiescent intervals for XMM J174457-2850.3, XMMU J174716.1-281048, and AX J1754.2-2754. Outburst detection has been relatively efficient since 1996 for outbursts above FX (2–10 keV) = 3 × 10‑10 erg cm‑2 s‑1. While several systems have many known outbursts, 40 of the 87 systems we track have zero or one recorded outburst between 1996 and 2023. This suggests that many faint Galactic center XRBs may be neutron star XRBs, though we cannot completely rule out the proposition that most neutron star XRBs undergo frequent outbursts below all-sky monitor detection limits.

Keywords: Low-mass x-ray binary stars, Neutron stars, Accretion, Catalogs
PHANGS-HST Catalogs for ∼100,000 Star Clusters and Compact Associations in 38 Galaxies. II. Physical Properties from Decision-tree-based Spectral Energy Distribution Fitting of NUV-U-B-V-I Photometry with Categorical Priors Set by Hα Emission, Cluster Morphology, and Other Auxiliary Information. This paper is the second in a series presenting the catalogs and properties of the largest sample to date of ∼100,000 star clusters and compact associations, in 38 spiral galaxies observed by the PHANGS-HST Treasury survey. Here, we present spectral energy distribution (SED) fitting techniques used to compute the age, mass, and reddening for each object. Our decision-tree-based strategy incorporates categorical priors on model age, reddening, and metallicity determined from additional observed parameters: localized Hα emission, source morphology, and demographic-specific locations in the UBVI color–color diagram. This approach is implemented to mitigate model degeneracies, particularly between young dusty clusters and old clusters with minimal dust, which can have identical optical colors. Results based on Hα narrowband imaging from the ground and from Hubble Space Telescope are intercompared, and contrasted with previous SED-fitting efforts. The fraction of the population that is subject to such priors is ∼14%, and of this subset, ∼63% of old globular clusters (GCs) have ages that change by a factor of 10 or more relative to unconstrained fits with single metallicity (Z⊙) simple stellar population models. The demographics of the population are examined through age–mass and age–reddening diagrams (for individual galaxies as well as aggregated over the sample), and the GC mass function. We demonstrate relationships between cluster age–mass diagrams and properties of parent galaxies (galaxy morphology and location relative to the galaxy main sequence). We outline continuing efforts to improve the inference of physical properties, including the incorporation of JWST infrared photometry and updated synthesis models.

Keywords: Globular star clusters, Stellar associations, Spiral galaxies, Young massive clusters, Young star clusters, OB associations, Interstellar reddening, Galaxy evolution, Open star clusters, Barred spiral galaxies, Galaxies, Star clusters
Non-Parker Spiral Interplanetary Magnetic Field Configurations Observed in Near-Earth Space: Statistical Features of Their Occurrence and Solar Wind Conditions. In near-Earth space, the interplanetary magnetic field (IMF) is generally characterized by the Parker spiral configuration with a spiral angle of approximately 45° clockwise from the radial axis of the Sun. However, spacecraft observations reveal that IMF lines can exhibit non-Parker spiral configurations with either a nearly radial (outward–inward), tangential (westward–eastward), or normal (northward–southward) direction defined in radial–tangential–normal coordinates on even hourly timescales. Using the IMF and solar wind data measured by the Wind spacecraft for the period 1995–2023, we present distinctive features in the occurrence and various solar wind parameters between these non-Parker spiral IMF configuration types. Our study reveals that (1) the occurrence of non-Parker spiral IMF configuration types has the Hale cycle (∼22 yr magnetic dynamo cycle) variations with their own phases depending on the sign of the major IMF components, (2) the solar wind in the radial/tangential IMF structure is deflected eastward/westward, which corresponds to the direction opposite to/same as the rotation direction of the Sun on the plane perpendicular to the line of sight, and (3) these IMF configuration types can be characterized by magnetic field topology, which is open (for radial IMF and tangential IMF) or closed (for normal IMF). Our findings therefore provide insights into the formation mechanisms of these non-Parker spiral IMF configurations observed in near-Earth space. Moreover, our results suggest that spacecraft missions to various areas in interplanetary space are needed to better understand spatiotemporal evolutions of the solar-originated magnetic field structure in the heliosphere.

Keywords: Solar wind, Interplanetary magnetic fields
The Quasar-associated 2175 Å Dust Absorbers in the SDSS DR16 Quasar Catalog. We present, for the first time, a systematic study of quasar-associated 2175 Å dust absorbers using spectroscopic data from the Sloan Digital Sky Survey Data Release 16 (DR16). By analyzing the optical spectra and multiband magnitudes of 557,674 quasars in the redshift range of 0.7 ≤ z ≤ 2.4, we identify 843 absorbers that share the same redshifts as quasars and are believed to originate from dust in the quasar nuclei, the host galaxies, or their surrounding environments. These absorbers exhibit weak bump strengths (Abump = 0.49 ± 0.15 μm‑1) and narrow widths (γ = 0.81 ± 0.14 μm‑1), while their peak positions span a broad range from x0 = 4.2 to 4.84 μm‑1. Their average extinction curves resemble those of the Large Magellanic Cloud but exhibit a shallower slope. In broad-absorption-line quasars, the absorption bumps show systematic shifts in peak positions. Although further confirmation is needed, this may suggest environmental differences in dust grain properties. We find a statistically significant negative correlation between the bump strength and redshift, suggesting possible evolution in dust properties. These findings highlight the changing composition and physical conditions of dust in quasar environments, likely influenced by factors such as metallicity, radiation fields, and dust-processing mechanisms. Future studies incorporating ultraviolet and infrared data will be essential for refining the dust evolution models. Machine learning techniques and high-resolution spectroscopic follow-ups could enhance the sample completeness and provide deeper insights into the chemical properties of the dust absorbers.

Keywords: Interstellar extinction, Galaxy evolution, Interstellar medium, Quasars
A JWST Study of Polycyclic Aromatic Hydrocarbon Emission in a Region of 30 Doradus. Polycyclic aromatic hydrocarbons (PAHs) are responsible for strong mid-IR emission features near star-forming regions. It is well known that low-metallicity environments exhibit weaker PAH emission, but it is not clear how metallicity affects the properties of the emitting PAH population. We present a detailed study of the PAH emission in a region of 30 Doradus (30 Dor), a well-known low-metallicity star-forming environment in the Large Magellanic Cloud and we compare it to PAH emission in the Orion Bar to investigate the characteristics of the PAH population and how the environments affect the resulting IR emission. We analyze JWST observations of 30 Dor that include imaging (NIRCam and MIRI) and spectroscopy (NIRSpec integral-field unit (IFU) and MIRI Medium Resolution Spectroscopy (MRS)). We extracted NIRSpec/IFU and MIRI/MRS spectra from 18 apertures that cover the morphological structures present within the observed region of 30 Dor. We characterize the profiles and relative intensities of PAH emission in these apertures. The detailed profiles of the PAH emission bands in 30 Dor are all similar and match with one of the dissociation fronts (DF2) in the Orion Bar, but their relative band ratios show a much larger range than in the Orion Bar. The PAH emission in 30 Dor originates from a population with a lower or similar ionization fraction than in the Orion Bar, and a size distribution that has more small-sized PAHs. Since smaller PAHs typically photofragment before larger PAHs, our findings support the hypothesis that the lower PAH emission due to lower metallicities is the result of the inhibition of growth toward larger PAHs rather than photofragmentation.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Infrared spectroscopy, Large Magellanic Cloud, Astrochemistry, Interstellar medium
pySTARBURST99: The Next Generation of STARBURST99. STARBURST99 is a population synthesis code tailored to predict the integrated properties or observational characteristics of star-forming galaxies. Here, we present an update to STARBURST99 where we port the code to Python and include new evolutionary tracks, both rotating and nonrotating, at a range of low-metallicity environments. We complement these tracks with a corresponding grid of new synthetic spectral energy distributions (SEDs). Additionally, we include both evolutionary and spectral models of stars up to 300–500 M⊙. Synthesis models made with the Python version of the code and new input stellar models are labeled pySTARBURST99. We make new predictions for many properties, such as ionizing flux, SED, bolometric luminosity, wind power, hydrogen line equivalent widths (EWs), and the UV β-slope. These properties are all assessed over wider coverage in metallicity, mass, and resolution than in previous versions of STARBURST99. A notable finding from these updates is an increase in H I ionizing flux of 0.3 dex in the first 2 Myr when increasing the upper mass limit from 120 to 300 M⊙. Changing metallicity has little impact on H I in the first 2 Myr (range of 0.015 dex from Z = 0.02 to 0.0), but lower metallicities have higher H I by 1 dex (compared to Z = 0.02–0.0004) at later times, with Z = 0.0 having even higher H I at later times. Rotating models have significantly higher H I than their equivalent nonrotating models at any time after 2 Myr. Similar trends are found for He I and He II, bolometric luminosity and wind momentum, with more complex relations found for hydrogen line EWs and UV β-slopes.

Keywords: Starburst galaxies, Massive stars
A Catalog of Local Universe Fast Radio Bursts from CHIME/FRB and the KKO. We present the first catalog of fast radio burst (FRB) host galaxies from CHIME/FRB Outriggers, selected uniformly in the radio and the optical by localizing 81 new bursts to 2″ × ∼ 60″ accuracy using CHIME and the k'niʔatn k'l ⌣ stk'masqt Outrigger station, located 66 km from CHIME. Of the 81 localized bursts, we use the probabilistic association of transients to their hosts algorithm to securely identify 21 new FRB host galaxies, and compile spectroscopic redshifts for 19 systems, 15 of which are newly obtained via spectroscopic observations. The most nearby source is FRB 20231229A, at a distance of 90 Mpc. One burst in our sample is from a previously reported repeating source in a galaxy merger (FRB 20190303A). Three new FRB host galaxies (FRBs 20230203A, 20230703A, and 20231206A) are found toward X-ray and optically selected galaxy clusters, potentially doubling the sample of known galaxy cluster FRBs. A search for radio counterparts reveals that FRB 20231128A is associated with a luminous persistent radio source (PRS) candidate with high significance (Pcc ∼ 10−2). If its compactness is confirmed, it would be the nearest known compact PRS at z = 0.1079. Our catalog significantly increases the statistics of the Macquart relation at low redshifts (z &lt; 0.2). In the near future, the completed CHIME/FRB Outriggers array will produce hundreds of FRBs localized with very long baseline interferometry (VLBI). This will significantly expand the known sample and pave the way for future telescopes relying on VLBI for FRB localization.

Keywords: Radio transient sources
Efficient Searches for Small Signals across Two-channel Noisy Data: A Challenge in Big-data Observations. Searching for novel small signals in noisy data is preferably pursued by correlation in two or more independently operating channels. Signals of potential interest exist in tails beyond κσ, where κ denotes a multiple of the standard deviation σ of the data. Since moving data is a major cost factor in big-data analysis and heterogeneous computing more generally, efficiency may be optimized by restricting the computation of correlations to the tails of two-channel data exceeding κσ. Already, a moderate value κ ≳ 2 realizes a data reduction by at least an order of magnitude. Here, we study this approach using a novel excess probability ratio (EPR), correlating Boolean data resulting from tails beyond a cutoff κσ. We compare and rank EPR performance against conventional direct cross correlation and the Pearson coefficient (PC), applicable to the original data with no cutoff. This benchmark is performed over different combinations of background noise (Gaussian, Poisson and uniform) and signals (Gaussian, Poisson, uniform, chirps and sine waves). Results show the performance of EPR to be comparable to that of the PC, providing a new approach for significant improvements in efficiency with essentially no loss of sensitivity, relevant to the present era of big-data observatories.

Keywords: Astronomy data analysis
An Extremely Deep Rubin Survey to Explore the Extended Kuiper Belt and Identify Objects Observable by New Horizons. A proposed Vera C. Rubin Observatory deep-drilling microsurvey of the Kuiper Belt will investigate key properties of the distant solar system. Utilizing 30 hr of Rubin time across six 5 hr visits over 1 yr starting in summer 2026, the survey aims to discover and determine orbits for up to 730 Kuiper Belt objects (KBOs) to an r-magnitude of 27.5. These discoveries will enable precise characterization of the KBO size distribution, critical for understanding planetesimal formation. By aligning the survey field with NASA's New Horizons spacecraft trajectory, the microsurvey will facilitate discoveries for the mission operating in the Kuiper Belt. Modeling based on the Outer Solar System Origin Survey predicts at least 12 distant KBOs observable with the New Horizons LOng Range Reconnaissance Imager (LORRI) and approximately three objects within 1 au of the spacecraft, allowing higher-resolution observations than Earth-based facilities. LORRI's high-solar-phase-angle monitoring will reveal these objects' surface properties and shapes, potentially identifying contact binaries and orbit-class surface correlations. The survey could identify a KBO suitable for a future spacecraft flyby. The survey's size, depth, and cadence design will deliver transformative measurements of the Kuiper Belt's size distribution and rotational properties across distance, size, and orbital class. The high stellar density in the survey field also offers synergies with transiting exoplanet studies.

Keywords: Sky surveys, Kuiper belt
Advancing Cosmological Parameter Estimation and Hubble Parameter Reconstruction with Long Short-term Memory and Efficient Kolmogorov–Arnold Networks. In this work, we propose a novel approach for cosmological parameter estimation and Hubble parameter reconstruction using long short-term memory (LSTM) networks and efficient Kolmogorov–Arnold networks (Ef-KAN). LSTM networks are employed to extract features from observational data, enabling accurate parameter inference and posterior distribution estimation without relying on solvable likelihood functions. This method achieves performance comparable to traditional Markov Chain Monte Carlo techniques, offering a computationally efficient alternative for high-dimensional parameter spaces. By sampling from the reconstructed data and comparing it with mock data, our designed LSTM constraint procedure demonstrates the superior performance of this method in terms of constraint accuracy, and effectively captures the degeneracies and correlations between the cosmological parameters. Additionally, the Ef-KAN model is introduced to reconstruct the Hubble parameter H(z) from both observational and mock data. Ef-KAN is an entirely data-driven approach, free from prior assumptions, and demonstrates superior capability in modeling complex, nonlinear data distributions. We validate the Ef-KAN method by reconstructing the Hubble parameter, demonstrating that H(z) can be reconstructed with high accuracy. By combining LSTM and Ef-KAN, we provide a robust framework for cosmological parameter inference and Hubble parameter reconstruction, paving the way for future research in cosmology, especially when dealing with complex data sets and high-dimensional parameter spaces.

Keywords: Maximum likelihood estimation, Bayesian statistics, Astrostatistics, Cosmological parameters from large-scale structure