Sazuna/UAT_keywords huggingface dataset:
Planetary Habitability Under the Light of a Rapidly Changing Star. Planetary atmospheric energy budgets primarily depend on stellar incident flux. However, stellar variability can have major consequences for the evolution of planetary climates. In this work, we evaluate how stellar variability influences the equilibrium temperature and water retention of planets within the habitable zone (HZ). We present a sample of nine stars that are known to host at least one planet within the HZ and that were identified to have a variability amplitude exceeding 100 ppm based on photometry from the Transiting Exoplanet Survey Satellite. We investigate the effect that the variability of these stars has on the insolation flux of their HZ planets and the resulting changes in the induced planetary equilibrium temperature. Our results show that for the stars in our sample, the stellar variability has an insignificant effect on the equilibrium temperature of HZ planets. However, we also emphasize that these stars are not representative of more extreme variable stars, since exoplanets are more difficult to detect and characterize in the presence of extreme variability. We also investigate the equilibrium temperature and long-term evolution of a hypothetical Earth-like planet placed at the inner edge of the HZ around a highly variable star. We found that the water loss rates are comparable between both variable and quiet host stars for Earth-like planets in the inner HZ. Overall, these results broaden our knowledge of the impact of stellar variability on planetary habitability.

Keywords: Exoplanets, Habitable zone, Habitable planets, Variable stars
Is Crater II Disrupting?. Crater II (CraII) is a very intriguing low surface brightness and extended galaxy in the vicinity of our Galaxy. Motivated by its huge area and the number of RR Lyrae stars (RRLSs) detected near to its core, we performed a follow-up campaign to get deep multiband (g, i) and multiepoch DECam observations in the outskirts of CraII, covering up to 8rh in the northeast direction and up to 13rh in the southwest direction (spanning almost 10° in the sky across the galaxy). We confirm the existence of tails coming out from CraII. In our survey, we detected a total of 97 periodic variable stars, of which 44 are CraII members (37 RRLSs and 7 anomalous Cepheids). The RRLSs show a strong gradient in distance of 3.7 kpc deg−1, which follows the relation  d(kpc)=(−3.70±0.21)ξ'+(116.2±0.32)  (where  ξ'  is the planar coordinate rotated to fit the CraII tails). We also found an indication that the gradient in distance in the distant part of the near-side tail (northeast) may be less steep than it is in the inner 5°. The leading tail also displays a significant overdensity of RRLSs located ∼3 .° 25 from the center of CraII. Despite covering a smaller area than previous works, our deeper photometry has allowed us to unveil more variable stars in the region and better define the tidal tails of CraII.

Keywords: Local Group, Stellar streams, Anomalous Cepheid variable stars, Tidal disruption, Galaxy structure, Dwarf galaxies, RR Lyrae variable stars
AstroQ: Automated Scheduling of Cadenced Astronomical Observations. Astronomy relies heavily on time-domain observations. To maximize the scientific yield of such observations, astronomers must carefully match the observational cadence to the phenomena of interest. This presents significant scheduling challenges for observatories with multiple large programs, each with different cadence needs. To address this challenge, we developed AstroQ, an automated framework for scheduling cadenced observations. We tested this on a suite of Doppler exoplanet programs at Keck Observatory, where the algorithm powers the KPF Community Cadence project. As a point of reference, AstroQ can determine the provably optimal ordering of 3680 observations of 200 targets—each with its own cadence needs and accessibility constraints—over a 6 month period to 5 minute time resolution. Schedules of this size may be constructed in ∼120 s on a modern workstation, enabling dynamic rescheduling due to weather changes, target-of-opportunity interrupts, and other needs. A key advantage of AstroQ over manual scheduling is realistic projections of program completion, savings in human effort, and elimination of human bias in balancing many programs. AstroQ is open source and may be applied to other scheduling needs, both in astronomy and beyond.

Keywords: Automated telescopes, Radial velocity
An Improved Machine Learning Approach for Radio Frequency Interference Mitigation in FAST─SETI Survey Archival Data. The search for extraterrestrial intelligence (SETI) commensal surveys aim to scan the sky to detect technosignatures from extraterrestrial life. A major challenge in SETI is the effective mitigation of radio frequency interference (RFI), a critical step that is particularly vital for the highly sensitive Five-hundred-meter Aperture Spherical radio Telescope (FAST). While initial RFI mitigation (e.g., removal of persistent and drifting narrowband RFI) are essential, residual RFI often persists, posing significant challenges due to its complex and various nature. In this paper, we propose and apply an improved machine learning approach, the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm, to identify and mitigate residual RFI in FAST─SETI commensal survey archival data from 2019 July. After initial RFI mitigation, we successfully identify and remove 36,977 residual RFIs (accounting for ∼77.87%) within approximately 1.678 s using the DBSCAN algorithm. This result shows that we have achieved a 7.44% higher removal rate than previous machine learning methods, along with a 24.85% reduction in execution time. We finally find interesting candidate signals consistent with previous studies, and retain one candidate signal following further analysis. Therefore, DBSCAN algorithm can mitigate more residual RFI with higher computational efficiency while preserving the candidate signals that we are interested in.

Keywords: Search for extraterrestrial intelligence, Radio astronomy, Astronomy data analysis
Benchmarking Dimensionality Reduction Methods for High-dimensional ALMA Image Cubes. High-dimensional astronomical data cubes provide a wealth of spectral and structural information that can be used to study astrophysical and chemical processes. The complexity and sheer size of these datasets pose significant challenges in their efficient analysis, visualization, and interpretation. In specific astronomical use cases, a number of dimensionality reduction techniques, including traditional linear (e.g., principal component analysis) and modern nonlinear methods (e.g., convolutional autoencoders) have been used to tackle this high-dimensional problem. In this study, we assess the strengths, weaknesses, and nuances of various methods in their ability to capture and preserve astronomically relevant features at lower dimensions. We provide recommendations to guide users in identifying and incorporating these treatments to their data, and provide insights into the computational scalability of these methods for observatory-level data processing. This benchmark study uses publicly available archival Atacama Large Millimeter/submillimeter Array (ALMA) data from a diverse sampling of source morphologies and observing setups to assess the performance and trade-offs between computational cost, image reconstruction accuracy, and scalability. Finally, we discuss the generalizability of these techniques in regard to data segmentation and labeling algorithms, and how they can be exploited for advanced data product generation and streamlined archival analysis as we prepare to enter the era of the ALMA Wideband Sensitivity Upgrade.

Keywords: Radio astronomy, Astronomy data analysis, Astronomy image processing
The Pleiades Binary Fraction Revisited. One of the nearest and best-studied open clusters, the Pleiades is an important cornerstone of stellar astrophysics. Despite its role as a reference coeval stellar population, its multiplicity properties are still not well characterized. The combined use of Gaia Data Release 3 multiband photometry, the renormalized unit weight error (RUWE) astrometric parameter, and non-single-star solutions, along with available ground-based spectroscopic, high-angular-resolution, and polarimetric observations, enable more robust constraints on the binary-star population in the cluster. Several conclusions may have broader implications for other stellar populations. Twin binaries, with mass ratios close to q ∼ 1, tend to have lower RUWE values, increasing their membership selection probability relative to q ∼ 0.5 systems that are disfavored. The frequently observed peak in mass ratio distribution for q ∼ 1 binaries may be partially attributed to this bias. Photometrically fitted mass ratios are underestimated for double-lined spectroscopic binaries, in agreement with other authors. Differential extinction photometrically mimics stellar binarity. An area of enlarged absorption is traced by increased polarization south of the Merope star and excluded from the analysis to avoid this bias. The fraction of systems with q &gt; 0.6 companions is measured to be  f=16.4%−0.6+2.6  for m &gt; 0.5 M⊙ stars, which is larger than recent Gaia-based estimates, but compatible with the pre-Gaia values for Pleiades and the field population. The binary fraction shows no steady increase with stellar mass in the 0.5─1.2 M⊙ range, while the mass ratio has a bimodal distribution with a minimum near q ∼ 0.7.

Keywords: Multiple stars, Binary stars, Multi-color photometry, Spectroscopic binary stars, Mass ratio, Astrometric binary stars, Wide binary stars, Open star clusters, Gaia
Revisiting the Atmosphere of HAT-P-70b with CARMENES High-resolution Transmission Spectroscopy. Owing to hot and inflated envelopes that facilitate atmospheric studies, ultrahot Jupiters (UHJs) have attracted much attention. Significant progress has been achieved, from enlarging the sample size to broadening the studies to encompass diverse stellar types and ages. Here, we present a transmission spectroscopy study of HAT-P-70b, a UHJ orbiting a young A-type star, through high-resolution observations with CARMENES at the 3.5 m Calar Alto telescope. By using the line-by-line technique, we confirm the previous detections of Hα, Na I, and Ca II, report a new tentative detection of K I, and impose an upper limit on the He triplet absorption. Through cross-correlation analysis, we identify the Ca II and Fe I absorptions, both blueshifted by approximately 5 km s−1, indicating a day-to-night side atmospheric wind. Additionally, we find a new tentative detection of K I. We do not see any significant atmospheric molecular signal in the near-infrared data. Putting HAT-P-70b in the context of UHJs from the literature, it turns out that (1) Hα absorption is more common on gas giants orbiting stars younger than 1 Gyr, with a relative detection probability of PAge&lt;1 Gyr(Hα)/PAge≥1 Gyr(Hα) ∼ 3; (2) any UHJ is likely to exhibit Fe I absorption if it has Ca II.

Keywords: High resolution spectroscopy, Exoplanet atmospheric composition , Hot Jupiters, Transmission spectroscopy, Exoplanet atmospheres
Predictions of the LSST Solar System Yield: Neptune Trojans. The NSF-DOE Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), beginning full operations in late 2025, will dramatically transform solar system science by vastly expanding discoveries and providing detailed characterization opportunities across all small-body populations. This includes the co-orbiting 1:1 resonant Neptune Trojans (NTs), which are thought to be dynamically hot captures from the protoplanetary disk. Using the survey simulator Sorcha, combined with the latest LSST cadence simulations, we present the very first predictions for the NT yield within the LSST. We forecast a model-dependent median number of ∼130─300 discovered NTs, and infer a notable 2:1 detection bias toward the recently emerged L5 cloud near the Galactic plane versus the L4 cloud, reflecting the lower-cadence coverage in the Northern Ecliptic Spur region that suppresses L4 detections. The additionally simulated Science Validation survey will offer the very first early insights into this understudied cloud. Around 60% of detected main survey NTs will meet stringent color light-curve quality criteria, increasing the sample size more than fourfold compared to existing datasets. This enhanced sample will enable robust statistical analyses of NT color and size distributions, crucial for understanding their origins and relationship to the broader trans-Neptunian population. These comprehensive color measurements represent a major step forward in characterizing the NT population and will facilitate future targeted spectroscopic observations.

Keywords: Sky surveys, Small Solar System bodies, Neptunian satellites, Trojan asteroids, Neptune trojans
The Open Cluster Chemical Abundances and Mapping Survey. VIII. Galactic Chemical Gradient and Azimuthal Analysis from SDSS/MWM DR19. The Open Cluster Chemical Abundances and Mapping (OCCAM) survey seeks to curate a large, comprehensive, uniform dataset of open clusters and member stars to constrain key Galactic parameters. This eighth entry from the OCCAM survey, based on the newly released Sloan Digital Sky Survey V/Milky Way Mapper Data Release 19 (DR19), has established a sample of 158 quality open clusters that are used to constrain the radial and azimuthal gradients of the Milky Way. The DR19 cluster sample [Fe/H] abundances are largely consistent with measurements from other large-scale spectroscopic surveys. However, the gradients we calculate deviate considerably for some elements. We find an overall linear Galactic radial [Fe/H] gradient of −0.079 ± 0.006 dex kpc−1 using the cluster's current Galactocentric radius and a gradient of −0.071 ± 0.005 dex kpc−1 with respect to the cluster's guiding center radius. We do not find strong evidence for significant evolution of the differential element gradients ([X/Fe]) investigated here (O, Mg, Si, S, Ca, Ti, Cr, Mn, Co, Ni, Na, Al, K, Ce, Nd), and instead show indications that the radial [Fe/H] gradient does not change significantly with stellar population age. For the first time, using the OCCAM sample, we have sufficient numbers of clusters to investigate Galactic azimuthal variations. In this work, we find evidence of azimuthal variations in the measured radial abundance gradient in the Galactic disk using our open cluster sample.

Keywords: Open star clusters, Galactic abundances, Chemical abundances, Milky Way evolution
Hipparcos, Gaia, and Radial Velocities Reveal that the Radio-emitting F Star HD 220242 Has an M Dwarf Companion, a Likely Source of the Radio Emission. The detection of circularly polarized, low-frequency radio emission offers the tantalizing possibility of observing interactions between stars and their possible substellar companions, as well as direct emission from exoplanets. Additional follow-up of systems with radio emission is key to understanding the true origin of the emission, since multiple astrophysical mechanisms can plausibly lead to such signals. While 19 M dwarfs were detected by the LOw-Frequency ARray in circular polarization as part of the V-LoTSS survey, HD 220242 is the only F star to have a circularly polarized, low-frequency radio detection in the same survey. We conducted radial velocity (RV) follow-up with the Habitable-zone Planet Finder and combined these observations with additional archival RVs and Hipparcos-Gaia proper motion accelerations to determine that HD 220242 has a stellar companion with P = 16.79 ± 0.04 yr and a mass of 0.619 ± 0.014 M⊙. We use spectral energy distribution fitting and lack of any UV excess to rule out a coevolved white dwarf companion, and confirm that the companion is an M dwarf star. Given that F stars lack the coronal properties to produce such coherent emission, and the companion mass and lack of UV excess are consistent with an M dwarf, the radio emission is most plausibly associated with the companion. *Based on observations obtained with the Hobby─Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians-Universität München, and Georg-August Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Radial velocity, Binary stars
The Identification of New Herbig Ae/Be Stars from LAMOST DR7. Herbig Ae/Be stars (HAeBes) are critical tracers of intermediate- and high-mass star formation, yet their census remains incomplete compared to low-mass young stellar objects like T-Tauri stars. To expand the known population, we systematically searched for HAeBes in LAMOST DR7 low-resolution spectra. Following Sun et al., we applied Uniform Manifold Approximation and Projection for dimensionality reduction and Support Vector Machine classification, identifying ∼240,000 spectra with potential Hα emission. After removing contaminants (nonstellar objects, extragalactic sources, cataclysmic variables, and Algol systems) and restricting to B/A-type stars, we obtained 1835 candidates through 2MASS/WISE visual inspection. Spectral energy distribution analysis confirmed 143 sources with infrared excess (J band or longer wavelengths), including 92 known HAeBes. From the remaining 51 candidates, we classified 26 with strong infrared excess as new HAeBes. Color-index analysis of confirmed HAeBes and classical Ae/Be stars (CAeBes) revealed that the (K − W1)0 versus (W2 − W3)0 diagram effectively separates these populations: CAeBes predominantly occupy (K − W1)0 ≤ 0.5 and (W2 − W3)0 ≤ 1.1, while other regions trace transition disks ((K − W1)0 &lt; 0.5 and (W2 − W3)0 &gt; 1.1), globally depleted disks ((K − W1)0 &gt; 0.5 and (W2 − W3)0 &lt; 1.1), and Class I/Flat/II HAeBes ((K − W1)0 &gt; 0.5 and (W2 − W3)0 &gt; 1.1). More importantly, the HAeBes exhibit a clear evolutionary gradient on this diagram, with those in the Class III, Class II, Flat-SED, and Class I evolutionary stages being effectively distinguished by concentric ellipses that are roughly centered at (0, 0) with semimajor axes of a = 1.5, a = 3.0, and a = 4.0, and a semimajor to semiminor axis ratio of 1.6:1.

Keywords: Herbig Ae/Be stars, Young stellar objects, Spectral energy distribution
Research on Multiclassification Algorithm of Ultrawideband Pulsar RFI Based on MobileNetV2. Radio telescopes are susceptible to radio frequency interference (RFI) during observations, which introduces noise and artificial signals into astronomical data. Failure to properly process RFI-contaminated data can severely compromise data reliability and even lead to erroneous scientific conclusions. Consequently, RFI identification and mitigation have become critical scientific challenges in radio astronomy. This study proposes an RFI recognition and data cleaning method based on a deep learning image classification algorithm (RFI-MobileNetV2, RFI-MN). By performing feature extraction and preliminary classification on visual astronomical data, the method aims to effectively mitigate RFI, improve the data signal-to-noise ratio, and provide more reliable data support for astronomical research. Using the lightweight convolutional neural network MobileNetV2 as the core architecture, the model achieves efficient extraction and classification of diverse RFI features, thereby providing an effective solution for subsequent RFI suppression tasks. For the experiments, a dataset containing multiple RFI types was constructed as a training sample. During model optimization, performance was significantly enhanced through the integration of an attention mechanism, modification of the activation function in inverted residuals, and multiscale feature fusion. Evaluation metrics including precision, recall, and F1 score were employed to verify the scheme's effectiveness through baseline training, inference, multimodel comparison, and ablation experiments. The results demonstrate that the optimized RFI-MN achieves performance exceeding 94%, substantially outperforming other comparative models and providing an effective solution for RFI-affected astronomical data preprocessing.

Keywords: Astronomy image processing, Astronomy data analysis, Astronomy data acquisition
ASASSN-24fw: Candidate Gas-rich Circumsecondary Disk Occultation of a Main-sequence Star. Dusty disks around planetary and substellar companions in outer reaches of exoplanetary systems can be detected as long-lasting occultations, provided the observer is close to the secondary's orbital plane. Here we report optical spectroscopy with KOSMOS (Apache Point Observatory), MagE (Magellan), and GHOST (Gemini-S) of ASASSN-24fw (Gaia 07:05:18.97+06:12:19.4), a 4 mag dimming event of a main-sequence star which lasted 8.5 months. We discover multiple low-ionization metal emission lines with velocity dispersion ≲ 10 km s−1 blueshifted by 27 km s−1 with respect to the star, as well as kinematically complex Na D absorption. If associated with the occulter, these detections suggest that the occulter is gas rich. Further, we detect a blueshifted and broad (∼200 km s−1) Hα line, which likely originates in the inner circumstellar disk. We confirm the previously reported occultations in 1981 and 1937 seen in historic data, yielding a semimajor axis of the occulter's orbital motion around the star of 14 au. If the occulter is a circumsecondary disk filling 30%─100% of the Hill radius, we estimate the minimum mass of the secondary to be a few Jupiter masses and a disk mass of 1% of the mass of the Moon. Given the age of the star (&gt;2 Gyr), the disk is unlikely to be a survivor of the planet formation stage and may be the result of a planetary collision. If the Na D absorption and/or metal emission lines originate in the disk, the observations presented here are the first discovery of a circumsecondary disk wind or rotation.

Keywords: Circumstellar disks, Exoplanet structure, Exoplanet formation, Debris disks, Occulting disks
The Trajectory of 3I/ATLAS Through the Inner Solar System: Close Encounters and Possible Collisions. 3I/ATLAS is the third interstellar object (ISO) identified to date. Unlike other known ISOs, 3I/ATLAS travels on a nearly ecliptic, retrograde orbit (i ≍ 175°). This trajectory, combined with a small perihelion distance (q ≍ 1.36 au), directs it through the relatively dense populated regions of the main-belt asteroids (MBAs) and near-Earth asteroids (NEAs), moving counter to their general prograde motion. This work focused on an investigation of close encounters and assessment of collision probabilities between 3I/ATLAS and the populations of MBAs/NEAs. The N-body numerical integration was performed to identify close approaches within distance ≤0.03 au on the time range from 2025 August 1 till 2026 April 1 (3I/ATLAS's heliocentric distance exceeded the Jupiter's orbit). The Monte Carlo (MC) simulations were used to estimate collision probabilities, accounting to the orbital uncertainties of asteroids which have the smallest approach distances. Performed search identified 736 MBAs and 31 NEAs that will have a close approach with 3I/ATLAS at a physical distance of ≤0.03 au. While no direct collisions are predicted based on nominal orbits, our analysis highlights the case of MBA 2020 BG107. Due to its high orbital uncertainty, its 3σ positional ellipsoid at the time of the encounter is larger than the nominal approach distance to 3I. The collision probability is estimated at 0.025% within our MC simulations. The results could be extrapolated in regard to the solar system comets from Oort cloud on parabolic or hyperbolic orbits, as dynamically (except the velocity) they are similar to the interstellar objects.

Keywords: Orbital motion, Close encounters, Small Solar System bodies, Interstellar objects