Sazuna/UAT_keywords huggingface dataset:
Observations with the Southern Connecticut Stellar Interferometer. II. First Three-telescope Observations and a New Diameter Measurement of Arcturus. We discuss the most recent observations made with the Southern Connecticut Stellar Interferometer, which is a three-station stellar intensity interferometer located on the campus of Southern Connecticut State University, in New Haven, Connecticut. Two different kinds of observations are presented. We first analyze observations of Vega taken in a three-telescope mode. (Previously, the instrument had only two operational stations.) We show that, while the efficiency remains nearly identical to that reported in our last paper, the addition of the third station allows more photon data to be recorded simultaneously, and therefore we can build up the photon-bunching peak in the data stream in fewer hours on sky for an unresolved source. In the second part of the paper, we report our observations to date of the nearby red giant star Arcturus, most of which occurred in the first half of 2025. These show that, as a partially resolved source at the baselines we used, we detect fewer correlations in the photon-bunching peak than for an unresolved source of comparable brightness. Combining the data with speckle imaging observations taken at Apache Point Observatory, we derive a new measurement of Arcturus' diameter that extends the temporal baseline of interferometric observations of the star and is consistent with previous analyses made by other investigators.

Keywords: Stellar radii, Astronomical instrumentation, Field stars, Interferometers
A Not-so-compact Companion: Massive, Oversized White Dwarf in a Post-common-envelope Eclipsing Binary. We provide a detailed characterization of 2M07515777+1807352, a post-common-envelope eclipsing binary system with a 10.3-day, nearly (but not quite) circular orbit (e = 0.02). This system consists of a massive white dwarf (WD; 1.08 M⊙) and a 4400 K main-sequence companion (0.66 M⊙). This WD is among the most massive known within post-common-envelope binary systems. We also find, through both spectral energy distribution and TESS light-curve analyses, that the WD has a radius of 1.54 ± 0.07 R⊕, roughly 12σ larger than the expected value from WD mass─radius relationships. Both the Lomb─Scargle analysis and the  vsini  of the system indicate that the main-sequence companion is supersynchronously rotating at a period of ∼6 days, which may suggest that accretion occurred during the evolution of the system. This binary also shares similar physical characteristics with six other post-common-envelope systems hosting massive WDs, which may point to a shared formation pathway. We model the history of this system with COSMIC and find that it likely formed through an episode of common-envelope evolution following the onset of mass transfer when the progenitor primary was on either the early or thermally pulsing stages of the asymptotic giant branch. As a result of its properties, the study of 2M07515777+1807352 can provide new insights regarding many key outstanding questions in our understanding of common-envelope evolution.

Keywords: Binary stars, Multiple star evolution, Close binary stars, White dwarf stars, Stellar evolution, Stellar physics, Eclipsing binary stars, Common envelope evolution, Common envelope binary stars
Estimating Accretion Times of Halo Substructures in the Milky Way. To unravel the formation history of the Milky Way, we estimate the accretion times of six phase-space substructures in the stellar halo, using the orbital frequencies toward two spatial directions (r, ϕ) in spherical coordinates. These substructures, identified in our previous studies, are located in the solar neighbourhood and therefore have high-precision astrometry from Gaia. The uncertainties of the results are determined using the Monte Carlo method, and the significance is established through comparison with random halo samples. The results for the substructure GL-1 in both directions show good consistency and high significance (4.3σ and 3.9σ), yielding a combined accretion time of 5.6 ± 0.1 Gyr ago, where the uncertainties quoted are statistical only. The substructures GL-4 and GR-1, with smaller pericenters, exhibit higher significance in the less massive potential of the Milky Way, implying that the more massive potential may overestimate the central mass, especially the bulge. The accretion times of GL-4 and GR-1 are 6.9 ± 0.3 Gyr with a confidence of 3.7σ, and 2.0 ± 0.1 Gyr with a confidence of 4.4σ, respectively. Further constraints on the accretion times of phase-space substructures require more precise astrometric data, e.g., by Gaia DR4, China Space Station Survey Telescope and Roman space telescope.

Keywords: Stellar streams, Galactic archaeology, Milky Way dynamics, Solar neighborhood, Galaxy accretion
LROC-derived 1 m Resolution Digital Elevation Model and Regolith Temperature Simulation of Banting Crater. The regolith temperature of the Moon is strongly influenced by direct solar radiation and multiple-scattered thermal radiation from the surrounding terrains. Accurate simulation of these processes requires high-resolution topography and a thermophysical framework. To this end, we constructed a 1 m resolution digital elevation model (DEM) of the Banting (BT) crater by fusing Lunar Reconnaissance Orbiter Camera (LROC) imagery with Lunar Orbiter Laser Altimeter data using the Integrated Software for Imagers and Spectrometers and Ames Stereo Pipeline software. Based on this high-resolution DEM, a 1D transient heat-conduction model was solved using the finite volume method to simulate the temporal and spatial evolution of the regolith temperature. The simulated illumination patterns agree with the LROC observations, confirming DEM reliability, and the temperature results show strong consistency with Diviner brightness temperature data. Within this validated modeling framework, we further evaluate the contribution of scattered solar radiation and thermal emission from Earth (SSRTEE) to the surface thermal balance. The analyses indicate that SSRTEE contributes less than 0.1 K to the regolith temperature at the BT site, far weaker than direct solar or multiple-scattered radiation. This result quantitatively confirms that Earth-induced radiative terms can be safely neglected in regolith temperature simulations for mid- and low-latitude lunar regions. This study provides a validated methodological framework for high-resolution lunar thermophysical modeling, which can support future surface environment investigations and landing-site assessments.

Keywords: Lunar craters, Lunar surface, Lunar geodesy
A Multiwavelength Study of Comet C/2022 E3 (ZTF): Complementary ALMA and JWST Investigations of Water and Methanol in Cometary Comae. Long-period comets, which are often considered to be representative of material in the protoplanetary disk that formed the solar system, are ideal to investigate the question of chemical inheritance in astronomy. Determining the chemistry of comets, both individually and as a population, has become of great importance in comparative studies against sources representative of evolutionary precursors to planetary systems. Contemporaneous observations of long-period comet C/2022 E3 (ZTF) were obtained with JWST and the Atacama Large Millimeter/submillimeter Array (ALMA) in early 2023 March. This work focuses on CH3OH measurements from both ALMA and JWST, as well as H2O measurements from JWST. Radiative transfer modeling of CH3OH and H2O was performed to investigate spatial variations in rotational temperature, column density, and production rates, as well as a comparison of derived values between the two telescopes. Most of the spatial distributions of the modeled values are centrally peaked, and the modeled values from JWST are all within the error bars of the average values from ALMA. C/2022 E3 (ZTF) also displays an enhancement in modeled rotational temperature in the antisunward direction that is shown to be statistically significant. Based on non-LTE radiative transfer modeling, the declining H2O rotational temperatures as a function of nucleocentric distance observed by JWST can be explained primarily as a result of rotational line cooling. The values derived in this work are in general agreement with single-dish millimeter-wave observations.

Keywords: Comets, Small Solar System bodies, Complex organic molecules, Astrochemistry
Measuring Rotation Periods in Crowded Star Clusters with TESS: A Proof of Concept with NGC 3532. The Transiting Exoplanet Survey Satellite (TESS) has observed nearly the entire sky, producing Full-Frame Images (FFIs) every 30 minutes (Cycles 1─2), 10 minutes (Cycles 3─4), and now 200 s (Cycle 5+), over 27 day sectors. Light curves extracted from FFIs can be used to measure stellar rotation periods (Prot) in nearby open clusters, and are well suited for studying low-mass stars (≲1.2 M⊙) younger than ≲1 Gyr, whose Prot are generally still ≤15 days. A challenge to exploiting TESS data fully is its 21″ pixel size, which can cause strong signals from one source to contaminate those of nearby stars, particularly in the crowded environments found, for example, in the more distant and/or richest clusters. We conducted a test with the young (≍350 Myr old), moderately distant (470 pc), and rich open cluster NGC 3532 (N⋆ &gt; 3000), which has an extensive Prot catalog from ground-based photometry, to examine the reliability of Prot obtained from TESS data. We recovered 69% of the literature periods from at least one of the three TESS cycles in which NGC 3532 was observed before any quality analysis. We then used all available TESS data for low-mass members of NGC 3532 and, applying a set of quality cuts that combined information from TESS and Gaia, measured Prot for 885 cluster stars, adding 706 new Prot to the existing catalog. We conclude that, when considered with appropriate caution, TESS data for stars in crowded fields can yield reliable Prot measurements.

Keywords: Open star clusters, Stellar rotation, Low mass stars
PaTRNet: Low-latency Spectral Energy Distribution Radio Frequency Interference Mitigation for FAST Pulsar Searches in NGC 6517. The increasing sensitivity and data volume of modern radio telescopes mean that mitigating radio frequency interference is critical for both accuracy and throughput. For the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), 2D image segmentation pipelines are often too slow at scale, while classical thresholding requires retuning for each site and epoch. We propose PaTRNet, a lightweight parallel Transformer-ResNet architecture operating on 1D spectral energy distribution representations obtained by time-axis accumulation, coupled with channel attention based on Kolmogorov─Arnold networks for dynamic cross-branch fusion. On real FAST data, PaTRNet attains an overall F1 of 0.888 with a per-slice inference latency of 3.04 ms, improving F1 by 14.6% over the strongest traditional baseline (ArPLS-ST) at 2.9 times lower latency, and running 20.6∼48.9 times faster than mainstream 2D segmentation networks while maintaining accuracy. Beyond offline metrics, we apply PaTRNet to FAST observations of the globular cluster NGC 6517 and run a standard PRESTO search on PaTRNet-processed data and raw data. Under identical downstream settings, PaTRNet increases the number of confirmed pulsars from five to six and recovers all five found in the raw-data search, indicating improved candidate visibility and completeness. Furthermore, we tested this pipeline system on the strong pulsar PSR J0837+0610 to ensure that genuine astrophysical signals are not mislabeled. *PaTRNet: SED RFI Mitigation for FAST.

Keywords: Radio telescopes, Astronomy data analysis
UOCS-XIX. A Multiwavelength Study of Open Cluster Trumpler 5: Cluster Properties and Exotic Populations. Trumpler 5 is a populous, intermediate-age (∼3 Gyr), metal-poor ([Fe/H] ∼ −0.4) open cluster, located at a distance of approximately ∼3050 pc. This is a well-studied cluster for its broadened main-sequence (MS) and blue straggler star (BSS) population. We present a UV-based analysis of the BSS and blue lurker (BL) candidates of this cluster using AstroSat/UVIT data along with Gaia DR3 data. We use a machine learning-based algorithm, ML-MOC, on Gaia DR3 data, and identify 3150 high-probability (P &gt; 0.6) cluster members, along with 305 moderate probability (0.2 &lt; P &lt; 0.6) cluster members. Among the cluster members, we identified 32 high-probability BSSs, 13 of which have counterparts in AstroSat/UVIT filters. Additionally, we find 11 MS stars with UVIT counterparts, which we term BL candidates. Upon examining the cumulative radial distribution of various stellar populations, we find the signature of mass segregation in the cluster, with massive stars, including the BSSs and the turnoff stars, found more centrally concentrated than low-mass stars. We investigate the properties of 10 BSS and six BL candidates through multiwavelength spectral energy distributions. We infer the presence of unresolved hot companions in a single BSS and four BL candidates. Our analysis suggests that the hot companion of the BSS is likely a hot subdwarf, whereas the companions of the BL candidates are likely low-mass white dwarfs. We conclude that these five BSS and BL candidates have formed via Case-A/Case-B mass-transfer events, with timescales ranging from ∼26 to 155 Myr.

Keywords: Open star clusters, Star clusters
Anatomy of Empirical Transit Spectra of Mars Based on TGO/NOMAD. Transit spectroscopy is a powerful tool for probing atmospheric structures of exoplanets. Accurately accounting for the effects of aerosols is key to reconstructing atmospheric properties from transit spectra, yet this remains a significant challenge. To advance this effort, it is invaluable to examine the spectral features of well-characterized planetary atmospheres. Here, we synthesize empirical transit spectra of Mars across different seasons based on data from the NOMAD's Solar Occultation channel on board ExoMars/TGO, which operates at wavelengths of 0.2─0.65 and 2─4 μm. In the generated empirical transit spectra, the atmosphere below 25 km is found to be largely opaque due to the presence of micron-sized dust and H2O ice clouds, both of which substantially weaken spectral features. The spectra exhibit CO2 absorption features at 2.7─2.8 μm and signatures of submicron-sized mesospheric H2O ice clouds around 3.1 μm, accompanied by a continuum slope. The amplitudes of these spectral features are found to vary with the Martian seasons, where the dust storms weaken the CO2 signatures and strengthen the H2O ice features, which serve as potential indicators of a dusty planet like Mars. If TRAPPIST-1f possessed a Mars-like atmospheric structure, both CO2 and H2O ice features would be detectable at a noise level of 3 ppm, a level likely beyond current observational capabilities. Nevertheless, the 3.1 μm feature produced by submicron-sized mesospheric H2O ice clouds offers a novel avenue for characterizing the atmospheres of habitable-zone exoplanets.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric dynamics, Interdisciplinary astronomy, Habitable planets, Exoplanet atmospheres
Solar Hegemony: M Dwarfs Are Unlikely to Host Observers Such As Ourselves. With no firm evidence for life beyond our solar system, inferences about the population of observers such as ourselves rest upon the Earth as a single input, at least for now. While the narrative of our home as a "humdrum" system has become ingrained in the public psyche via C. Sagan, there are at least two striking facts about our existence which we know are certainly unusual. First, the stelliferous period spans ∼10 Tyr—yet here we are living in the first 0.1% of that volume. Second, over three-quarters of all stars are low-mass M dwarfs, stars with no shortage of rocky habitable-zone planets—and yet, again, our existence defies this trend, previously dubbed the red sky paradox (RSP). Two plausible resolutions are that (a) stars below a certain mass, Mcrit, do not produce observers, and (b) planets have a truncated temporal window for observers, Twin, negating the longevity advantage of M dwarfs. We develop a Bayesian model that encompasses both data points and jointly explores the two resolutions covariantly. Our analysis reveals that (1) the hypothesis that these observations are mere luck is disfavored with an overwhelming Bayes factor of ≃1600; (2) some truncation of low-mass stars is indispensable, lowering Twin alone cannot well explain the observations; and (3) the most conservative limit on Mcrit occurs when fixing Twin = 10 Gyr, yielding Mcrit &gt; 0.34 M⊙ [0.74 M⊙] to 2σ [1σ]. Our work challenges the tacit assumption of M dwarfs being viable seats for observers and, indirectly, even life.

Keywords: Search for extraterrestrial intelligence, Astrobiology
The Solar Neighborhood. LIII. M Dwarf Twin Binaries—One in Five Twin Sibling Pairs Are Mismatched in Activity and/or Rotation. We report on a study of 36 pairs of "twin" M dwarfs in wide binaries and assess how similarly the stars behave. Stars in each twin pair have BP, RP, J, H, and Ks differing by &lt;0.10 mag, mass estimates matching within &lt;3%, and presumably the same age and composition. We utilize short- and long-term photometry, multiepoch spectroscopy, and archival data to measure rotation periods, photometric activity levels, and Hα equivalent widths for many systems. Speckle imaging, radial velocities, and long-term astrometry are used to identify unresolved companions, yielding three systems with unseen components. Among the 33 remaining twin systems, numerous remarkable pairs show nearly identical rotation rates and activity levels between their twin components, including cases throughout the lower main sequence and across a broad range of rotation─activity parameter space. In contrast, mismatches with &gt;25% differences exist in rotation period for  21%−7%+14%  of twin pairs, in rotation amplitude for  67%−15%+10%  of pairs, in multiyear photometric variability for  33%−9%+12%  of pairs, and in Hα activity for  21%−6%+9%  of pairs, with fully convective systems generally mismatched more often. Thus, roughly one out of five M dwarf twin sets does not match in rotation and/or activity despite otherwise identical fundamental parameters. Furthermore, we compile three key systems showing larger relative active/inactive Hα mismatches. We propose the various mismatches likely stem from factors such as dynamo stochasticity, activity cycles, formative disk aspects, and/or star─planet interactions, depending on the system. These well-vetted twins offer ripe targets for many future investigations.

Keywords: M dwarf stars, Solar neighborhood, Stellar activity, Wide binary stars, Stellar rotation, Stellar evolution
Analysis of Karin and Koronis2 Asteroid Families: New Findings and Challenges. We use our home catalog of the asteroid proper elements to study the Karin family. The hierarchical clustering method provides formal identification with 3863 members, but this set also includes objects from the neighboring Koronis2 and Kuitaisi families, as well as interlopers originating from the much older Koronis family. By tracking the trajectories of cluster objects backward in time, we identified 2161 asteroids whose orbits converged with that of their parent body (832) Karin at 5.72 ± 0.09 Mya (95% C.L.). This method of calculating the family's age is based on a novel convergence metric that is directly related to the velocities at which fragments were ejected from (832) Karin. We analyze the extent to which members ≤1.5 km in diameter had drifted in semimajor axis due to Yarkovsky thermal forces and find it reflects the tilt of their rotation poles away from the ecliptic, recording the influence of the YORP torque. Karin's size frequency distribution in the ≃(0.8─3) km range follows a power law with a cumulative slope index −3.20 ± 0.01. Removing members of the Karin family from the original group, we examine the Koronis2 family, whose members are associated with (158) Koronis. We find it difficult for large members of the Koronis2 family to converge with the orbit of (158) Koronis within its previously estimated age of 7.6 Myr. Achieving such convergence would require the Koronis2 family to be older than 10 Myr, but our result must be verified with a direct numerical approach in the future.

Keywords: Asteroids
Eight Phase-step δ Scuti Variables in TESS Data. Analysis of the previously classified delta Scuti variable star MW Camelopardalis using data from the Transiting Exoplanet Survey Satellite sparked a deeper inquiry due to unexpected patterns within the target's observed − calculated (O − C) diagram. The shape could be seen as either a saw-toothed pattern or a set of steps. The pattern was found to be replicated in the O − C diagrams of seven additional targets: TIC 17931346, TIC 44845403, TIC 123580083, TIC 173503902, TIC 302394816, TIC 194944219m and TIC 396465600. The Q value for the targets, their position in the δ Scuti star Leavitt Law, and their location in the instability strip show these objects to be low-mass, fundamental mode pulsators. Seven of the eight stars fill the full range between the blue and red edges of the fundamental-mode instability strip.

Keywords: Short period variable stars, Delta Scuti variable stars, Pulsating variable stars
Spectroscopic Characterization of WD J000801.25-350450 and Its Two Comoving Companions. We present new spectroscopic data for Gaia DR3 2309499817384726016 (WD 0008-350A) and its two wide, comoving, low-mass companions. We confirm the white dwarf is a hydrogen rich DA, with Teff = 6200 ± 90 K and a mass of 0.63 ± 0.03 M⊙, close to that of the average white dwarf. Near-infrared spectra of the two stellar companions to WD 0008-350A reveal that the inner companion is an M dwarf, exhibiting a spectral type of M8. Furthermore, the outer companion is identified as a possible M6 + M9 binary. This paper examines the evidence which suggests the system may be quadruple.

Keywords: M dwarf stars, Multiple stars, DA stars
Early Planet Formation in Embedded Disks (eDisk). XIX. Structures of Molecular Outflows. As part of the ALMA Large Program "Early Planet Formation in Embedded Disks," 12CO (2─1) was observed towards 19 nearby low-mass protostars. Of these objects, 15 sources are found to show molecular outflow emission. Based on their morphological and kinematical structures, the CO outflows are classified into three types: a wind-driven shell, where ambient material is swept up by a wide-angle wind from the star, a bow shock, and a slow disk wind, which is a conical or parabolic flow with onion-like velocity structure. We categorize 11 outflows as a slow disk wind, 7 as a wind-driven shell, and 1 as a bow shock. Four of these outflows were found to show signs of both slow disk wind and wind-driven shell characteristics. Five objects show misalignment between the red- and blueshifted outflows. Seven objects show significant misalignment between the outflow axis (either or both of the red- and blueshifted outflows) and the minor axis of the dust continuum emission around the protostar. For the objects showing wind-driven shell emission, we compare simple parametrized models with the observations to derive physical properties of the observed shells, such as their dynamical ages. This shows evidence of a time variability in the outflows, such as changes in their direction. In some objects, large differences are seen between the properties of the red- and blueshifted outflows, possibly indicating differences in the properties of the ambient medium with which the outflow interacts.

Keywords: Millimeter astronomy, Stellar jets, Star formation, CO line emission