Sazuna/UAT_keywords huggingface dataset:
A Warm Massive Pair of Planets around TOI-1232 Revealed with Transit-timing Variations and Doppler Spectroscopy. TOI-1232 is a G dwarf star with a mass of  1.06−0.06+0.07M⊙ , a radius of 1.07 ± 0.05 R⊙, and a slightly higher metallicity than solar of Fe/H = 0.18 ± 0.05. The star hosts a transiting warm Jovian-mass planet, TOI-1232 b, with an orbital period of  Pb=14.256−0.001+0.001  days, identified with data from multiple sectors of the TESS space telescope. The TESS light curve of TOI-1232 is complex, as it is contaminated by a background eclipsing binary with a period of 1.37 days. TOI-1232 b was firmly confirmed by ground-based transit follow-up campaigns from the Las Cumbres, Hazelwood, Brierfield, and ASTEP observatories. Additionally, the TESS transits of TOI-1232 b exhibit strong transit-timing variations (TTVs) with a superperiod of 235.5 ± 0.7 days and a semiamplitude of 27 minutes. Radial velocity (RV) follow-up with the FEROS spectrograph confirms the planetary nature of the transiting candidate, while a self-consistent N-body analysis of RVs and TTVs pinpoints the presence of a second outer Saturn-mass companion, TOI-1232 c with a period of  Pc=30.356−0.012+0.010  days. The TOI-1232 warm-giant system is particularly important due to the evidence of two massive planets that reside near the 2:1 commensurability but are not locked in a mean-motion resonance. Thanks to TESS, we have revealed a handful of these rare systems. Hence, TOI-1232 is an important addition to understanding the formation and dynamical evolution of such compact, massive, warm giant planets. *Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere under MPG programmes 0102.A-9006, 0103.A-9008, 0104.A-9007.

Keywords: Exoplanet dynamics, Radial velocity, Transit photometry, Transit timing variation method
Paving the Road to the Habitable Worlds Observatory with High-resolution Imaging. I. New and Archival Speckle Observations of Potential HWO Target Stars. One of the key goals of the Habitable Worlds Observatory (HWO) is to directly image about 25 potentially habitable exoplanets and determine their properties. This challenge will require a large survey of nearby, bright stars: ∼100 according to the Astro2020 Decadal Survey. To ensure the success of the mission and to help guide design decisions, the stellar multiplicity of the target stars must be well-understood. To this end, we present optical speckle imaging of stars in the NASA Exoplanet Exploration Program provisional HWO star list, which is currently the Tier 1 target list for the HWO Target Stars and Systems Sub-Working Group. We obtained new observations using 'Alopeke and Zorro at Gemini Observatory and queried the Exoplanet Follow-up Observing Program Archive for archival observations, resulting in speckle imaging data for 80 of the 164 stars. We confirmed one candidate companion detected previously by Gaia (HD 90089) and obtained an ambiguous detection of a known companion (HD 212330). To examine our sensitivity to companions, we simulated stellar companions down to ∼0.1 M⊙ for each target and found that 75%─85% would be detected in our speckle images; the remaining simulated companions are either too faint or too close-in, and will require follow-up using other methods such as long-term spectroscopic measurements and space-based techniques. This work represents a first step toward surveying potential HWO targets for close-in stellar companions and helping to inform the target selection process for the HWO direct-imaging survey, bringing us closer toward the discovery of potential habitable worlds.

Keywords: Observational astronomy, Stellar astronomy, Multiple stars, Exoplanet astronomy
The Solar Neighborhood LV: Spectral Characterization of an Equatorial Sample of 580 K Dwarfs. We present a spectroscopic characterization of 580 K dwarfs within 33 pc, observed with the CHIRON echelle spectrograph (R = 80,000) on the SMARTS 1.5 m telescope. This volume-limited sample is part of the RKSTAR survey of ∼4400 K dwarf primaries within 50 pc. Using Empirical SpecMatch and the diagnostic lines Hα (6562.8 Å) and Li I (6707.8 Å), we derive stellar properties, activity status, and age indicators calibrated against 35 benchmark K dwarfs with ages from 20 Myr to 5 Gyr. We find that 7.4% (43 stars) exhibit signatures of youth and/or chromospheric activity: 19 stars show lithium absorption indicating ages &lt;1 Gyr, and 36 display Hα emission. Kinematic analysis using BANYAN Σ identifies eight additional young stars through membership in the AB Doradus moving group and the Hyades cluster, bringing the total young/active population to 8.8% (51 stars). Stellar parameters span 3600─5500 K in Teff, −0.60 to +0.55 dex in [Fe/H], and &lt;10 to &gt;25 km s−1 in  vsini . A metal-poor population ([Fe/H] ≤ −0.50 dex) comprises 4% of the sample. Galactic kinematics place 80% in the thin disk and 18.4% in the thick disk, with one halo member (HD 134439). Young and active stars are predominantly thin disk members, with two thick-disk exceptions. Cross-matching with NASA's Exoplanet Archive reveals only 7.5% (44 stars) host confirmed planets as of 2025 July. Our results identify 529 mature, inactive K dwarfs as prime targets for terrestrial planet searches, providing a crucial resource for exoplanet habitability studies in the solar neighborhood.

Keywords: Solar nebulae, Late-type stars, Stellar ages, Solar neighborhood, Spectroscopy
Status and Performance of the Balanced Superconductor-insulator-superconductor Receivers for the Leighton Chajnantor Telescope. In this paper, we report on the current status and performance of the balanced superconductor-insulator-superconductor (SIS) receiver suite developed for the Leighton Chajnantor Telescope (LCT). Currently, Shanghai Normal University (ShNU) together with Caltech and Universidad de Concepción are collaborating on the LCT program, which aims to relocate the Caltech Submillimeter Observatory (CSO) telescope from Mauna Kea, Hawaii to the Chajnantor Plateau in Chile. A suite of balanced SIS receivers exhibiting excellent sensitivity, covering the 180─720 GHz atmospheric windows, will be deployed as first-light instruments to facilitate high-resolution spectral line observations. The 230/460 GHz receiver pair was previously commissioned and operated at the CSO until its closure. In contrast, the 345/650 GHz receiver pairs had not been commissioned or tested prior to this work. Recently, these balanced SIS receivers were assembled and characterized for the first time in the submillimeter laboratory at ShNU. This paper presents a comprehensive overview of the receiver system and discusses the detailed experimental results obtained from these characterization measurements.

Keywords: Submillimeter astronomy, Heterodyne receivers, Radio telescopes
The Effect of Massive Trans-Neptunian Objects in the Long-term Evolution and Leakage Rates of Neptune's 3:2 and 2:1 Mean Motion Resonances. The current populations trapped in Neptune's main mean motion resonances in the Kuiper Belt, Plutinos in the 3:2 and Twotinos in the 2:1, contain some of the best-characterized minor objects in the solar system, given their dynamical importance. In particular, Twotinos may hide evidence of Neptune's early migration. However, these populations vary in time, declining at a rate that has not previously been clearly established. In this work, we use numerical simulations to study the long-term evolution of the Plutino and Twotino populations. We use two data sources: the most up-to-date observations and the theoretical debiased model of the Kuiper Belt known as L7. In addition to studying the giant planets' effect on these populations over 4 Gyr, we analyze the additional impact produced by the ten most massive trans-Neptunian objects (TNOs) trapped in these resonances, as well as the effect of Pluto on the 2:1 population. We find that the decay rate in each resonance can be modeled as a stochastic process well described by an exponential decay with an offset determined by an underlying long-term stable population. The most massive TNOs, particularly Pluto, influence this decay rate significantly, as expected for the 3:2 resonance. Remarkably, Pluto also strongly influences the 2:1 resonance's evolution.

Keywords: Solar system evolution, Pluto, Resonant Kuiper belt objects, Trans-Neptunian objects
JWST COMPASS: Insights into the Systematic Noise Properties of NIRSpec/G395H from a Uniform Reanalysis of Seven Transmission Spectra. JWST has already observed near-infrared transmission spectra of over a dozen super-Earths and sub-Neptunes. While some observations have allowed astronomers to characterize sub-Neptunes in unprecedented detail, small feature amplitudes and poorly understood systematics have led to ambiguous results for others. Using the first seven targets from the COMPASS program, which will survey 12 small planets using NIRSpec/G395H, we investigate timeseries systematics. We implement a model that uses the principle components of the normalized pixel fluxes to account for variations in the shape and position of the spectral trace. We find that observations with a smaller number of groups-per-integration benefit most profoundly from the use of this model, and that systematics are particularly strong between 2.8 and 3.5 μm. Despite these systematics, pandexo is a relatively accurate predictor of the precision of the spectra, with real error bars on average 5% larger in NRS1 and 12% larger in NRS2 than predicted. We compute new limits on metallicity and opaque pressure level for each target and compare these to previous results from the COMPASS program. Next, we coadd spectra from multiple targets to reduce the effective noise in the combined spectra in hopes of detecting transmission features in common between the targets, but this exercise does not yield compelling evidence of any signals. We find that a handful of additional transits are sufficient to break the degeneracy between metallicity and aerosols for the majority of our targets, pointing towards the possibility of unraveling the mysteries of these worlds with future allocations of JWST time.

Keywords: Exoplanets, Super Earths, James Webb Space Telescope, Mini Neptunes, Exoplanet atmospheres
Unveiling Ionized Jet Morphologies: Subarcsecond VLA Observations of Compact Radio Sources. We present subarcsecond (θ ∼ 0 .″ 1) resolution VLA 1.3 cm continuum and 22.2 GHz H2O maser observations toward 15 compact radio continuum sources with rising spectral index and eight string-like radio continuum structures in the V. Rosero et al. survey. Three different morphologies are observed: elongated or double-peak string-like structure (6 out of 23 cases), a collection of distinct continuum peaks (4 out of 23 cases), and single compact sources (13 out of 23 cases). The majority of H2O maser spots detected are within a sky-projected distance of ∼5000 au from the radio continuum peaks and tend to be well aligned and distributed in an elongated structure when more than three spots are observed. We generally recover less emission than V. Rosero et al., which together with the fact that more than half of the jet candidates in our survey appear mostly compact, suggest core/halo shock structures even on small scales. We also detected proper motion in 10 cases and measured an average projected velocity of approximately 120 km s−1. Radio brightness variability is detected in at least two cases, possibly due to weak accretion bursts. This work, together with our previous molecular jet study, provides further evidence that support the main source of ionization in the studied sources is shocks, yet collimation is only observed in 4 cases. We conclude that the available data supports the thermal jet classification of seven sources, and the ionized jet interpretation is further supported in 16 sources.

Keywords: Jets, Radio jets, Star forming regions, Massive stars, Water masers, Young stellar objects, Star formation, Astrophysical masers, Radio astronomy
JWST COMPASS: NIRSpec/G395H Transmission Observations of the Sub-Neptune HD 15337 c. We present the 3─5 μm transmission spectrum of HD 15337 c (TOI-402.02), a sub-Neptune (2.526 R⊕, 6.792 M⊕, Teq ∼ 656 K) around a K1V star observed as part of the JWST COMPASS program. We reduce two observations with two pipelines and find consistent transmission spectra. The resulting median precisions in 30 pixel spectroscopic bins for visit 1 are ∼40 ppm and ∼70 ppm and for visit 2 are ∼30 ppm and ∼54 ppm for NRS1 and NRS2, respectively. We attribute the differing precisions to the lack of adequate pre-transit baseline in visit 1 from an early transit arrival caused by previously undetected transit timing variations (TTVs), hinting at a potential exterior companion. Our median JWST timing precision is 10 s, revealing TTVs &gt;20 minutes when combined with previous TESS and CHEOPS data, highlighting JWST's TTV measurement capabilities. The transmission spectrum of HD 15337 c is featureless and can best be described by a step function with an offset between the NRS1 and NRS2 detectors, likely caused by instrumental systematics. From thermochemical equilibrium retrievals we find that, to &gt;3σ, the data can rule out atmospheres with metallicities &lt;600 or &lt;310 × solar, depending on the reduction, for opaque pressures greater than a few millibars. HD 15337 c joins other sub-Neptunes with similar masses, radii, and temperatures in possessing a featureless transmission spectrum indicative of high metallicity and/or high-altitude aerosols and adds support to recent studies showing that aerosol opacity reaches a maximum for planets with equilibrium temperatures of 500─700 K.

Keywords: Exoplanet atmospheric composition , Infrared spectroscopy, Exoplanet atmospheres, Exoplanets
The Pre-He White Dwarfs in Eclipsing Binaries. V. TIC 399725538. We present echelle spectra of TIC 399725538 obtained in Korea and Thailand to investigate the physical properties and evolutionary scenarios of EL CVn-type binaries. The time-series spectra yielded the radial velocities (RVs) of the primary component and its atmospheric parameters, Teff,A = 7194 ± 70 K and  vAsini=68±9  km s−1. Joint modeling of our RVs and the archival TESS data provided component masses of MA = 1.930 ± 0.054 M⊙and MB = 0.211 ± 0.005 M⊙, radii of RA = 1.922 ± 0.020 R⊙and RB = 0.207 ± 0.005 R⊙, and luminosities of LA = 8.87 ± 0.39 L⊙and LB = 0.546 ± 0.034 L⊙. The surface gravity and distance derived from this modeling are consistent with the model-independent  loggB  obtained from the direct observables and with the Gaia distance. The third light of l3 = 0.136 ± 0.003 comes mainly from two neighboring stars, TIC 399725539 and TIC 399725544. Comparison with stellar models indicates that TIC 399725538 A lies within the instability region of δ Sct−γ Dor hybrids, whereas its extremely low-mass companion is markedly underluminous compared to theoretical white-dwarf (WD) counterparts. Multifrequency analysis of the binary-subtracted residual lights revealed three significant signals, two of which correspond to aliases at two and four times the dominant frequency f1 = 0.0848 day−1. The f1 frequency is likely a γ Dor-type pulsation arising from the brighter A component, though further confirmation is required. Our results demonstrate that TIC 399725538 is a short-period EL CVn system belonging to the thick-disk population, consisting of a main-sequence γ Dor pulsator and a helium-core WD precursor formed through stable mass transfer.

Keywords: Stellar pulsations, Fundamental parameters of stars, White dwarf stars, Spectroscopic binary stars, Eclipsing binary stars, Gamma Doradus variable stars, Stellar evolution
Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE). IV. Analyzing CO<SUB>2</SUB> Detections in the Near-IR to Determine the Long-wavelength Cutoff for the Habitable Worlds Observatory Coronagraph. We present our analysis of how the detectability of carbon dioxide (CO2) on an Earth-like planet varies with respect to signal-to-noise ratio (SNR), wavelength, and molecular abundance. Using the Bayesian Analysis for Remote Biosignature Identification on exoEarths methodology, we can determine the optimal long-wavelength cutoff for the future Habitable Worlds Observatory coronagraph. We test 25 evenly spaced 20% bandpasses between 0.8 and 2.0 μm, and simulate data spanning a range of SNRs and molecular abundance to analyze the relationship between wavelength and detectability for different planetary archetypes. We examine abundance levels from varying Earth epochs and a Venus-like archetype to investigate how detectability would change throughout the evolution of a rocky planet. Here, we present our results on the planetary conditions and technological requirements to strongly detect CO2. In addition, we analyze the degeneracy of CO2 with carbon monoxide (CO), methane (CH4), and water (H2O). We determine that any abundance of CO does not achieve strong detections and that CH4 and H2O play a pivotal role in the ability to detect CO2. We conclude that the optimal long-wavelength cutoff for the Habitable Worlds Observatory coronagraph should be 1.68 μm.

Keywords: Astrobiology, Exoplanets
The MIRI Excesses Around Degenerates (MEAD) Survey. II. A Probable Planet Detected via IR Excess around WD 0644+025. The MIRI Excesses Around Degenerates (MEAD) Survey is a Cycle 2 JWST program designed to image nearby white dwarfs with MIRI at 10 and 15 μm. This survey targeted 56 white dwarfs within 25 pc to search for mid-infrared excesses, flux deficits from collision-induced absorption, and resolved substellar companions. In this paper we present our analysis of WD 0644+025, an unusually massive white dwarf (0.95 M⊙) and the MEAD target exhibiting the most significant mid-infrared excess. The observed JWST MIRI photometry shows a 7.3σ excess at 15 μm and a 3.6σ excess at 10 μm, which may be associated with either a planetary companion or a circumstellar dust disk. This excess corresponds to a companion mass of 6.8MJup (Teff = 261 ±9 K) with orbital distance &lt;11.8 au, although substantially lower masses are possible if we consider a closely orbiting isolated companion. No spatially resolved sources are detected within 200 au, with contrast curve analysis excluding planets more massive than 2MJup beyond ∼12 au. Metal pollution is confirmed in both archival Keck HIRES spectra from 1999 and new observations from 2025, with no evidence suggesting that the accretion rate has substantially changed over the decades. We explore possible dust disk morphologies to describe the observed IR excess and find that traditional debris disks struggle to fit our data. WD 0644+025 thus represents a compelling case study in the growing population of white dwarfs with cold infrared excesses and highlights JWST's ability to probe planetary system remnants inaccessible to prior infrared observatories.

Keywords: High contrast techniques, White dwarf stars, Exoplanet astronomy, Direct imaging, Photometry, Circumstellar dust
Nine Years of UVIT: Assessing Sensitivity Variation. The Ultra-Violet Imaging Telescope (UVIT) is one of the five payloads on board the first Indian multiwavelength astronomical observatory, AstroSat, launched by the Indian Space Research Organisation on 2015 September 28. UVIT, designed for simultaneous imaging in the far-ultraviolet (FUV; 1300−1800 Å) and near-ultraviolet (NUV; 2000−3000 Å) channels, has completed 9 yr in orbit in 2024 despite the failure of the NUV channel in 2018. As the FUV optics is subject to possible reduction in sensitivity due to microscopic amounts of contaminants, we used the FUV data acquired by UVIT over the past 9 yr on the open cluster NGC 188 and the white dwarf HZ 4 to study sensitivity variations in the UVIT FUV channel. Our findings indicate no significant reduction in the sensitivity of the FUV channel over the last 9 yr, with no significant episodic variations due to unknown causes.

Keywords: Open star clusters, Ultraviolet telescopes, Ultraviolet observatories
Fringe Detection in the Lunar Orbit VLBI Experiment: The Initial Clock Search. We present the design and implementation of a fringe detection pipeline for the Lunar Orbit VLBI Experiment (LOVEX) on board China's Queqiao-2 cislunar relay satellite. To address the challenge posed by limited space─ground time synchronization accuracy, we developed a dedicated initial clock offset search scheme based on a modified version of the Chinese VLBI Network software correlator. Key features of the pipeline include raw data validation, wide-range clock offset search, iterative fringe fitting, and GPU-accelerated processing. The pipeline was successfully applied to the initial clock offset determination in LOVEX observations. In particular, we report the detection of fringes for blazar AO0235+164 in the s5123m session, where a projected baseline length of 5.5 Earth diameters was achieved. We further discuss technical approaches for enhancing sensitivity to weak signals, with an emphasis on the need for advanced phase calibration techniques. The potential application of tensor core acceleration is also discussed.

Keywords: Space telescopes, GPU computing, Very long baseline interferometry, Radio astronomy
The Solar Neighborhood LIV: 54 Orbits of M Dwarf Multiples within 30 pc with Speckle Interferometry at SOAR. We present 1066 speckle measurements of M dwarf multiples observed over 2021─2024, all taken with HRCam on the Southern Astrophysical Research 4.1 m telescope. Among these, 900 observations resolve companions in 212 pairs, with separations spanning 17 mas to 3 .″ 4 and brightness differences ranging from 0 to 4.9 mag in the I filter. We have characterized the orbits of 54 of these companions, spanning periods of 0.67─30 yr, by combining our data with literature astrometry, radial velocities, and, in four cases, Hipparcos─Gaia accelerations. Among the orbits presented here are 28 that are the first-ever such characterizations for their systems and 26 that revise previously published orbits, thus providing a significant update to the observed dynamics of M dwarfs in the solar neighborhood. From these orbits, we provide new and updated dynamical total masses for these systems, precise to 0.7%─7% in nearly all cases. Future mass derivations for components in these systems will contribute to efforts in refining the mass─luminosity relation for the smallest stars and will enhance investigations of age, magnetism, and metallicity effects on luminosities at a given mass.

Keywords: M dwarf stars, Binary stars, Astrometric binary stars, Low mass stars, Astrometry, Speckle interferometry