Sazuna/UAT_keywords huggingface dataset:
Survey of S-type AGB Stars Using the KVN Four-band Receiving System: SMASTES II. We present the observational results of Simultaneous Multi-mAser Survey Toward Evolved Stars (SMASTES) II for 150 S-type asymptotic giant branch stars. Observations have been performed from 2023 September to 2024 March using the upgraded wide four-band (22/43/86/129 GHz) receiving system of the Korean VLBI Network. For simultaneous observations, 19 molecular lines of H2O and multitransitions of SiO masers including several thermal lines were set up together. H2O maser was not detected from any stars among 150 S-type stars. For SiO v = 1: J = 1─0, J = 2─1, and J = 3─2 masers were detected from nine, thirteen, and six stars, respectively. For SiO v = 2: J = 1─0, J = 2─1, and J = 3─2 masers were detected from five, two, and two stars, respectively. In particular, for v = 1: J = 1─0, J = 2─1, and J = 3─2 masers were all detected from five stars. For SiO v = 0: J = 1─0, J = 2─1, and J = 3─2 lines in ground vibrational state were detected from five, six, and seven stars, respectively, including the 29SiO v = 0: J = 1─0 and J = 2─1 lines. For SiO v = 0: J = 1─0, J = 2─1, and J = 3─2 lines were detected in more stars at higher rotational transition lines. The carbon-bearing molecule HCN was detected from four stars. Based on these observational results, we perform statistical analyses on detection rates of maser and thermal lines, maser properties, and kinematics comparing with the results of M-type stars (SMASTES I). The characteristics of maser properties are investigated in the IRAS two-color diagram in relation to the evolutionary stage.

Keywords: Interstellar thermal emission, Asymptotic giant branch stars, Astrophysical masers, Late stellar evolution
Procedures for Constraining Robotic Fiber Positioning for Highly Multiplexed Spectroscopic Surveys: The Case of FPS for SDSS-V. One crucial aspect of planning any large scale astronomical survey is constructing an observing strategy that maximizes reduced data quality. This is especially important for surveys that are rather heterogeneous and broad-ranging in their science goals. The Sloan Digital Sky Survey V (SDSS-V), which now utilizes the Focal Plane System (FPS) to robotically place fibers that feed the spectrographs, certainly meets these criteria. The addition of the FPS facilitates an increase in survey efficiency, number of targets, and target diversity, but also means the positions of fibers must be constrained to allow for simultaneous observations of sometimes competing programs. The constraints on the positions of the fibers are clearly driven by properties of the science targets, e.g., the type of target, brightness of the target, position of the target relative to others in the field, etc. The parameters used to describe these constraints will also depend on the intended science goal of the observation, which will vary with the types of objects requested for the particular observation and the planned sky conditions for the observation. In this work, we detail the SDSS-V data collection scenarios, which consist of sets of parameters that serve as the framework for constraining fiber placements. The numerical values of these parameters were set based on either past experiences or from a series of new tests, which we describe in detail here. These parameters allow a survey like SDSS-V to be algorithmically planned to maximize the science output, while guaranteeing data quality throughout its operation.

Keywords: Surveys, Sky surveys, Spectroscopy
Precise Physical Parameters, Habitability, and Orbital Stability of Sun-like SB2 Systems: HD 130669, HD 184467, HD 191854, and HD 214222. This work analyzes four Sun-like double-lined spectroscopic binary systems by combining visual and spectroscopic observational data with Al-Wardat's atmospheric modeling method to accurately determine their fundamental parameters. For each system, we determine stellar masses, orbital parallaxes, effective temperatures, spectral types, semimajor axes, and eccentricities with high precision, resolving discrepancies between astrometric and spectroscopic measurements. Moreover, we assess the potential for stable planetary orbits in these systems. We also calculate habitable zones around these binaries based on the orbital evolution of planetary orbits. These systems may represent promising targets for future extrasolar planet searches around Sun-like stars due to their robust physical and orbital parameters, which can be used to determine planetary habitability and stability.

Keywords: Spectroscopic binary stars, Visual binary stars, Habitable zone
The Interpolation Constraint in the RV Analysis of M Dwarfs Using Empirical Templates. Precise radial velocity (pRV) measurements of M dwarfs in the near-infrared rely on empirical templates due to the lack of accurate stellar spectral models in this regime. Templates are assumed to approximate the true spectrum when constructed from many observations or in the high signal-to-noise limit. We develop a numerical simulation that generates SpectroPolarimètre InfraRouge (SPIRou)-like pRV observations from PHOENIX spectra, constructs empirical templates, and estimates radial velocities (RVs). This simulation solely considers photon noise and evaluates when empirical templates remain reliable for pRV analysis. Our results reveal a previously unrecognized noise source in templates created from stacking registered observations, establishing a noise floor for such template-based pRV measurements. We find that these templates inherently include distortions in stellar line shapes due to imperfect interpolation at the detector's sampling resolution. The magnitude of this interpolation error depends on sampling resolution and RV content. Consequently, for stars with higher RV content, such as cooler M dwarfs, interpolation noise has a larger relative impact, making their performance comparable to hotter M dwarfs when using detectors with low sampling. For a typical M4V star, SPIRou's spectral and sampling resolution imposes an RV uncertainty floor of 0.5─0.8 m s−1, independent of the star's magnitude or the telescope's aperture. These findings reveal a limitation of template-based pRV methods, underscoring the need for improved spectral modeling and better-than-Nyquist detector sampling to reach the next level of RV precision.

Keywords: Exoplanet detection methods, Radial velocity
No Giant Planets in the Eta Cassiopeiae System: Dynamical Implications of a Wide Binary Companion. Given the vast number of stars that exist within binary systems, it remains important to explore the effect of binary star environments on the formation and evolution of exoplanetary systems. Nearby binaries provide opportunities to characterize their properties and orbits through a combination of radial velocities, astrometry, and direct imaging. Eta Cassiopeiae is a bright, well-known binary system for which recent observations have provided greatly improved stellar masses and orbital parameters. We present additional radial velocity data that are used to perform an injection-recovery analysis for potential planetary signatures. We further provide a detailed dynamical study that explores the viability of planetary orbits throughout the system. Our combined analysis shows that giant planets are significantly ruled out for the system, and indeed no planetary orbits are viable beyond ∼8 au of the primary star. However, terrestrial planets may yet exist within the habitable zone where orbits can remain long-term stable. We discuss the implications of these results, highlighting the effect of wide binary companions on giant planet formation, and the consequences for occurrence rates and planetary habitability.

Keywords: Exoplanet dynamics, Binary stars, Exoplanets, Orbits, Exoplanet systems, Orbital evolution, Exoplanet astronomy, Habitable zone, Habitable planets
Bioverse: Assessing the Ability of Direct Imaging Surveys to Empirically Constrain the Habitable Zone via Trends in Albedo. Will future direct imaging missions such as NASA's upcoming Habitable Worlds Observatory (HWO) be able to understand Earth-sized planets as a population? In this study, we simulate the ability of space-based coronagraphy missions to uncover trends in planetary albedo as a function of instellation, and potentially constrain the boundaries of the habitable zone (HZ). We adapt the Bioverse statistical comparative planetology framework to simulate the scientific output of possible designs for HWO. With this tool, we generate a synthetic planetary population with injected population-level trends in albedo and simulate the observability of planets. We then determine the statistical power to which these trends can be recovered as a function of the strength of the injected trend and the sample size of Earth-sized planets in the habitable zone (exoEarths). The strongest trends in albedo require a sample size of roughly 25─30 exoEarths to recover with high confidence. However, for weaker albedo trends, the required number of planets increases rapidly. If a mission is designed to meet the Decadal Survey's requirement of 25 exoEarths, it would be able to recover very strong trends in albedo associated with the HZ, but would struggle to confidently detect weaker trends. We explore multiple strategies to increase one's ability to recover weak trends, such as reducing the uncertainties in observables, incorporating additional observables such as planet colors, and obtaining direct constraints on planetary albedo from full spectral retrievals.

Keywords: Exoplanets, Astrostatistics, Astrobiology, Habitable zone, Habitable planets, Exoplanet atmospheres
Direct Imaging Explorations for Companions from the Subaru/IRD Strategic Program II; Discovery of a Brown-dwarf Companion around a Nearby Mid-M-dwarf LSPM J1446+4633. We report the discovery of a new directly imaged brown-dwarf companion with Keck/NIRC2+pyWFS around a nearby mid-type M-dwarf LSPM J1446+4633 (hereafter J1446). The  L' -band contrast (4.5 × 10−3) is consistent with a ∼20─60 MJup object at 1─10 Gyr and our two-epoch NIRC2 data suggest a ∼30% (∼3.1σ) variability in its  L' -band flux. We incorporated Gaia DR3 non-single-star catalog into the orbital fitting by combining the Subaru/IRD radial velocity monitoring results, NIRC2 direct imaging (DI) results, and Gaia proper motion acceleration. As a result, we derive  59.8−1.4+1.5MJup  and ≍4.3 au for the dynamical mass and the semimajor axis of the companion J1446B, respectively. J1446B is one of the intriguing late-T dwarfs showing variability at  L' -band for future atmospheric studies with the constrained dynamical mass. Because the J1446 system is accessible with various observation techniques such as astrometry, DI, and high-resolution spectroscopy including radial velocity measurement, it has a potential as a great benchmark system to improve our understanding for cool dwarfs.

Keywords: Radial velocity, Brown dwarfs, Direct imaging, Gaia
New Orbital Constraints for YSES 1 b and HR 2562 B from High-Precision Astrometry and Planetary Radial Velocities. We present new VLTI/GRAVITY astrometry and updated orbit fits for the directly imaged companions YSES 1 b and HR 2562 B, substellar objects straddling the planet─brown-dwarf boundary. Using high-precision astrometry, radial velocity data, and proper motions, we derive revised orbital parameters with orbitize!. For YSES 1 b, the inclusion of GRAVITY astrometry and a relative radial velocity measurement from Y. Zhang et al. (2024) overcomes the traditional challenge of constraining eccentricities for distant companions, enabling the first orbit fit and yielding a constrained eccentricity of 0.44 ± 0.20. This represents the first full orbit fit for the system. Additionally, we calculate a median line-of-sight stellar obliquity of  12−8+11  deg, providing further insight into the system's dynamical architecture. For HR 2562 B, our analysis agrees with S. Y. Zhang et al., confirming a low-eccentricity orbit (0.34 ± 0.20) and an inclination of 87 ± 1 deg. We find HR 2562 B's orbit to be nearly coplanar with the debris disk, with a mutual inclination of 3.7 ± 0.3 deg. For both YSES 1 b and HR 2562 B the lower eccentricities favor an in situ formation scenario over extreme scattering or cloud fragmentation. ∗Based on observations collected at the European Southern Observatory under ESO programmes 109.238N.002, 110.23U4.001, 109.238N.004, 113.26QU.001, 1104.C-0651(B), 109.238N.002, 109.238N.004, 60.A-9102(J), and 114.27UV.001.

Keywords: Exoplanet detection methods, Direct imaging
Ten Aligned Orbits: Planet Migration in the Era of JWST and Ariel. Understanding the diverse formation and migration pathways that shape exoplanetary systems requires characterizing both their atmospheric properties and their orbital dynamics. A key dynamical diagnostic is the projected spin─orbit angle—the alignment between the stellar spin and the planetary orbit—which provides crucial tests for theoretical models. This angle can be determined using the Rossiter─McLaughlin effect. Although measurements exist for over 200 planets, the overall distribution of these angles is not yet fully understood, motivating further observations across the full parameter space. We analyze archival HARPS and HARPS-N spectroscopic transit time series of nine gas giant exoplanets on short orbits and one brown dwarf. We derive their projected spin─orbit angle λ. We find aligned projected orbits for all nine gas giants as well as the brown dwarf. Furthermore, we are able to derive the true spin─orbit angle for the brown dwarf EPIC 219388192b,  ψ=22−13+10  deg. These projected prograde orbits are consistent with quiet disc migration disfavoring violent events exciting the orbits in the history of these systems. Finally, we investigate the current overlap between spin-orbit angle measurements and atmospheric characterization targets. While we find no strong observational biases due to the spin─orbit angle, we note that the majority of planets with atmospheric data still lack spin─orbit measurements. This incompleteness of the dynamical information may limit the interpretation of upcoming atmospheric surveys.

Keywords: Exoplanet dynamics, Exoplanet migration, Brown dwarfs, Hot Jupiters, Exoplanets, Radial velocity
The Polar Orbit of TOI-2374 b, a Planet in the Neptunian Ridge. The "Neptunian ridge" is a recently identified peak in the frequency of planets with sizes between that of Neptune and Saturn orbiting their host stars with periods between 3 and 6 days. These planets may have formed similarly to their larger, hot Jupiter counterparts in the "3 day pileup," through a dynamically excited migration pathway. The distribution of stellar obliquities in hot Neptune systems may therefore provide a vital clue as to their origin. We report a new stellar obliquity measurement for TOI-2374b, a planet in the Neptunian ridge (P = 4.31 days, Rp = 7.5 R⊕). We observed a spectroscopic transit of TOI-2374b with the Keck Planet Finder, detecting the Rossiter─McLaughlin (RM) anomaly with an amplitude of 3 m s−1, and measured a sky-projected obliquity of  λ=81°−22∘+23∘ , indicating an orbit significantly misaligned with the spin axis of its host star. A reloaded RM analysis of the cross-correlation functions confirms this misalignment, measuring  λ=65°−24∘+32∘ . Additionally, we measured a stellar rotation period of  Prot=26.4−0.8+0.9  days with photometry from the Tierras observatory, allowing us to deduce the three-dimensional stellar obliquity of  ψ=85.°9−9.°2+8.°6 . TOI-2374b joins a growing number of hot Neptunes on polar orbits. The high frequency of misaligned orbits for Neptunian ridge and desert planets, compared with their longer period counterparts, is reminiscent of patterns seen for the giant planets and may suggest a similar formation mechanism.

Keywords: Exoplanet astronomy, Exoplanet formation, Exoplanets
Detection of Helium Recombination Lines in the Cygnus X Diffuse Ionized Gas: Implications for Galactic Interstellar Medium Studies. We present the first detection of helium radio recombination lines (HeRRLs) at 800 MHz from the diffuse ionized gas (DIG) in the Cygnus X region, with an ionized helium-to-hydrogen ratio ( nHe+/nH+ ) of 0.06 ± 0.02, consistent with values observed in Galactic H II regions ionized by O6 stars or earlier. The data were obtained from a multifrequency RRL survey (342, 800, and 5800 MHz) using the Robert C. Byrd Green Bank Telescope, toward a region centered at  l=80.°0 ,  b=1.°4 , with an extent of  ±2.°85 . Several techniques were applied to mask out RRL emission from H II regions, and the remaining data were averaged to achieve the sensitivity required to detect HeRRLs from the DIG. Analysis of the pixel-to-pixel hydrogen line central velocities suggests that the 342 and 800 MHz line-forming regions are associated. Modeling of the averaged data indicates that the emission at these frequencies is dominated by an ionized component with an electron density of 2─15 cm−3 and an EM of 750─1600 pc cm−6 for an electron temperature of 8000 K. The derived properties of the DIG in Cygnus X are consistent with those reported for diffuse gas in the inner Galaxy. Previous attempts to detect HeRRLs in the inner Galaxy only yielded upper limits of 0.013, much lower than the value found in Cygnus X. Our detection has significant implications, including the potential for an additional hydrogen ionization source and changes in dust properties in the inner Galaxy.

Keywords: Interstellar line emission, Diffuse interstellar clouds
High Proper Motion Discoveries from the UKIRT Hemisphere Survey. We used the third data release of the UKIRT Hemisphere Survey to locate previously unrecognized high proper motion objects. We identify a total of 127 new discoveries with total proper motions ≳300 mas yr−1. A significant fraction of these sources with counterparts in the Gaia DR3 catalog are found to be distant (&gt;100 pc) low-mass stars, where their large tangential velocities and placement on color─magnitude diagrams suggest that they are likely low-metallicity M-type subdwarfs. Optical spectroscopy is used to confirm the low mass and low metallicity for two such sources. Using available optical and infrared photometry, we estimate the spectral type for all non-Gaia sources and find 10 likely late-M dwarfs, 15 objects with colors most consistent with L-type dwarfs, and nine possible T-type dwarfs. Follow-up spectroscopy is needed to confirm spectral types and further characterize these new discoveries.

Keywords: M subdwarf stars, Stellar astronomy, Brown dwarfs, Late-type stars
Dynamical Analysis of the HD 169142 Planet-forming Disk: Twelve Years of High-contrast Polarimetry. We present a dynamical analysis of the HD 169142 planet-forming disk based on high-contrast polarimetric imaging over a twelve-year observational period, offering insights into its disk evolution and planet─disk interactions. This study explores the evolution of scattered light features and their relationship with millimeter continuum emission. Archival visible-to-near-infrared scattered light observations from NACO, Spectro-Polarimetric High-Contrast Imager for Exoplanets Research, and Gemini Planet Imager combined with new observations from SCExAO reveal persistent nonaxisymmetric structures in both the inner and outer rings of the disk. Through Keplerian image transformations and phase cross correlation techniques, we show that the azimuthal brightness variations in the inner ring follow the local Keplerian velocity, suggesting these are intrinsic disk features rather than planet-induced spirals or shadows. The motion of the outer ring is weakly detected, requiring a longer observational baseline for further confirmation. Comparing scattered light features with ALMA 1.3 mm continuum data, we find that the scattered light traces the edges of dust structures in the inner ring, indicating complex interactions and a leaky dust trap around the water─ice snowline. These findings highlight the capability of long-term monitoring of circumstellar disks to distinguish planetary influences from Keplerian disk dynamics.

Keywords: Adaptive optics, Exoplanet astronomy, Direct imaging, Protoplanetary disks, Circumstellar disks, Polarimetry, Dynamical evolution
Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging. We present the discovery of GJ 251 c, a candidate super-Earth orbiting in the habitable zone (HZ) of its M dwarf host star. Using high-precision Habitable-zone Planet Finder and NEID RVs, in conjunction with archival RVs from the Keck I High Resolution Echelle Spectrometer, the Calar Alto High-resolution Search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrograph, and the Spectropolarimétre Infrarouge, we improve the measured parameters of the known planet, GJ 251 b (Pb = 14.2370 days;  msin(i)  = 3.85 −0.33+0.35  M⊕), and we significantly constrain the minimum mass of GJ 251 c, placing it in a plausibly terrestrial regime (Pc = 53.647 ± 0.044 days;  msinic  = 3.84 ± 0.75 M⊕). Using activity mitigation techniques that leverage chromatic information content, we perform a color-dependent analysis of the system and a detailed comparison of more than 50 models that describe the nature of the planets and stellar activity in the system. Due to GJ 251's proximity to Earth (5.5 pc), next generation, 30 meter class telescopes will likely be able to image terrestrial planets in GJ 251's HZ. In fact, GJ 251 c is currently the best candidate for terrestrial, HZ planet imaging in the northern sky.

Keywords: Bayesian statistics, Exoplanets, Bayes factor, Stellar activity, Bayes' Theorem, Direct imaging, Gaussian Processes regression, Radial velocity, Bayesian information criterion, Habitable zone, Habitable planets
LEO-Vetter: Fully Automated Flux- and Pixel-level Vetting of TESS Planet Candidates to Support Occurrence Rates. The Transiting Exoplanet Survey Satellite (TESS) has identified several thousand planet candidates orbiting a wide variety of stars, and has provided an exciting opportunity for demographic studies. However, current TESS planet searches require significant manual inspection efforts to identify planets among the enormous number of detected transit-like signatures, which limits the scope of such searches. Demographic studies also require a detailed understanding of the relationship between observed and true exoplanet populations, a task for which current TESS planet catalogs are rendered unsuitable by the subjectivity of vetting by eye. We present LEO-Vetter, a publicly available and fully automated exoplanet vetting system designed after the Kepler Robovetter, which is capable of efficiently producing catalogs of promising planet candidates and making statistically robust TESS demographic studies possible. LEO-Vetter implements flux- and pixel-level tests against noise/systematic false positives and astrophysical false positives. The vetter achieves high completeness (91%) and high reliability against noise/systematic false alarms (97%) based on its performance on simulated data. We demonstrate the usefulness of the vetter by searching ∼200,000 M dwarf light curves, and reducing ∼20,000 transit-like detections down to 172 uniformly vetted planet candidates. LEO-Vetter facilitates analyses that would otherwise be impractical to perform on all possible signals due to time constraints or computational limitations. Users will be able to efficiently produce their own TESS planet catalog starting with transit-like detections, as well as have the framework needed to characterize their catalog's completeness and reliability for occurrence rates.

Keywords: Astronomical object identification, Exoplanet catalogs, Exoplanet astronomy, Exoplanet detection methods, Transit photometry