Sazuna/UAT_keywords huggingface dataset:
The Chemical Diversity of Giant-planet Nurseries as Revealed by ALMA. With the giant exoplanet occurrence rate peaking around stars of 1.5─2.0 solar masses (M⊙), there is strong motivation to characterize the disks that set their formation conditions. Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) allow us to investigate both the availability of different molecules in disks and infer the radial distribution of elemental abundances, enabling us to make connections to exoplanet systems. Here we present a survey of six transition disks around young F-, A-, and B-type stars using ALMA. We find 13C18O, CS, SO, and H2CO in all six systems, as well as 10 additional molecules in a subset of disks, including detections of H2S, 33SO, and CH3OCH3. Using these data, and literature data where available, we construct the first comprehensive picture of Herbig disk chemistry. We find clear correlations between molecular tracers of C/O &gt; 1 environments (e.g., CS, C2H) and disk mass, as traced by C18O line flux. In contrast, tracers of C/O &lt; 1 environments (e.g., SO, CH3OH) do not show significant correlations with disk mass. Interestingly, these molecules are relatively brighter in lower-mass disks, with their presence primarily linked to disks with central cavities and spirals. Finally, we show that the observed chemical diversity seen across Herbig disks leads to varying C/O regimes at the orbital radii of candidate protoplanets identified within these disks. When comparing these inferred disk C/O ratios with those measured for directly imaged exoplanets, we find a notable overlap and show that low C/O gas is common on tens of au scales in Herbig disks.

Keywords: Exoplanet atmospheric composition , Radio astronomy, Protoplanetary disks, Astrochemistry
Initial Characterization of Stellar Photometry of Roman Images from the OpenUniverse Simulations. NASA's Nancy Grace Roman Space Telescope (Roman) will provide an opportunity to study dark energy with unprecedented precision and accuracy using several techniques, including measurements of high-z Type Ia Supernovae (SNe Ia; z ≲ 3.0) via the High-Latitude Time Domain Survey (HLTDS). In this work, we do an initial "benchmark" characterization of the photometric repeatability of stellar fluxes, which must be below 1% when sky noise is subdominant in order to enable a number of calibration requirements. Achieving this level of flux precision requires attention to Roman's highly structured, spatially varying, undersampled point-spread function (PSF). In this work, we build a library of effective PSFs (ePSFs) compatible with the OpenUniverse HLTDS simulations. Using our library of ePSFs, we recover stellar flux to between 0.6% and 1.2% photometric precision, finding that redder bands perform better by this metric. We also find that flux recovery is improved by up to 20% when a chip (sensor chip assembly, SCA) is divided into eight sub-SCAs in order to account for the spatial variation of the PSF. With our optimized algorithm, we measure nonlinearity due to photometry (magnitude dependence) of ∣sNL∣ &lt; 1.93 × 10−3 dex−1, which is still larger than stated requirements for detector effects and indicates that further work is necessary. We also measure the dependence of photometric residuals on stellar color and find the largest possible dependence in R062, implying a color-dependent PSF model may be needed. Finally, we characterize the detection efficiency function of each OpenUniverse Roman filter, which will inform future studies.

Keywords: Stellar photometry, Surveys, Observational cosmology, Astronomy data analysis, Astronomical techniques, Photometry
Two-source Terrestrial Planet Formation with a Sweeping Secular Resonance. The models that most successfully reproduce the orbital architecture of the solar system terrestrial planets start from a narrow annulus of material that grows into embryos and then planets. However, it is not clear how this ring model can be made consistent with the chemical structure of the inner solar system, which shows a reduced-to-oxidized gradient from Mercury to Mars and a parallel gradient in the asteroid belt. We propose that there were two primary reservoirs in the early inner solar system: a narrow, refractory-enriched ring inside of 1 au; and a less massive, extended planetesimal disk outside of 1 au, with oxidation states ranging from enstatite chondrites to ordinary chondrites. We show through a suite of N-body simulations that an inwardly sweeping secular resonance, caused by aerodynamic drag and perturbations from a mean-motion resonant Jupiter and Saturn, gathers the outer planetesimal disk into a narrow ring that migrates radially, forms Mars, and contributes oxidized material to proto-Earth. Remaining unaccreted planetesimals can be implanted into the asteroid belt as the parent bodies of aubrites and non-carbonaceous iron meteorites, while the most reduced material is not implanted and thus is unsampled in the meteorite collection. This model explains the oxidation and isotopic gradients within the inner solar system within the context of a low-viscosity, magnetic-wind-driven disk.

Keywords: Cosmochemistry, Solar system formation, Planetary-disk interactions, Solar system terrestrial planets
WISE/CatWISE Constraints on Dysonian Waste-heat Technosignatures in Nearby Galaxies. We search for galaxy-scale (Dysonian) waste heat in the mid-infrared using WISE. Starting from the 2MASS Redshift Survey, we crossmatch to CatWISE2020 and AllWISE, apply standard MIR AGN/starburst vetoes (Stern, Assef R90, Jarrett), and treat W1 and W2 as stellar baselines and W3 and W4 as constraining bands. For each galaxy and for blackbody waste heat temperatures T = 150─600 K, we convert W3/W4 photometry into conservative 3σ per-galaxy upper limits on the bolometric waste heat luminosity using the WISE bandpass color correction. The resulting distributions have median caps of ∼(5─9) × 108 L ⊙ across T = 150─600 K. Aggregated at the population level, the one-sided 95% upper bound on the fraction of nearby galaxies that could host waste heat above a given threshold monotonically decreases with threshold and asymptotes to ≃1/6500 at high thresholds (set by the sample size). Sensitivity transitions from W4 at T ≲ 200 K to W3 at T ≳ 300 K. Interpreted with the AGENT formalism, a fiducial Milky Way like stellar luminosity L ⋆ = 3 × 1010 L ⊙implies typical per galaxy caps of α ≡ L wh/L ⋆ ≲ 1.7%─2.9% over T = 150─600 K (e.g., α ≲ 1.8% at T = 300 K). At T ≃ 300 K, no more than f 95 ≃ 1.61 × 10−4 ( ≃0.0161%) of nearby galaxies can host KIII-scale systems reprocessing ≳21% of a Milky-Way-like stellar luminosity into ∼300 K waste heat.

Keywords: Extragalactic astronomy, Search for extraterrestrial intelligence, Technosignatures, Astrobiology
CLIP-GMC: Contrastive Language-image Pretraining Model for Few-shot Galaxy Morphology Classification. Galaxy morphology classification relies on precise structural feature characterization, yet expert classifications are scarce. While citizen science initiatives (e.g., Galaxy Zoo) provide millions of crowd-sourced labels, traditional supervised models lack cross-dataset generalizability and few-shot adaptability. To address these, we propose Contrastive Language-image Pretraining Model for Galaxy Morphology Classification (CLIP-GMC), a framework leveraging the contrastive vision-text model CLIP to unlock the utility of citizen science labels for robust classification. CLIP's pretrained embedding space enables flexible, text-guided feature learning with superior transfer and zero-shot capabilities. CLIP-GMC involves two stages: (1) pretraining the model using synthetic image-text pairs generated from Sloan Digital Sky Survey data in Galaxy Zoo 2, translating hierarchical morphological decisions into descriptive text; (2) validating the model on Galaxy MNIST (4 class) and Galaxy10 the DECam Legacy Survey (DECaLS; 10 class) across varying training data ratios (100%─1%) to assess few-shot and cross-dataset transferability. Experimental results show its exceptional superiority in low-data regimes and competitive high-data performance. On Galaxy10 DECaLS, it achieves 0.8390 accuracy/0.8350 macro-F1 with 50% data (comparable to full-data ConvNeXt-B: 0.8431/0.8250) and 0.7203/0.6991 with 1% data, outperforming supervised baselines and Zoobot2. At 100% data, its 0.8431 accuracy matches ConvNeXt-B but is slightly lower than Zoobot2 (GZ-Evo: 0.8670). On Galaxy MNIST, 10% data yields 0.9234 accuracy (surpassing full-data supervised 0.9052) and reliable zero-shot transfer (0.6865/0.6474), with 100% data accuracy (0.9321) comparable to Zoobot2. These highlight CLIP-GMC's exceptional data efficiency and generalizability, offering a robust solution for data-scarce galaxy morphology classification.

Keywords: Neural networks, Convolutional neural networks, Astronomy data analysis, Galaxy classification systems, Astronomical methods
Analytical Solutions for Planet-scattering Small Bodies. Gravitational scattering of small bodies (planetesimals) by a planet remains a fundamental problem in celestial mechanics. It is traditionally modeled within the circular restricted three-body problem, where individual particle trajectories are obtained via numerical integrations. Here, we use Öpik's close-encounter framework to study the random walk of the orbital energy x for an ensemble of test particles on planet-crossing orbits. We show that the evolution of each particle's orbital elements (a, e, i) is fully encapsulated by the 3D rotation of the relative velocity vector U∞, whose magnitude remains constant. Consequently, the system can be reduced to two degrees of freedom. By averaging over all possible flyby geometries, we derive explicit expressions for the drift and diffusion coefficients of x. We then solve the resulting Fokker─Planck equation to obtain a closed-form solution for the time evolution of the particle distribution. A characteristic scattering timescale naturally emerges, scaling as  (Pp/Mp2)/500 , where Pp is the planet's orbital period and Mp its mass ratio to the central star. The typical ejection speed of small bodies by a planet is estimated to be  3vpMp1/3 , where vp is the planet's orbital speed. Our analytical solution constitutes a universal law applicable to both the solar system and exoplanetary systems, providing a computationally efficient alternative to costly N-body simulations for studying the orbital distributions and ejection of planetesimals and planets (e.g., Kuiper Belt, Oort Cloud, debris disks, interstellar objects, and free-floating planets).

Keywords: Celestial mechanics, Free floating planets, Planetary dynamics, Interstellar objects
A MaNGA about the Legacy. I. Connecting the Assembly of Stellar Halo with the Average Star Formation History in Low-redshift Massive Galaxies. We investigate the connection between stellar mass distribution, assembly history, and star formation timescales in low-redshift massive early-type galaxies (ETGs) by combining deep LegacySurvey imaging with MaNGA's spatially resolved spectroscopy. Focusing on stellar population properties, especially the [Mg/Fe] abundance ratio, we analyze stacked spectra using both absorption line indices and full-spectrum fitting. We find that, among massive ETGs with identical average stellar mass distributions beyond 20 kpc, those with higher central velocity dispersion (σ⋆,cen) are older and more α-enhanced, suggesting a connection between the in situ star formation in the past and the central gravitational potential today for massive ETGs with a similar stellar accretion history. Conversely, at fixed σ⋆,cen and total stellar mass, galaxies with more extended stellar halos show lower [Fe/H], higher [Mg/Fe], and older ages, indicating an intriguing link between early starburst and quenching and later ex situ assembly. These results demonstrate that the evolution of massive galaxies cannot be fully described by simple scaling relations alone, as the interplay between in situ star formation and ex situ accretion leaves distinct imprints in both their inner and outer stellar populations. Our findings highlight the importance of extending stellar population studies to large radii and underscore the scientific potential of next-generation integral-field-unit surveys and deep, high-resolution spectroscopy for probing the galaxy─halo connection.

Keywords: Galaxy stellar halos, Galaxy formation, Galaxy physics, Galaxy structure
TOI-4495: A Pair of Aligned, Near-resonant Sub-Neptunes That Likely Experienced Overstable Migration. We report the discovery of a sub-Neptune and a Neptune-like planet (R b=2.48−0.10+0.14  R⊕, R c=4.03−0.15+0.23  R⊕) orbiting the F-type star TOI-4495. The planets have orbital periods of 2.567 and 5.185 days, lying close to a 2:1 mean-motion resonance (MMR). Our photodynamical analysis of the TESS light curves constrains the planetary masses to Mb = 7.7 ± 1.4 M⊕and Mc = 23.2 ± 4.7 M⊕. The measured masses and radii indicate the presence of volatile-rich gaseous envelopes on both planets. The Rossiter─McLaughlin effect and the Doppler shadow of TOI-4495 c reveal a well-aligned orbit with a projected stellar obliquity of  λ=−2.3−7.8+8.3° . Combined with the low mutual inclination constrained by the photodynamical analysis (∆I &lt; 8.7°), the planetary orbits are likely coplanar and aligned with the host star's spin axis. We show that the planets are near, but not in, the 2:1 MMR, with a circulating resonant angle. We also find substantial free eccentricity for the inner planet, TOI-4495 b ( eb=0.078−0.013+0.02 ). Given the observed proximity to the 2:1 resonance and the more massive outer planet, TOI-4495 b and c are particularly susceptible to resonant overstability, which in turn can explain the observed eccentricity by converting resonantly excited eccentricity into free eccentricity. However, additional mechanisms (e.g., planetesimal scattering) may be required to further excite the eccentricity by ∼4%. To prevent tidal damping from reducing the eccentricity below the observed level over the star's lifetime (1.9 Gyr), the reduced tidal quality factor of TOI-4495 b must be  Q'≳105 , consistent with the presence of a thick envelope on the planet.

Keywords: Exoplanet astronomy, Transit timing variation method, Orbital resonances
Quantifying the Contamination of TESS Ecliptic-plane Light Curves by Minor Planets. Though missions devoted to time series photometry focus primarily on targets far beyond the solar system, their observations can be contaminated by foreground minor planets, especially near the ecliptic plane, where solar system objects are most prevalent. Crucially, depending on one's choice of data reduction/background estimation algorithm, these objects can induce both apparent brightening and/or dimming events in processed light curves. To quantify the impact of these objects on archived TESS light curves, we used N-body integrations of all currently known minor planets to postdict all 600,000+ of their interactions with stars selected for high-cadence observations during TESS ecliptic plane sectors. We then created mock images of these moving sources and performed simple aperture photometry using the same target and background apertures used in SPOC processing. Our resulting 10,000+ target-specific light curves, which faithfully model the time-dependent positions and magnitudes of the actual solar system objects that approached each target, reveal that &gt;95% of high-cadence ecliptic plane targets experience a minor planet crossing within 1 TESS pixel of the source. Additionally, 50% of all T &gt; 13 mag targets experience at least one instantaneous moment where the contaminating flux from minor planets exceeds 1% of the target flux. We discuss these population-level results and others, and highlight several case studies of bright flybys.

Keywords: Transit photometry, Asteroids, Time series analysis
The Milky Way Bulge Extratidal Star Survey: NGC 6569. We present spectroscopic evidence for tidal debris associated with the bulge globular cluster NGC 6569, based on medium-resolution (R ∼ 11,000) spectra of 303 stars obtained with the Anglo-Australian Telescope. Targets were selected using Blanco DECam Bulge Survey photometry with Gaia DR3 astrometry, and span  ∼7' ─ 30' (i.e., 1─5 rt, where rt is the King-model tidal radius) from the cluster center. Theoretical modeling shows that the Jacobi radii can vary between  8' ─ 11' and  18' ─ 22'  over the orbit, likely leaving stars around the cluster that are transitioning into the predicted leading and lagging tidal tails. We identify 40 stars in this sample that exhibit chemical and kinematic properties consistent with previous, or borderline, cluster membership. The seven best candidates have S/N &gt; 30, with [Fe/H] = ─0.83 ± 0.14 dex and [α/Fe] = +0.38 ± 0.06 dex, consistent with NGC 6569's bound population. Our findings provide evidence that NGC 6569 is actively losing stars through tidal stripping, contributing to the bulge field population at a present rate of 1.0─1.6 M⊙ Myr−1, which corresponds to ≍5.6% ± 1.3% of its present-day mass per Gyr. This work is part of the Milky Way Bulge Extra-Tidal Star Survey and represents our first detailed study of a massive bulge globular cluster in this context.

Keywords: Globular star clusters, Tidal disruption, Galaxy bulges
Investigations of Ultraviolet Spectral Approximations for Computing Photodissociation and Photoionization Reaction Rates. The chemical composition of protoplanetary disks, especially in the molecular layer and above, is set by photoprocesses driven by stellar radiation fields. Chemical modeling approaches in the literature treat the radiation field with varying levels of sophistication with respect to the propagation of photons or the wavelength dependence of photoprocesses. We present a systematic investigation of how simplifications to the radiation field treatment impact our inferences of disk composition. Using a modified version of the NAUTILUS code applicable for the highly irradiated environment of disks, we evaluate the accuracy of six different methods of approximating the ultraviolet stellar spectra, and therefore the computed reaction rates, for six young star and disk models (using spectral energy distributions of the stars RECX 15, GM Aur, RU Lup, HD 135344B, MWC 480, and AB Aur). We compare the rates computed via each approximation, and we investigate differences in their modeled chemistry. We find that the approximations can lead to significant differences in the rates for photoprocesses like desorption, dissociation, and ionization. Of the approximations considered, low-resolution ultraviolet spectra provide rates consistent to within a factor of 2 from the fiducial high-resolution ultraviolet spectra. Otherwise, accuracy of the other approximations is highly dependent on the host star and molecule. More reliable predictions are then best achieved by either using a downsampled ultraviolet spectrum from the source in question, or a reasonable ultraviolet spectral template. Otherwise, we advise that underlying assumptions on the ultraviolet spectrum are carefully considered when modeling disk chemistry across the pre-main-sequence stellar distribution.

Keywords: Interstellar molecules, Astronomical models, Astrochemistry, Protoplanetary disks, Chemical reaction network models
Aligned, Misaligned, and Polar Orbits of Hot Jupiters: Measuring Spin-orbit Angles via Doppler Tomography with HARPS-N. Although the migration of hot Jupiters is not yet fully understood, measurements of the projected spin─orbit angle λ help shed light on the processes involved. Here we present Doppler tomography of three known hot Jupiters to determine their λ orientation: HAT-P-49 b, HAT-P-57 A b, and XO-3 A b. Our analysis explores the impact of cross-correlation processing methods on the detectability and characterization of the planet's Doppler shadow using up to three independent routines for cross-correlation functions extraction; those being: Yabi, iSpec, and IRAF. After accounting for differences among the results obtained with the various routines, we report: first, the HAT-P-49 system is a case of a hot Jupiter on a polar orbit with λ = ─85 .° 3 ± 1 .° 7, second, HAT-P-57 A indicates practically no deviation of the planet's projected orbit from the host's equatorial plane with  λ=─0.4−1.9+1.4° , and third, the XO-3 A system with the measured value of  λ=38−4+3°  lies in between an aligned and a perpendicular orientation, which is a less populated region of the spin─orbit distribution. Our findings highlight both the diversity of spin─orbit angles among close-in giant planets and the potential discrepancies in their measurement that can arise from different approaches to constructing the cross-correlation functions.

Keywords: Exoplanet migration, Planetary system evolution, Hot Jupiters, Exoplanets
Linear Image Regridding and Coaddition with Oversampled Point Spread Functions: Lessons from 1D. Image regridding and coaddition have a wide range of applications in astronomical observations. Image Combination (IMCOM), an algorithm that provides control over point-spread function (PSF) and noise in coadded images, has been found to meet the stringent requirements of weak gravitational lensing cosmology with the forthcoming Nancy Grace Roman Space Telescope. In this work, I introduce a new algorithm, Fast IMCOM, which outperforms traditional IMCOM in terms of both efficiency and quality. After explaining the underlying philosophy and mathematical formalism, I conduct systematic comparisons between IMCOM and Fast IMCOM in terms of PSF reconstruction in 1D. While a 2D implementation is beyond the scope of this paper, I demonstrate how to generalize Fast IMCOM to 2D and discuss practical issues involved. This new algorithm has the potential of reducing both the computational costs and storage requirements (current estimates are ∼100 M core-hours and ∼1.5 PB, respectively) of the Roman High Latitude Imaging Survey (HLIS) by an order of magnitude. Meanwhile, it provides implications for the dithering patterns of Roman surveys (extrapolated from 1D to 2D). I also address potential applications of Fast IMCOM beyond the Roman HLIS, with focus on other weak lensing programs and Roman time domain surveys; the actual range of use cases is likely beyond what is discussed here.

Keywords: Weak gravitational lensing, Astronomy image processing
Two Potential Exoplanets around A-type Stars Selected from 18 Planetary Candidates. We screen and analyze exoplanet candidates around A-type stars (defined as Teff between 7500 and 10,000 K) observed by the Transiting Exoplanet Survey Satellite to evaluate their likelihood of being genuine exoplanets. Our analysis involves transit signal searches, light-curve detrending, estimation of nearby-source contamination, and calculation of false-positive probabilities (FPPs). Among the 18 candidates analyzed, four exhibit relatively low FPP values (&lt;15%). Two candidates are excluded from further analysis due to the lack of stellar parameter data. Six candidates show no clearly detectable transit signals, likely due to shallow or weak features, while six candidates exhibit relatively high FPP values, leaving their authenticity uncertain. Among the four low-FPP targets, two—TIC 48031665 and TIC 259230140—stand out as the most promising. TIC 48031665 shows a very shallow transit signal but has a very low FPP and minimal nearby starlight contamination. TIC 259230140 displays a clear U-shaped transit light curve typical of planetary transits, along with slightly higher yet still low FPP and contamination levels. These two objects are therefore considered the most promising candidates identified in this study.

Keywords: Transits, A stars, Exoplanets, Light curves, Exoplanet astronomy, Transit photometry