Sazuna/UAT_keywords huggingface dataset:
The OATMEAL Survey. II. The 3D Spin─Orbit Obliquity of an Eccentric Transiting Brown Dwarf in the Ruprecht 147 Open Cluster. We present a new analysis of the CWW 89 system as part of the Orbital Architectures of Transiting Massive Exoplanets And Low-mass stars (OATMEAL) survey. The CWW 89 system is a member of the 2.8 Gyr old Ruprecht 147 (NGC 6774) cluster and consists of two stars, CWW 89A (EPIC 219388192) and CWW 89B, with the primary hosting a transiting brown dwarf, CWW 89Ab. We use in-transit, highly precise radial velocity measurements with the Keck Planet Finder to characterize the Rossiter─McLaughlin (RM) effect and measure the projected spin─orbit obliquity ∣λ∣ = 1 .° 4 ± 2 .° 5 and the full 3D spin─orbit obliquity of the brown dwarf to be  ψ=15.1−10.9+15.0∘ . This value of λ implies that the brown dwarf's orbit is prograde and well-aligned with the equator of the host star, continuing the trend of transiting brown dwarfs showing a preference for spin─orbit alignment (λ ≍ 0°) regardless of the stellar effective temperature. This contrast with the transiting giant planet population, whose spin─orbit alignments depend on host Teff, shows an increasingly clear distinction in the formation and orbital migration mechanisms between transiting giant planets and transiting brown dwarfs like CWW 89Ab. For this system in particular, we find it plausible that the brown dwarf may have undergone coplanar high-eccentricity migration influenced by CWW 89B.

Keywords: Exoplanet dynamics, Star-planet interactions, Exoplanet migration, Brown dwarfs
Cosmic-ray Detection and Rejection for CSST. As a space telescope, the Chinese Space Station Survey Telescope (CSST) will face significant challenges from cosmic-ray (CR) contamination. These CRs will severely degrade image quality and further influence scientific analysis. Due to the CSST's sky survey strategy, traditional multi-frame stacking methods become invalid. The limited revisits prompted us to develop an effective single-image CR processing method for CSST. We retrained the DeepCR model based on CSST simulated images and achieved 97.90% ± 0.18% recall and 98.67% ± 0.05% precision on CR detection. Moreover, this paper puts forward an innovative morphology-sensitive inpainting method, which focuses more on areas with higher scientific value. We trained a UNet++ model especially on contaminated stellar/galactic areas, alongside adaptive median filtering for background regions. This method achieves effective for CRs with different intensities and different distances from centers of scientific targets. By this approach, the photometric errors of CR-corrected targets could be restricted to the level comparable to those of uncontaminated sources. Also, it increases the detection rate by 13.6% compared to CR masking. This method will provide a robust CR mitigation for next-generation space telescopes.

Keywords: Space telescopes, Convolutional neural networks, Astronomy image processing, Cosmic rays
The Effect of Guide Star Variability on PLATO Pointing Stability. The main science goal of the PLAnetary Transits and Oscillations of stars (PLATO) is to detect and characterize extrasolar planets, including terrestrial planets in the habitable zone (HZ) of their host stars. Detecting rocky planets in the HZ requires high photometric stability, which depends on the spacecraft's pointing performance. PLATO's pointing performance is managed by the Fine Guidance System (FGS), which utilizes a catalog of guide stars to determine the spacecraft's attitude. The FGS compares the position of these guide stars within the telescope's CCDs to their position in the sky to determine the spacecraft's orientation. This is critical as PLATO's science mission requires an extremely high level of pointing accuracy. High astrophysical variability in these guide stars can cause apparent shifts in their centroids in the presence of background stellar contaminants. If this happens during science operations, the apparent movement in the guide stars' centroids will cause the spacecraft to move in an attempt to maintain pointing direction. This movement creates systematic bias in any photometric measurements taken by the spacecraft. The goal of this project is to quantify what, if any, effect astrophysical variability in guide stars will have on PLATO's pointing stability. By correlating the impact on performance with variability indicators (like Flicker in the Power Domain), we find that the PLATO FGS is robust against stellar variability.

Keywords: Exoplanet astronomy, Astronomical instrumentation, Variable stars
iSTARMOD: A Python Code to Quantify Chromospheric Activity by Using the Spectral Subtraction Technique. The use of the spectral subtraction technique allows measurements of chromospheric activity in late-type stars across several activity indicators, such as Hα and the other Balmer lines in the visible, He I D3 and Na I D1, D2, Ca II H and K, and Ca II infrared triplet, as well as the Paschen series and He I λ10830 lines in the near-infrared. iSTARMOD is an updated and extended version of the original STARMOD code and its subsequent modifications. iSTARMOD is presented in this paper as a Python code developed to quantify chromospheric activity by using the spectral subtraction technique. iSTARMOD improves usability, modularity, and integration with modern data analysis workflows and is publicly available, including several examples that help one learn how to use and test the code. The iSTARMOD code is accompanied here with a series of calibrations of χ-functions, to transform the excess emission equivalent widths measured through iSTARMOD into absolute surface fluxes. The method provided with this code and the corresponding flux calibrations allows for the automatic characterization of the chromospheric activity of a large number of spectra or a large number of stars and is also very useful for mitigating the effect of activity on radial velocities in the search for exoplanets.

Keywords: Late-type stars, Astronomy software, Stellar activity, Stellar astronomy, Stellar spectral lines
Galactic Chemical Evolution of Short-lived Radioactive Isotopes Produced by Explosive Nucleosynthesis: <SUP>60</SUP>Fe and <SUP>53</SUP>Mn. Several short-lived radionuclides (SLRs) are know to have existed in the early solar system (ESS). These species, which typically decay with half-lives of the order of a few million years, can be used to probe the timescales of events preceding the birth of the Sun. We investigate the ESS origin of 53Mn, produced by core-collapse supernovae (CCSNe) and Type Ia supernovae (SNe Ia), and 60Fe, produced exclusively by CCSNe. We model the evolution of the radioactive-to-stable abundance ratios of these SLRs with a Galactic chemical evolution (GCE) framework accounting for different SN yields, SN Ia delay times, and other Galactic features (K). A further set of models is calculated assuming that SNe Ia did not contribute any 53Mn to the ESS. The predicted ratios are compared to meteoritic ratios to derive a distribution of solar isolation times that includes uncertainties due to stochastic chemical enrichment and measurements of the ESS values. The isolation times are then compared to those of 107Pd and 182Hf calculated in previous work. A self-consistent solution can be found within the current uncertainties, especially when using the GCE setups with K = 1.6 and 2.3, although the maximum likelihood for the 60Fe distribution is typically ∼4─5 Myr shorter than for 53Mn. The predicted 60Fe/53Mn ratio, instead, is completely inconsistent with the ESS value; this could be resolved using a larger fraction of faint CCSNe than usually considered in GCE models.

Keywords: Solar system formation, Solar nebulae, Core-collapse supernovae, Abundance ratios, Galaxy chemical evolution, Interstellar abundances, Solar system, Chemical enrichment, Type Ia supernovae
The MDW Hα Sky Survey: Data Release 1. The Mittelman─di Cicco─Walker (MDW) Hα Sky Survey is an autonomously operated all-sky narrowband (3 nm) Hα imaging survey. The survey was founded by amateur astronomers, and the northern sky (decl. ≥ 0°) is presented here in its second stage of refinement for academic use. Each 3.6 deg2 MDW field has 12 20 minutes individual exposures with a pixel scale of 3 .″ 2, a typical point-spread function of 6″, and a stack point-source depth of 16─17 mag. The northern MDW Survey Data Release 1 (DR1) includes calibrated mean and individual images, star-removed mean fields, and point-source catalogs for all images matched to Data Release 1 of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) and the INT Galactic Plane Survey. (All DR1 components are available at https://mdw.astro.columbia.edu. The catalogs are also made available in the AAS Journals Zenodo repository: doi:10.5281/zenodo.17307324.) Our initial study of Hα filament widths finds a typical FWHM of 30″─45″ in the Lyra region. The matched catalogs (with a median match distance of ∼0 .″ 5), combined with our distinctive narrowband photometry, are also used to identify Hα variable and excess sources. These initial studies highlight some of the many scientific uses of the MDW Hα survey.

Keywords: Amateur astronomy, Sky surveys, H II regions, Astronomy data reduction
On the Exoplanet Yield of Gaia Astrometry. We reexamine the expected yield of Gaia astrometric planet detections using updated models for giant-planet occurrence, the local stellar population, and Gaia's demonstrated astrometric precision. Our analysis combines a semianalytic model that clarifies key scaling relations with more realistic Monte Carlo simulations. We predict 7500 ± 2100 planet discoveries in the 5 yr dataset (Data Release 4 (DR4)) and 120,000 ± 22,000 over the full 10 yr mission (Data Release 5 (DR5)), with the dominant error arising from uncertainties in giant-planet occurrence. We evaluate the sensitivity of these forecasts to the detection threshold and the desired precision for measurements of planet masses and orbital parameters. Roughly 1900 ± 540 planets in DR4 and 38,000 ± 7300 planets in DR5 should have masses and orbital periods determined to better than 20%. Most detections will be super-Jupiters (3─13 MJ) on 2─5 au orbits around GKM-type stars (0.4─1.3 M⊙) within 500 pc. Unresolved binary stars will lead to spurious planet detections, but we estimate that genuine planets will outnumber them by a factor of 5 or more. An exception is planets around M dwarfs with a &lt; 1 au, for which the false-positive rate is expected to be about 50%. To support community preparation for upcoming data releases, we provide mock catalogs of Gaia exoplanets and planet-impostor binaries.1 1 https://github.com/CalebLammers/GaiaForecasts https://github.com/CalebLammers/GaiaForecasts

Keywords: Gaia, Extrasolar gaseous giant planets, Astrometry, Exoplanets
Exploring Warm Jupiter Migration Pathways with Eccentricities. II. Correlations with Host Star Properties and Orbital Separation. Warm Jupiters with orbital periods of ≍10─365 days represent a population of giant planets located well within the water ice line but beyond the region of tidal influence of their host star relevant for high-eccentricity tidal migration. Orbital eccentricities offer important clues about the formation and dynamical history of warm Jupiters because in situ formation and disk migration should imprint near-circular orbits whereas planet scattering should excite eccentricities. Based on uniform Keplerian fits of 18,587 radial velocities (RVs) targeting 200 warm Jupiters, we use hierarchical Bayesian modeling to evaluate the impact of host star metallicity, stellar mass, and orbital separation on the reconstructed population-level eccentricity distributions. Warm Jupiters take on a broad range of eccentricities, and their population-level eccentricities are well modeled using a Beta distribution with α = 1.00 −0.08+0.09  and β = 2.79 −0.26+0.28 . We find that 27 −4+3%  of warm Jupiters have eccentricities consistent with near-circular orbits (e &lt; 0.1), suggesting that most warm Jupiters (73 −3+3% ) detected are dynamically hot. Warm Jupiters orbiting metal-rich stars are more eccentric than those orbiting metal-poor stars—in agreement with earlier findings—but no differences are observed as a function of stellar host mass or orbital separation, at least within the characteristic ranges probed by our sample (≍0.5─2.0 M⊙ and 0.1─1 au, respectively). In this sense, metallicity plays a larger role in shaping the underlying eccentricity distribution of warm Jupiters than stellar mass or final orbital distance. These results are broadly consistent with planet scattering playing a major role in shaping the orbital architectures of close-in giant planets.

Keywords: Exoplanet migration
TESS Investigation—Demographics of Young Exoplanets (TI-DYE). IV. A Jovian-radius Planet Orbiting a 34 Myr Sun-like Star in the Vela Association. The discovery of infant (&lt;50 Myr), close-in (&lt;30-day-period) planets is vital in understanding the formation mechanisms that lead to the distribution of mature transiting planets as discovered by Kepler. Despite several discoveries in this age bin, the sample is still too small for a robust statistical comparison to older planets. Here we report the validation of TOI-6448b, an 8.8 ± 0.8 R⊕ planet on a 14.8-day orbit. TOI-6448 was previously identified to be a likely member of Vela Population IV. We confirm the star's membership and rederive the age of the cluster using isochrones, variability, and gyrochronology. We find the star, and thus planet, to be 34 ± 3 Myr. Like other young planets, TOI-6448 b lands in a region of parameter space with few older planets. While just one data point, this fits with prior findings of an excess of 5─11 R⊕ planets around young stars far beyond what can be explained by reduced sensitivity at young ages. Our ongoing searches of Vela, Taurus-Auriga, Sco-Cen, and Orion are expected to reveal dozens more &lt;50 Myr transiting planets.

Keywords: Transits, Exoplanets, Young star clusters, Young stellar objects, Transit photometry
A High-resolution Spectroscopic Survey of Directly Imaged Companion Hosts. II. Diversity in C/O Ratios among Host Stars. The era of JWST has enabled measurements of abundances of elements such as C, O, and even Na, S, K, and Fe in planetary atmospheres to very high precisions (∼0.1 dex). Accurate inference of planet formation using these elemental abundances requires the corresponding abundance measurements for the host star. We present the second set of results from our high-resolution spectroscopic survey of directly imaged companion host stars, measuring abundances of 16 elements (including C, O, Na, Mg, Si, S, K, and Fe) for five directly imaged companion host stars. Using both the spectral fitting and the equivalent width methods, we find solar C/O ratios for HR 2562 (0.58 ± 0.09), AB Pic (0.50 ± 0.14), and YSES 1 (0.45 ± 0.05), and subsolar C/O ratios for PZ Tel (0.28 ± 0.05) and β Pic (0.22 ± 0.06). The 4σ subsolar C/O detections for PZ Tel and β Pic highlight the importance of accurate stellar C/O estimates for constraining planet formation. Subsequently, we combine our abundances with those from our previous work to measure population-level average elemental abundances. We find supersolar carbon and oxygen for this stellar population, indicating that the protoplanetary disks around these stars were potentially rich in volatiles. We compare stellar C/O to those of their companions, revealing superstellar C/O for several objects that suggest planet-like formation mechanisms. We also compare the C/O of our directly imaged companion host star population with other planet host stars using the Kolmogorov─Smirnov Test, which indicates insufficient evidence to differentiate between the various stellar populations.

Keywords: High resolution spectroscopy, Stellar populations, Stellar abundances, Direct imaging, Atmospheric composition, Exoplanet formation
Simulated Impact on LSST Data of Starlink V1.5 and V2 Satellites. The new Starlink V2 satellites incorporate improvements to the chassis brightness through dielectric mirrors, off-pointing solar arrays, and blackened exposed components. For the general case in which the reflectivities are initially unknown, we simulate Legacy Survey of Space and Time (LSST) operations and repeated photometry of every satellite in simulated model constellations. We derive a brightness model of the Starlink V2 satellite and study the simulated apparent brightness as a function of the satellite position relative to the observer and the Sun. Simulated V2 Starlink satellites appear brightest at two distinct positions in the sky: toward the Sun at low elevations where light is specularly reflected, and nearly overhead where the satellite is closest to the observer. A simulation of Starlink V2 satellites at 550 km height distributed across a series of Walker constellations with varying inclinations was analyzed to study the impact on LSST observations. For every thousand V2 Starlink satellites observed, we find only 0.93 will appear brighter than 7th magnitude. The off-pointed solar array and reduced diffuse reflection of the chassis mitigate the brightness. Finally, we simulate lowering this Walker constellation to 350 km. Only 0.56 V2 Starlink satellites per thousand brighter than 7 AB magnitude will be observed in the first hour at this height. This is a 40% reduction in number of bright satellites entering the focal plane compared to the constellation at 550 km height. We find that a combination of factors yield an apparent surface brightness of these satellites for LSST operations only 5% brighter than at 550 km orbit.

Keywords: Night sky brightness, Optical astronomy, Astronomy data analysis, Artificial satellites, Astronomical techniques, Photometry
The Gaia─Kepler─TESS-host Stellar Properties Catalog: Uniform Physical Parameters for 10022 Host Stars and 10189 Planets. We present the first homogeneous catalog of Kepler, K2, and TESS host stars and the corresponding catalog of exoplanet properties, which contain 10022 stars and 10189 planets, respectively. We used isochrone fitting and Gaia DR3 photometry, parallaxes, and spectroscopic metallicities to compute precise, homogeneous Teff,  logg , masses, radii, mean stellar densities, luminosities, ages, distances, and V-band extinctions for 3387, 618, 6017 Kepler, K2, and TESS host stars, respectively. We compared our stellar properties to studies using fundamental and precise constraints, such as interferometry and asteroseismology, and find residual scatters of 2.8%, 5.6%, 5.0%, and 31%, with offsets of 0.2%, 1.0%, 1.2%, and 0.7% between our Teff, radii, masses, and ages and those in the literature, respectively. In addition, we compute planet radii, semimajor axes, and incident fluxes for as many as 4285, 678, and 5226 Kepler, K2, and TESS planets, respectively, and find that the exoplanet radius gap is less prominent in the K2, TESS, and combined samples than in the Kepler sample alone. We suspect this difference is due to heterogeneous planet-to-star radius ratios, shorter time baselines of K2 and TESS, smaller sample sizes, and the different gap locations hinted at by the K2 (∼1.5 R⊕) and TESS (∼1.8 R⊕) planet radius distributions. Finally, we identify a clear radius inflation trend in thousands of hot Jupiters and find 151 hot sub-Neptunian desert planets, in addition to a population of 233 young (≲1 Gyr) host stars as potential opportunities for testing theories of planet formation and evolution.

Keywords: Exoplanet catalogs, Stellar properties, Exoplanets, Exoplanet systems, Stellar classification, Planet hosting stars, Habitable zone
Discovery of 178 Open Clusters with Gaia DR3. We present 178 new open cluster candidates identified through the application of the HDBSCAN clustering algorithm to astrometric data from the Gaia DR3 catalog. The analysis was performed over 5770 1 deg2 fields centered on OB stars, which serve as tracers of Galactic spiral arms. Using the membership probabilities provided by HDBSCAN, we derived the mean proper motions, parallaxes, and fundamental parameters for each cluster. For a subset of 84 clusters, mean radial velocities were also determined using Gaia data. The cluster parameters (distances, ages, extinctions, and metallicities) were estimated through our nonsubjective multidimensional global optimization code, which fits theoretical isochrones to Gaia photometric data. The quality of the results and their uncertainty support the reality of the clusters, which span distances from 739 to 12,000 pc. Age estimates indicate that 59 clusters are younger than 50 Myr, 20 have intermediate ages, and 99 are classified as old clusters. These results highlight that there is still work to be done on open cluster discovery and reinforce the importance of regular updates to open cluster catalogs.

Keywords: Open star clusters
X-Ray and UV Observations of the Young Sun HIP 67522: Evidence of Lyα Absorption within the Planetary System. We present ultraviolet (UV) spectroscopy of the 17 Myr, G0V star HIP 67522. The UV spectrum is characterized by strong chromospheric and transition region emission lines. There was moderate spectral variability during the observations consisting of 15% stochastic fluctuation and two small flares releasing EUV ≃ 2─4 × 1032 erg in each event. We compare the broadband spectral energy distribution (SED; 4.7 Å─13.0 μm) of the star first presented in P. C. Thao et al. to the solar SED and show that the X-ray and UV (XUV) flux density at 1 au is 102─105 stronger (from 1000 Å down to 5 Å) in the young star compared to the present-day Sun. Attempts to reconstruct the intrinsic Lyα emission of the star failed to return physically realistic results. The discrepancy appears to arise from a population of neutral hydrogen within the system itself, extending to &gt;±500 km s−1. The absorption could be due to outflow from exoplanet atmospheric loss or from a stellar component; such a picture would require high spectral resolution observations and/or UV transit spectroscopy to confirm. Finally, we examine the evolution of the XUV emission from solar-type stars from ages of 17 Myr─9.4 Gyr and derive a scaling relation between far-UV Lyα and extreme-UV (EUV) emission as a function of stellar age. X-ray (1─100 Å) and EUV (100─911 Å) contributions to high-energy emission are 329 and 672 erg cm−2 s−1 at 1 au, respectively, suggesting that both may contribute to exoplanet heating at this epoch. The XUV emission levels at 17 Myr combined with the low density of the planet HIP 67522 b are consistent with models that predict that solar-type stars born with high rotation and activity levels will drive substantial heating and escape on close-in, gaseous planets.

Keywords: Exoplanet evolution, Ultraviolet spectroscopy, Solar evolution