Sazuna/UAT_keywords huggingface dataset:
Two Ultralow-mass-ratio Binary Systems at Critical Evolutionary Stages. In this paper, we present photometric observations and period analysis of two totally eclipsing binaries with extremely low-amplitude light curves. Both binaries exhibit typical W Ursae Majoris-type light curves with total eclipses, allowing for the precise determination of the mass ratios. Light-curve solutions were derived using the Python package PHysics Of Eclipsing BinariEs in combination with a Markov Chain Monte Carlo framework. Both WISE J053525.4–200442 (hereafter J053525) and ASASSN-V J175200.35+361805.2 (hereafter J175200) are identified as shallow contact binaries with ultralow mass ratios. Specifically, J053525 exhibits a mass ratio of q ≈ 0.124 and a marginal contact degree of f ∼ 22%, while J175200 has q ≈ 0.027 and a contact degree of f ∼ 13%. Notably, J175200 represents the most extreme mass ratio observed in contact binaries to date. However, due to degeneracies between mass ratio and third-light contributions in purely photometric analyses, the derived mass ratios should be interpreted as lower limits, especially for J175200. The evolutionary states of these systems differ significantly. For J053525, a long-term period decrease is detected, with the orbital period derivative calculated as  dPdt=‑1.99×10‑6day yr‑1 . In contrast, J175200 shows a period increase:  dPdt=1.93×10‑7day yr‑1 . These contrasting period trends may be indicative of ongoing mass transfer; however, alternative explanations such as third-body effects cannot be ruled out. Nevertheless, the combination of their ultralow mass ratios, shallow contact configurations, and apparent period evolution highlights their unique value in testing mass ratio theories and the thermal relaxation oscillation hypothesis.

Keywords: Close binary stars, Mass ratio, Contact binary stars, Semi-detached binary stars
Silkscreen: Direct Measurements of Galaxy Distances from Survey Image Cutouts. With upcoming wide field surveys from the ground and space, the number of known dwarf galaxies at ≲25 Mpc is expected to dramatically increase. Insight into their nature and analyses of these systems' intrinsic properties will rely on reliable distance estimates. Currently employed techniques are limited in their widespread applicability, especially in the semi-resolved regime. In this work, we turn to the rapidly growing field of simulation-based inference to infer distances and other physical properties of dwarf galaxies directly from multiband images. We introduce Silkscreen: a code leveraging neural posterior estimation to infer the posterior distribution of parameters while simultaneously training a convolutional neural network such that inference is performed directly on the images. Utilizing this combination of machine learning and Bayesian inference, we demonstrate the method's ability to recover accurate distances from ground-based survey images for a set of nearby galaxies (2 &lt; D(Mpc) &lt; 12) with measured SBF or TRGB distances. We discuss caveats of the current implementation along with future prospects, focusing on the goal of applying Silkscreen to large upcoming surveys, like the Legacy Survey of Space and Time. While the current implementation performs simulations and training on a per-galaxy basis, future implementations will aim to provide a broadly trained model that can facilitate inference for new dwarf galaxies in a matter of seconds using only broadband cutouts. We focus here on dwarf galaxies, but we note that this method can be generalized to more luminous systems as well.

Keywords: Convolutional neural networks, Galaxy distances, Dwarf galaxies, Sky surveys
The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets inside the Water Ice Line. We present statistical results from the Epoch of Giant Planet Migration RV planet search program. This survey was designed to measure the occurrence rate of giant planets interior to the water ice line of young Sun-like stars, compare this to the prevalence of giant planets at older ages, and provide constraints on the timescale and dominant inward migration mechanism of giant planets. Our final sample amounts to 85 single young (20─200 Myr) G and K dwarfs that we target across a 4 yr time baseline with the near-infrared Habitable-zone Planet Finder spectrograph at McDonald Observatory's Hobby-Eberly Telescope. As part of this survey, we discovered the young hot Jupiter HS Psc b. We characterize survey detection completeness with realistic injection-recovery tests and measure an occurrence rate of  1.9−1.4+2.6 % for intermediate-age giant planets ( 0.3MJ&lt;msini&lt;13MJ ) within 2.5 au. This is lower than the field age occurrence rate for the same planet masses and separations and favors an increase in the prevalence of giant planets over time from ∼100 Myr to several Gyr, although our results cannot rule out a constant rate. A decaying planet occurrence rate is, however, strongly excluded. This suggests that giant planets located inside the water ice line originate from a combination of in situ formation or early migration coupled with longer-term inward scattering. The completeness-corrected prevalence of young hot Jupiters in our sample is  1.5−1.1+2.2 % —similar to the rate for field stars—and the 95% upper limit for young brown dwarfs within 5000 days is &lt;3.6% . *Based on observations obtained with the Hobby-Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians-Universitaet Muenchen, and Georg-August Universitaet Goettingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Radial velocity, Exoplanet migration, Astrostatistics, Exoplanet evolution
The Multiband Imaging Survey for High-alpha PlanetS (MISHAPS). I. Preliminary Constraints on the Occurrence Rate of Hot Jupiters in 47 Tucanae. The first generation of transiting planet searches in globular clusters yielded no detections, and in hindsight only placed occurrence rate limits slightly higher than the measured occurrence rate in the higher-metallicity Galactic thick disk. To improve these limits, we present the first results of a new wide-field search for transiting hot Jupiters in the globular cluster 47 Tucanae (47 Tuc). We have observed 47 Tuc as part of the Multiband Imaging Survey for High-Alpha PlanetS. Using 24 partial and full nights of observations taken with the Dark Energy Camera on the 4 m Blanco telescope at Cerro-Tololo Interamerican Observatory, we perform a search on 19,930 stars in the outer regions of the cluster. Though we find no clear planet detections, by combining our result with the upper limit enabled by R. L. Gilliland et al.'s Hubble search for planets around an independent sample of 34,091 stars in the inner cluster, we place the strongest limit to date on hot Jupiters with periods of 0.8 ≤ P ≤ 8.3 days and 0.5RJup ≤ RP ≤ 2.0RJup of fHJ &lt; 0.11%, a factor of ∼4 below the occurrence rate in the Kepler field. Our search found 35 transiting planet candidates, though we are ultimately able to rule out each without follow-up observations. We also found four eclipsing binaries (EBs), including three previously uncataloged detached EB stars.

Keywords: Exoplanet astronomy, Transit photometry, Hot Jupiters, Globular star clusters
Seasonal Changes in the Atmosphere of HD 80606 b Observed with JWST's NIRSpec/G395H. High-eccentricity gas giant planets serve as unique laboratories for studying the thermal and chemical properties of H/He-dominated atmospheres. One of the most extreme cases is HD 80606 b—a hot Jupiter orbiting a Sun-like star with an eccentricity of 0.93—which experiences an increase in incident flux of nearly 3 orders of magnitude as the star─planet separation decreases from 0.88 au at apoastron to 0.03 au at periastron. We observed the planet's periastron passage using JWST's NIRSpec/G395H instrument (2.8─5.2 μm) during a 21 hr window centered on the eclipse. We find that, as the planet passes through periastron, its emission spectrum transitions from a featureless blackbody to one in which CO, CH4, and H2O absorption features are visible. We detect CH4 during postperiapse phases at 4.1─10.7σ depending on the phase and on whether a flux offset is included to account for NRS1 detector systematics. Following periapse, H2O and CO are also detected at 4.2─5.5σ and 3.7─4.4σ, respectively. Furthermore, we rule out the presence of a strong temperature inversion near the IR photosphere based on the lack of obvious emission features throughout the observing window. General circulation models had predicted an inversion during periapse passage. Our study demonstrates the feasibility of studying hot Jupiter atmospheres using partial phase curves obtained with NIRSpec/G395H.

Keywords: Exoplanet atmospheric composition , Exoplanets, Exoplanet atmospheric variability, Exoplanet astronomy, James Webb Space Telescope, Exoplanet atmospheres, Exoplanet atmospheric structure
The Transit Signal of KOI-1755 Originates from a Background Eclipsing Binary Star—Extracting the Light Curve of a Faint Background Star from Kepler Target Pixel File Data. KOI-1755 (KIC 5302006) was initially identified by the Kepler mission as a candidate exoplanet host but subsequently classified as a false positive due to suspected background contamination. The target star itself exhibits intrinsic stellar pulsations, accompanied by transit-like dimming events, complicating a straightforward identification of the signal source. In this study, we carried out a detailed pixel-level reanalysis of KOI-1755 using the Kepler Target Pixel Files (TPFs) to clarify the origin of these transit-like signals. Through careful pixel-level flux modeling, centroid shift measurements, and cross-matching with the Gaia DR3 catalog, we conclusively determined that the dimming signals originate from a faint background eclipsing binary (EB), rather than KOI-1755 itself. We then developed a specialized photometric method to effectively remove contamination from nearby stars, allowing us to reliably extract the EB's uncontaminated light curve directly from the TPFs data. Analysis of this extracted light curve confirmed the contaminating source to be an EB system composed of two dwarf stars with a clear eclipse period of approximately 6.14 days. Our study provides a concrete example of how background EBs can mimic planetary transit signals, highlighting the importance of detailed pixel-level analyses for correctly identifying astrophysical false positives. Furthermore, our method demonstrates significant potential for uncovering previously hidden variable-star information within archival Kepler data, thus emphasizing the continuing scientific value of mining and reanalyzing existing data sets.

Keywords: Delta Scuti variable stars, Binary stars, Exoplanets
Near-infrared Polarimetry of the Massive Young Star W33A in the Godzilla Nebula: Detection of Linear and Circular Polarization. We have performed the first near-infrared linear and circular imaging polarimetry of the massive W33A star-forming region. Large linear polarization is detected in the very red and extended (∼1 pc projected length) infrared nebulae with a centrosymmetric pattern, suggesting that the IR nebula associated with W33A is the reflection nebula illuminated by the W33A IR source. There is a &lt;10,000 au-scale polarization disk in the vicinity of W33A, probably corresponding to a large pseudodisk. Similar to the other young stars, the circular polarization (CP) image shows a quadrupolar structure around the W33A IR source. However, its degrees are smaller than those previously reported for massive stars. The detection of CP suggests that the origin of CP around young stars is not simple but can be a combination of several causes.

Keywords: Polarimetry
HD 35843: A Sun-like Star Hosting a Long-period Sub-Neptune and Inner Super-Earth. We report the discovery and confirmation of two planets orbiting the metal-poor Sun-like star HD 35843 (TOI 4189). HD 35843 c is a temperate sub-Neptune transiting planet with an orbital period of 46.96 days that was first identified by Planet Hunters TESS. We combine data from TESS and follow-up observations to rule out false-positive scenarios and validate the planet. We then use ESPRESSO radial velocities (RVs) to confirm the planetary nature and characterize the planet's mass and orbit. Further analysis of these RVs reveals the presence of an additional planet, HD 35843 b, with a period of 9.90 days and a minimum mass of 5.84 ± 0.84 M⊕. For HD 35843 c, a joint photometric and spectroscopic analysis yields a radius of 2.54 ± 0.08 R⊕, a mass of 11.32 ± 1.60 M⊕, and an orbital eccentricity of e = 0.15 ± 0.07. With a bulk density of 3.80 ± 0.70 g cm−3, the planet might be rocky with a substantial H2 atmosphere or it might be a "water world." With an equilibrium temperature of ∼480 K, HD 35843 c is among the coolest ∼5% of planets discovered by TESS. Combined with the host star's relative brightness (V = 9.4), HD 35843 c is a promising target for atmospheric characterization that will probe this sparse population of temperate sub-Neptunes.

Keywords: High resolution spectroscopy, Exoplanets, Radial velocity, Exoplanet systems, Exoplanet astronomy, Planet hosting stars, Exoplanet detection methods, Transit photometry
The Compositions of Rocky Planets in Close-in Orbits Tend to Be Earth-like. Hundreds of exoplanets between 1 and 1.8 times the size of Earth have been discovered on close-in orbits. However, these planets show such a diversity in densities that some appear to be made entirely of iron, while others appear to host gaseous envelopes. To test this diversity in composition, we update the masses of five rocky exoplanets (HD 93963 A b, Kepler-10 b, Kepler-100 b, Kepler-407 b, and TOI-1444 b) and present the confirmation of a new planet (TOI-1011) using 187 high-precision radial velocities from Gemini/MAROON-X and Keck/KPF. Our updated planet masses suggest compositions closer to that of Earth than previous literature values for all planets in our sample. In particular, we report that two previously identified "super-Mercuries" (Kepler-100 b and HD 93963 A b) have lower masses that suggest less iron-rich compositions. We then compare the ratio of iron to rock-building species with the abundance ratios of those elements in their host stars. These updated planet compositions do not suggest a steep relationship between planet and host star compositions, contradictory to previous results, and suggest that planets and host stars have similar abundance ratios.

Keywords: Extrasolar rocky planets, Exoplanets, Super Earths, Exoplanet astronomy, Radial velocity
Velocity Shift and Signal-to-Noise Ratio Limits for High-resolution Spectroscopy of Hot Jupiters Using Keck/KPIC. High-resolution cross-correlation spectroscopy is a technique for detecting the atmospheres of close-in planets using the change in the projected planet velocity over a few hours. To date, this technique has most often been applied to hot Jupiters, which show a large change in velocity on short timescales. Applying this technique to planets with longer orbital periods requires an improved understanding of how the size of the velocity shift and the observational signal-to-noise ratio (SNR) impact detectability. We present grids of simulated Keck/Keck Planet Imager and Characterizer (KPIC) observations of hot Jupiter systems, varying the observed planet velocity shift and SNR, to estimate the minimum thresholds for a successful detection. These simulations realistically model the cross-correlation process, which includes a time-varying telluric spectrum in the simulated data and data detrending via principal component analysis. We test three different planet models based on an ultrahot Jupiter, a classical hot Jupiter, and a metal-rich hot Saturn. For a 6σ detection suitable for retrieval analysis, we estimate a minimum velocity shift of Δvpl ∼ 30, 50, 60 km s‑1, compared to an instrumental resolution of 9 km s‑1, and minimum SNR ∼ 370, 800, 1200 for the respective planet models. We find that reported KPIC detections to-date fall above or near the 6σ limit. These simulations can be efficiently rerun for other planet models and observational parameters, which can be useful in observation planning and detection validation.

Keywords: High resolution spectroscopy, Hot Jupiters, Exoplanet atmospheric composition , Exoplanet atmospheres
SETI@home: Data Analysis and Findings. SETI@home is a radio Search for Extraterrestrial Intelligence (SETI) project that looks for technosignatures in data recorded at the Arecibo Observatory. The data were collected over a period of 14 yr and cover almost the entire sky visible to the telescope. The first stage of data analysis found billions of detections: brief excesses of continuous or pulsed narrowband power. The second stage removed detections that were likely radio frequency interference (RFI), then identified and ranked signal candidates: groups of detections, possibly spread over the 14 yr, that plausibly originate from a single cosmic source. We manually examined the top-ranking signal candidates and selected a few hundred. In the third and final stage, we are reobserving the corresponding sky locations and frequency ranges using the Five-hundred-meter Aperture Spherical Telescope radio telescope. This paper covers SETI@home's second stage of data analysis. We describe the algorithms used to remove RFI and to identify and rank signal candidates. To guide the development of these algorithms, we used artificial candidate birdies that model persistent ET signals with a range of power, bandwidth, and planetary motion parameters. This approach also allowed us to estimate the sensitivity of our detection system to these signals.

Keywords: Radio spectroscopy, Search for extraterrestrial intelligence, Technosignatures, Radio astronomy
SETI@home: Data Acquisition and Front-end Processing. SETI@home is a radio Search for Extraterrestrial Intelligence (SETI) project, looking for technosignatures in data recorded at multiple observatories from 1998–2020. Most radio SETI projects analyze data using dedicated processing hardware. SETI@home uses a different approach: time-domain data is distributed over the internet to &gt;105 volunteered home computers, which analyze it. The large amount of computing power this affords (∼1015 floating-point operations per second (FPOP s–1)) allows us to increase the sensitivity and generality of our search in three ways. We use coherent integration, a technique in which data is transformed so that the power of drifting signals is confined to a single discrete Fourier transform (DFT) bin. We perform this coherent search over 123,000 Doppler drift rates in the range (±100 Hz s‑1). Second, we search for a variety of signal types, such as pulsed signals and arbitrary repeated waveforms. The analysis uses a range of DFT sizes, with frequency resolutions ranging from 0.075–1221 Hz. The front end of SETI@home produces a set of detections that exceed thresholds in power and goodness of fit. We accumulated ∼1.2 × 1010 such detections. The back end of SETI@home takes these detections, identifies and removes radio frequency interference, and looks for groups of detections that are consistent with extraterrestrial origin and that persist over long timescales. This paper describes the front end of SETI@home and provides parameters for the primary data source, the Arecibo Observatory; the back end and its results are described in a companion paper. * https://setiathome.berkeley.edu/

Keywords: Radio spectroscopy, Open source software, Astronomy software, Technosignatures, Astronomical instrumentation, Search for extraterrestrial intelligence, Radio astronomy
Multiple Machine Learning as a Powerful Tool for Star Cluster Analysis. This work proposes a multiple machine learning method (MMLM) aiming to improve the accuracy and robustness of the analysis of star clusters. The MMLM performance is evaluated by applying it to the reanalysis of an old binary cluster candidate—comprised of NGC 1605a and NGC 1605b—found by D. Camargo (2021; hereafter C21). The binary cluster candidate is analyzed by employing a set of well-established machine learning algorithms applied to the Gaia-EDR3 data. Membership probabilities and open clusters (OCs) parameters are determined by using the clustering algorithms pyUPMASK, ASteCA, k-means, GMM, and HDBSCAN. In addition, a KNN smoothing algorithm is implemented to enhance the visualization of features like overdensities in the 5D space and intrinsic stellar sequences on the color–magnitude diagrams. The method validates the clusters' previously derived parameters; however, it suggests that their probable member stars are distributed over a wider overlapping area. Finally, a combination of the elbow method, t-SNE, k-means, and GMM algorithms groups the normalized data into six clusters, following C21. In short, these results confirm NGC 1605a and NGC 1605b as genuine OCs and reinforce the previous suggestion that they form an old binary cluster in an advanced stage of merging after a tidal capture during a close encounter. Thus, MMLM has proven to be a powerful tool that helps to obtain more accurate and reliable cluster parameters, and its application in future studies may contribute to a better characterization of the Galaxy's star cluster system.

Keywords: Galaxy structure, Clustering, Open star clusters, Algorithms, Star clusters
Bringing the Norma Dark Cloud to Light in X-Rays. The filamentary dark cloud complex in Norma reveals signs of active low-mass star formation including protostars, Hα emission line stars, Herbig–Haro objects, and the eruptive FU Orionis-like star V346 Nor. We present results of the first pointed X-ray observations of the Norma dark cloud, focusing on the westernmost Sandqvist 187 region. Chandra detected 75 X-ray sources, and a complementary XMM-Newton observation detected 92 sources within the Chandra field of view, of which 46 are cross-matched to Chandra, yielding 121 unique X-ray sources. We present a catalog of X-ray sources along with basic X-ray properties and candidate IR and optical counterparts. Existing near-IR photometry reveals several X-ray sources with color excesses typical of young stars with disks. Gaia parallaxes single out foreground stars and X-ray sources at distances of 500–1000 pc that are probable cloud members. The known emission line stars Sz 136 and Sz 137 were detected but V346 Nor was not. Interestingly, the optical and IR counterparts of the brightest Chandra source are not known with certainty but the prime suspects are very faint. Thus, the nature of the object responsible for the bright X-ray emission remains speculative. The X-ray observations presented here will serve as a pathfinder for identifying and characterizing the young stellar population in the Norma dark cloud.

Keywords: Star forming regions, Pre-main sequence stars, Dark interstellar clouds