Sazuna/UAT_keywords huggingface dataset:
Accurate and Robust Stellar Rotation Periods Catalog for 82771 Kepler Stars Using Deep Learning. We propose a new framework to predict stellar properties from light curves. We analyze the light-curve data from the Kepler space mission and develop a novel tool for deriving the stellar rotation periods for main-sequence stars. Using this tool, we provide rotation periods for more than 80K stars. Our model, LightPred, is a novel deep-learning model designed to extract stellar rotation periods from light curves. The model utilizes a dual-branch architecture combining long short-term memory and transformer components to capture temporal and global data features. We train LightPred on self-supervised contrastive pretraining and simulated light curves generated using a realistic spot model. Our evaluation demonstrates that LightPred outperforms classical methods like the autocorrelation function in terms of accuracy and average error. We apply LightPred to the Kepler data set, generating the largest catalog to date. Using error analysis based on learned confidence and consistency metric, we were able to filter the predictions and remove stellar types with variability, which is different than spot-induced variability. Our analysis shows strong correlations between error levels and stellar parameters. Additionally, we confirm tidal synchronization in eclipsing binaries with orbital periods shorter than 10 days. Our findings highlight the potential of deep learning in extracting fundamental stellar properties from light curves, opening new avenues for understanding stellar evolution and population demographics.

Keywords: Light curves
Identifying Hierarchically Triple Star Systems with Gaia DR3 and LAMOST. Triple star systems are critical for understanding stellar dynamics and compact objects in astrophysics, yet confirmed hierarchical triples identified via spectroscopy remain limited. In this study, we identified 23 triple systems by cross matching the Gaia DR3 non-single-star catalog with Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR10 spectroscopic data, 18 of them are new discoveries. For two well-observed triples, we performed radial velocity curve fitting and light curve analysis to determine their orbital parameters, with inner and outer periods of 1.26 and 656 days for one triple, and 3.42 and 422 days for the other. And we compared the results with other studies. We also analyzed the radial velocities of these 23 tripls, revealing a range of ΔV from approximately 40–210 km s‑1. Due to spectral resolution and detection limitations, velocity differences below 45 km s‑1 in binaries and below 90 km s‑1 in the inner binaries of triple systems are challenging to detect. Consequently, our detection range for inner orbital periods is restricted to 0.2–20 days, with the highest efficiency for periods under 10 days. These findings underscore the advantage of spectroscopic observations for identifying triple systems with short inner orbital periods.

Keywords: Trinary stars, Light curves, Radial velocity, Multiple stars
The Stellar Disk Structure Revealed by the Mono-age Populations of the LAMOST Red Clump Star Sample. Understanding the structure of the Galactic disk is crucial for understanding the formation and evolutionary history of the Milky Way. This study examines the structure of the Galactic disk by analyzing a sample of 138,667 primary red clump (RC) stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and Gaia data sets. We have categorized these RC stars into mono-age populations and investigated their spatial distributions within the R–Z plane, estimating scale heights and lengths through the fitting of their vertical and radial density profiles. Our analysis indicates that the vertical profiles of these mono-age populations fit a dual-component disk model, where both components exhibit significant flaring, particularly in the outer disk regions. Within a constant Galactocentric radius R, the scale heights of the first component, representing the morphologically thin disk, rise with age. In contrast, the scale heights of the second component, corresponding to the morphologically thick disk, remain comparatively stable across different age groups. Additionally, the radial density profiles of both disk components predominantly peak within a radial range of 7.5–8.5 kpc. These findings underscore the importance of age as a crucial factor in shaping the spatial distribution and structural evolution of the Galactic disk, offering valuable insights into its complex dynamics and history.

Keywords: Milky Way disk, Galaxy structure, Milky Way evolution
Photometric Analysis of the Cataclysmic Variable Star LT Eri. LT Eri is a long-period eclipsing cataclysmic variable star (CV). This study investigates its outbursts, negative superhumps (NSHs), tilted-disk precession, eclipse-depth variations, and observed minus calculated (O – C) behavior, using photometric data from the Transiting Exoplanet Survey Satellite (TESS), the Zwicky Transient Facility, the All-Sky Automated Survey for Supernovae, and the American Association of Variable Star Observers. Our analysis reveals an outburst period of 14.7(31) days, with variable periods ranging from 11.62(4) to 22.15(13) days. Both long and short outbursts were detected, lasting approximately 18 and 10 days, respectively. Analysis of the TESS photometry shows that the NSH period is updated to 0.16265161(7) days, persists during the outburst, and its amplitude is correlated with the outburst phase. A suspected signal of tilted-disk precession with a period of 3.5781(6) days is also detected. Additionally, the eclipse depth shows a periodic variation of 3.6270(9) days, closely matching the tilted-disk precession period; however, no biperiodic variation is found, as seen in the dwarf nova HS 2325+8205, suggesting that this phenomenon is not universal. An O – C analysis reveals a weak oscillation with a period of 3.5772(6) days. Our superposition of sine curves consistent with the NSH period and amplitude, along with mean eclipse curves, produces periodic O – C variations with a period of 3.6666(2) days. This indicates that the observed periodic variations in O – C, often around the disk precession period in CVs, may result from the beat between the NSHs and the eclipse rather than actual variations in the accretion disk.

Keywords: Eclipsing binary stars, Cataclysmic variable stars
H<SUB>2</SUB> Chemistry and Protonation in the Dayside Venusian Upper Atmosphere. Although H2 is present in low concentrations, it critically controls the structure and composition of planetary upper atmospheres through protonation under solar extreme-ultraviolet and soft X-ray irradiation. Recent studies highlight the importance of protonation on Venus. As H2 concentrations in its upper atmosphere remain poorly constrained, we conduct a systematic model investigation of how the structure of the topside Venusian ionosphere responds to varying H2 distributions. Our model results suggest that protonated species could outnumber nonprotonated species in the topside ionosphere when ambient H2 concentrations exceed 5 ppm. Generally, increasing H2 concentrations enhances the degree of protonation, manifesting as elevated levels of most protonated species, while nonprotonated species are generally depleted due to rapid reactions with H2. These trends, however, are not universal; nonmonotonic variations among multiple species like OH+ and O  emerge, driven by the complex chemical network that intricately links species distributions throughout the upper atmosphere. The results presented here provide a foundation for improved characterization of hydrogen escape on Venus during its evolutionary history.

Keywords: Photoionization, Planetary ionospheres, Planetary atmospheres, Venus
A Small Brown Dwarf in an Aligned Orbit Around a Young, Fully Convective M Star. A star's spin─orbit angle can give us insight into a system's formation and dynamical history. In this paper, we use MAROON-X observations of the Rossiter─McLaughlin effect to measure the projected obliquity of the LP 261-75 (also known as TOI-1779) system, focusing on the fully convective M dwarf LP 261-75A and the transiting brown dwarf LP 261-75C. This is the first obliquity constraint of a brown dwarf orbiting an M dwarf and the seventh obliquity constraint of a brown dwarf overall. We measure a projected obliquity of   degrees and a true obliquity of   degrees for the system, meaning that the system is well aligned and that the star is rotating very nearly edge-on, with an inclination of 90° ± 11°. The system thus follows along with the trends observed in transiting brown dwarfs around hotter stars, which typically have low obliquities. The tendency for brown dwarfs to be aligned may point to some enhanced obliquity damping in brown dwarf systems, but there is also a possibility that the LP 261-75 system was simply formed aligned. In addition, we note that the brown dwarf's radius (RC = 0.9 RJ) is not consistent with the youth of the system or radius trends observed in other brown dwarfs, indicating that LP 261-75C may have an unusual formation history.

Keywords: M dwarf stars, Radial velocity, Brown dwarfs
The Orbits of Uranus, Its Satellites and Rings, the Gravity Field of the Uranian System, and the Orientation of the Poles of Uranus and Its Satellites. R. A. Jacobson determined the orbits of the Uranian satellites, the masses of Uranus and its satellites, and the orientation of the pole of Uranus from Earth-based astrometry, Earth-based ring occultations, and observations acquired with the Voyager 2 spacecraft. Subsequent to that publication, several observers obtained new astrometry, and some of the original astrometry was rereduced against the Gaia star catalog. Moreover, R. G. French et al. made a new determination of the orbits of the Uranian rings, the orientation of the Uranian pole, and the gravity harmonics of Uranus from the entire set of Uranian ring occultations. Here we report the results of an analysis that redetermined the Uranus and satellite masses, satellite orbits, and the orbit of Uranus. In addition, we obtained a value for the Uranus tidal dissipation factor and produced an independent determination of the Uranian ring orbits, Uranus pole direction, and Uranus gravity harmonics. We also developed new expressions for the orientations of the satellites. We processed all of the data from our previous work plus the new and rereduced astrometry and the ring occultations. We extended our data arc forward to 2016 and backward to 1847. Our new orbit for Uranus is an update of that in ephemeris DE440 incorporating the occultation data and Gaia astrometry. *©2024 California Institute of Technology. Government sponsorship acknowledged.

Keywords: Uranus, Uranian satellites
Time-series Spectroscopy and TESS Photometry of the Oscillating Eclipsing Algol System V389 Cassiopeiae. We present the results from a detailed analysis of our time-series spectroscopic observations and the Transiting Exoplanet Survey Satellite (TESS) photometric data of the eclipsing binary V389 Cas. The radial velocities (RVs) of the primary and faint secondary components were obtained from a total of 61 high-resolution spectra made between 2016 and 2019. The disentangling spectra were used to determine the effective temperature and projected rotational velocity of the primary star based on the χ2 fitting statistic, yielding Teff,1 = 7720 ± 200 K and  v1sinirot=59±7  km s‑1, respectively. The fundamental properties of V389 Cas were determined from the simultaneous analysis of our RV curves together with the TESS light curves. The fitting results indicate that V389 Cas is a semidetached eclipsing binary with masses of  M1=2.38‑0.08+0.06M⊙  and  M2=0.33‑0.01+0.01M⊙ , and radii of  R1=2.66‑0.08+0.06R⊙  and  R2=2.41‑0.04+0.03R⊙ . A total of 50 frequency signals are detected from the multifrequency analysis of the residuals of the out-of-eclipse light curves. According to the pulsation constants of two frequencies with an amplitude greater than 1.0 mmag (f2 = 28.3487 day‑1 and f3 = 25.6069 day‑1) and location in the Hertzprung–Russell diagram, the primary component of V389 Cas is a typical δ Sct-type pulsator.

Keywords: Eclipsing binary stars, Stellar oscillations, Fundamental parameters of stars
The James Webb Space Telescope Absolute Flux Calibration. III. Mid-infrared Instrument Medium Resolution Integral Field Unit Spectrometer. We describe the spectrophotometric calibration of the Mid-Infrared Instrument's (MIRI) Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope. This calibration is complicated by a time-dependent evolution in the effective throughput of the MRS; this evolution is strongest at long wavelengths, approximately a factor of 2 at 25 μm over the first 2 yr of the mission. We model and correct for this evolution through regular observations of internal calibration lamps. Pixel flat fields are constructed from observations of the infrared-bright planetary nebula NGC 7027, and photometric aperture corrections from a combination of theoretical models and observations of bright standard stars. We tie the 5–18 μm flux calibration to high signal-to-noise ratio (S/N; ∼600–1000) observations of the O9 V star 10 Lacertae, scaled to the average calibration factor of nine other spectrophotometric standards. We calibrate the 18–28 μm spectral range using a combination of observations of main belt asteroid 515 Athalia and the circumstellar disk around young stellar object SAO 206462. The photometric repeatability is stable to better than 1% in the wavelength range 5–18 μm, and the S/N ratio of the delivered spectra is consistent between bootstrapped measurements, pipeline estimates, and theoretical predictions. The MRS point-source calibration agrees with that of the MIRI imager to within 1% from 7 to 21 μm and is approximately 1% fainter than prior Spitzer observations, while the extended source calibration agrees well with prior Cassini Composite Infrared Spectrometer and Voyager Infrared Interferometer Spectrometer and Radiometer observations.

Keywords: Infrared spectroscopy, Flux calibration
The Lack of RR Lyrae Variables in Ultrafaint Dwarf Galaxy Sextans II. RR Lyrae in ultrafaint dwarf (UFD) galaxies, if found, would be valuable to constrain the distances of these UFD. In this work, we report our search of RR Lyrae in a recently discovered UFD—Sextans II. Based on multiband (griz) time-series archival DECam imaging data, we do not find any RR Lyrae in Sextans II. On the contrary, the sparse multiband DECam light curves allowed recovery of a known foreground RR Lyrae, BB Sex, which happened to fall within the DECam images, and its pulsation period was correctly identified. Therefore, it is possible that Sextans II lacks RR Lyrae, similar to several other fainter UFDs (with MV ≳ ‑5.0 mag) that do not have RR Lyrae.

Keywords: RR Lyrae variable stars, Dwarf galaxies, Wide-field telescopes
Near-infrared Integral-field Spectroscopy of the Wind Forming Region of CW Leo. The circumstellar envelope of the carbon star CW Leo exhibited various unexpected changes in recent optical imaging observations. We have performed a follow-up observation using the Near-infrared Integral-Field Spectrograph (NIFS) equipped on the Gemini-North telescope. We report the near-infrared counterparts of a local brightness peak in the optical at the stellar position of CW Leo. On the other hand, a second peak detected at short wavelengths in the J band coincides with the brightest, bluest position in the optical images. The absorption features in the K band are minimized at a radius of 0 2 from the predicted stellar position. The reduction of the absorption depths likely indicates dilution of the absorption features by thermal emission of dust grains newly formed at such a radius and heated by radiation from the central star. The broad absorption feature at 1.53 μm is significantly deeper than in template carbon stars, consistent with the presence of a substantial amount of circumstellar material around CW Leo. Its northeastern quadrant lacks circumstellar absorption features and scattered light in the near-infrared regime, which are possibly manifestations of its conical cavity in both gas and dust. In addition, a cross correlation of CO overtone bands indicates that the average expansion velocity of dust grains is smaller to the northern direction, likewise the velocity of transverse wind components derived using the differential proper motion of a circumstellar whirled pattern. The gradual brightening of CW Leo and the changes in its innermost circumstellar envelope need further continuous monitoring observations to properly understand its transitional phase toward the post-asymptotic-giant-branch stage.

Keywords: Circumstellar envelopes, Infrared spectroscopy, Evolved stars, Carbon stars, Adaptive optics, Asymptotic giant branch stars, Near infrared astronomy
Back-illuminated Light-spot-mapping Algorithm for Dual Rotation Robotic Fiber Positioners Based on an Artificial Probability Potential Field Method. Back-illuminated spot mapping is essential for observations with modern spectroscopic survey telescopes. In the fiber position detection system, after the fiber view camera (FVC) detects the positions of the light spots from the robotic fiber positioners (RFPs), these positions must be mapped to the RFPs individually to complete subsequent calculations of their operational data. The back-illuminated images captured by the FVC show thousands of small light spots, each only hundreds of microns in size, randomly distributed on a completely black background, making accurate one-to-one mapping to the actual RFP positions highly challenging due to the lack of additional RFP features. This study constructs an artificial probability potential field to calculate the likelihood of each light spot appearing in the patrol area of an RFP, employing a global probability potential energy optimization method to establish the optimal mapping relationship. The proposed method successfully maps all light spots in the closed-loop fiber positioning task and is ultimately applied to the fiber positioning system of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, achieving accurate mapping of 4000 RFPs on the focal plane. This algorithm effectively addresses challenges such as multitarget interference, uniform background, and RFP failures, providing a reliable approach for mapping the back-illuminated points of tens of thousands of dual-rotation RFPs without requiring special backlight designs in future spectral survey telescopes.

Keywords: Astronomical techniques, Astronomical instrumentation, Algorithms, Telescopes
Unveiling the Origins and Dynamics of the Hierarchical Triple Star System CN Lyn. In this study, we present a detailed analysis of CN Lyn, an overlooked triple star system, by combining spectroscopic data from the literature, photometric Transiting Exoplanet Survey Satellite data, and kinematic techniques. We updated the fundamental parameters of the known eclipsing components in the system with high precision. The chemical composition of both eclipsing components (Aab) and the third component (B) in the system were calculated with great accuracy. According to our analysis the mass, radius, and metallicity of the eclipsing components are  ,  , and   dex for Aa and  ,  , and   dex for Ab. The pair's age is   Gyr. The mass, radius, metallicity, and age for B are  ,  ,   dex, and   Gyr, respectively. It is also found that the triple system (AabB) satisfies the stability criteria for the hierarchical triple system. Kinematic and Galactic orbital parameters of CN Lyn were obtained from the astrometric and spectroscopic data of the system. Dynamical orbital analyses, taking into account the ages of the component stars in the central binary system (A), show that the CN Lyn originated at the metal-poor edge of the Galactic disk. The third component of the system was found to be a member of the halo population in terms of age, α elements, and metal abundance. Given the different chemical abundances and age of B compared to A, this suggests that the third component was captured by the central system in a region with weak gravitational interactions far beyond the Galactic disk.

Keywords: High resolution spectroscopy, Chemical abundances, Galaxy kinematics, Detached binary stars, Trinary stars, Metallicity
Discovery and Characterization of an Eccentric, Warm Saturn Transiting the Solar Analog TOI-4994. We present the detection and characterization of TOI-4994b (TIC 277128619b), a warm Saturn-sized planet discovered by the NASA Transiting Exoplanet Survey Satellite. TOI-4994b transits a G-type star (V = 12.6 mag) with a mass, radius, and effective temperature of  ,  , and Teff = 5640 ± 110 K. We obtained follow-up ground-based photometry from the Las Cumbres Observatory and the Antarctic Search for Transiting ExoPlanets telescopes, and we confirmed the planetary nature of TOI-4994b with multiple radial velocity observations from the Planet Finder Spectrograph, CHIRON, High Accuracy Radial velocity Planet Searcher, Fiber-fed Extended Range Optical Spectrograph, and CORALIE instruments. From a global fit to the photometry and radial velocities, we determine that TOI-4994b is in a 21.5 day eccentric orbit (e = 0.32 ± 0.04) and has a mass of  , a radius of  , and a Saturn-like bulk density of  . We find that TOI-4994 is a potentially viable candidate for follow-up stellar obliquity measurements. TOI-4994b joins the small sample of warm Saturn analogs and thus sheds light on our understanding of these rare and unique worlds. *This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Extrasolar gaseous planets, Exoplanets
A Well-Characterized Survey for Centaurs in Pan-STARRS1. To prepare for the upcoming Legacy Survey of Space and Time, we develop methods for quantifying the selection function of a wide-field survey as a function of all six orbital parameters and absolute magnitude. We perform a HelioLinC3D search for Centaurs in the Pan-STARRS1 detection catalog and use a synthetic debiasing population to characterize our survey's selection function. We find nine new objects, including Centaur 2010 RJ226, among 320 real objects, along with ∼70,000 debiasing objects. We use the debiasing population to fit a selection function and apply the selection function to a model Centaur population with orbital and size distributions from the literature. We confirm the model's marginal distributions but reject its joint distribution, and estimate an intrinsic population of 21,400  Centaurs with Hr &lt; 13.7. The discovery of only nine new objects in archival data verifies that the Pan-STARRS discovery pipeline had high completeness, but also shows that new linking algorithms can contribute even to traditional single-tracklet surveys. As the first systematic application of HelioLinC3D to a survey with extensive sky coverage, this project proves the viability of HelioLinC3D as a discovery algorithm for big-data wide-field surveys.

Keywords: Centaur group, Small Solar System bodies, Surveys, Astrostatistics, Trans-Neptunian objects, Algorithms