Sazuna/UAT_keywords huggingface dataset:
New Libraries of Nonlocal Thermodynamic Equilibrium Model Spectra for O and Early-B Stars. A new set of stellar spectral models is generated from nonlocal thermodynamic equilibrium metal line-blanketed model atmospheres of T. Lanz &amp; I. Hubeny. The new libraries present spectra in the effective temperature range from 15,000 to 55,000 K, for 8 metallicities, Z/Z⊙ = 2, 1, 0.5, 0.2, 0.1, 0.0032, 0.02, and 0.01; all of them for three microturbulent velocities, vturb = 2, 5, and 10 km s‑1; between 200 Å and 32 μm, and with resolution R = 100,000. The wavelength range supports ground-based optical/NIR, Hubble Space Telescope UV to NIR, as well as JWST NIR/MIR wavelength ranges fully. All models have the same vacuum wavelength scale with 739,791 sample points.

Keywords: Early-type stars
The Membership and Age of the Planet-hosting Young Star IRAS 04125+2902. A transiting planet was recently discovered around a star in the Taurus star-forming region, IRAS 04125+2902, making it one of the youngest known planets. The discovery paper cited two age estimates for IRAS 04125+2902, one based on a comparison to two sets of model isochrones in the Hertzsprung─Russell diagram and a second age reported by an earlier study for a putative population in Taurus that includes IRAS 04125+2902 (D4-North). However, the model isochrones in question differ significantly for most temperatures and luminosities of young low-mass stars, and do not reproduce the observed sequences for the TW Hya and 32 Ori associations (10 and 21 Myr). Meanwhile, as found in my previous work, D4-North is a collection of field stars and fragments of several distinct Taurus groups and older associations, so its quoted age is not meaningful. The true parent population for IRAS 04125+2902 is a small group that is ∼35 pc behind the L1495 and B209 clouds (B209N). I have analyzed the age of B209N through a comparison to TW Hya and 32 Ori. The M-star sequences in the latter two associations have the same shapes, but the sequence for B209N is flatter, indicating that &gt;M4 stars at ages of &lt;10 Myr fade more quickly than stars at earlier types and older ages. For the one member of B209N that is earlier than M4 (IRAS 04125+2902), I estimate an age of 3.0 ± 0.4 Myr based on its offsets from TW Hya and 32 Ori, which by happenstance is similar to the value derived through the comparison to model isochrones. *Based on observations made with the Gaia mission, the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer, and the NASA Infrared Telescope Facility.

Keywords: Star forming regions, Stellar ages, Planet hosting stars
The Effects of the Carbon-to-oxygen Ratio on the Condensate Compositions around Solar-like Stars. The initial stellar carbon-to-oxygen (C/O) ratio can have a large impact on the resulting condensed species present in the protoplanetary disk and, hence, the composition of the bodies and planets that form. The observed C/Os of stars can vary from 0.1–1. We use a sequential dust condensation model to examine the impact of the C/O on the composition of solids around a solar-like star. We utilize this model in a focused examination of the impact of varying the initial stellar C/O to isolate the effects of the C/O in the context of solar-like stars. We describe three different system types in our findings. The solar system falls into the silicate-dominant, low-C/O systems which end at a stellar C/O somewhere between 0.52 and 0.6. At C/Os between about 0.6 and 0.9, we have intermediate systems. Intermediate systems show a decrease in silicates while carbides begin to become significant. Carbide-dominant systems begin around a C/O of 0.9. Carbide-dominant systems exhibit high carbide surface densities at inner radii with comparable levels of carbides and silicates at outer radii. Our models show that changes between C/O = 0.8 and C/O = 1 are more significant than previous studies, that carbon can exceed 80% of the condensed mass, and that carbon condensation can be significant at radii up to 6 au.

Keywords: Extrasolar rocky planets, Carbon planets, Stellar abundances, Astrochemistry, Planet hosting stars, Exoplanet structure
Giant Molecular Clouds in RCW 106 (G333): Galactic Mini-starbursts and Massive Star Formation Induced by Supersonic Cloud–Cloud Collisions. To reveal the origin of the mini-starbursts in the Milky Way, we carried out large-scale CO observations toward the RCW 106 giant molecular cloud (GMC) complex using the NANTEN2 4 m radio telescope operated by Nagoya University. We also analyzed the Mopra Southern Galactic Plane CO survey and Herschel infrared continuum archival data. The RCW 106 GMC complex contains the radial velocity components of ‑68 km s‑1 and ‑50 km s‑1 reported by H. Nguyen et al. (2015). Focusing on the RCW 106 East and West region with the massive star formation having the bright infrared dust emission, we found that these regions have three different velocity components with ∼10 km s‑1 differences. The two out of three velocity components show morphological correspondence with the infrared cold dust emission and connect with the bridge feature on a position–velocity diagram. Therefore, two molecular clouds with ∼10 km s‑1 differences are likely to be physically associated with massive star-forming regions in the GMC complex. Based on these observational results, we argue that mini-starbursts and massive star/cluster formation in the RCW 106 GMC complex are induced by supersonic cloud–cloud collisions in an agglomerate of molecular gas on the Scutum–Centaurus arm.

Keywords: Molecular gas, Molecular clouds, Giant molecular clouds, Milky Way disk, Interstellar clouds, CO line emission
The Gl 229 System Revisited with the Line-by-line Framework: Planetary Signals Now Appear as Stellar Activity Ghosts. Gl 229 is a well-known system hosting the first confirmed brown dwarf (BD), Gl 229 B, discovered in 1995. Subsequent radial velocity (RV) follow-up of the star unveiled, in 2014, an exoplanet on a 471 days orbit with a minimum mass of ∼32 M⊕. In 2020, a second exoplanet with a 122 days orbital period and a minimum mass of approximately 7 M⊕ was reported. With its BD, now a known binary, and two exoplanets, Gl 229 has been deemed one of the most diverse systems and has sparked discussions regarding the different formation mechanisms that could have taken place around this star. This work presents a new analysis of the publicly available Gl 229 High Accuracy Radial Velocity Planet Searcher data reduced with the line-by-line precision RV algorithm resistant to spectral outliers. We find strong evidence for stellar activity impacting RV measurements. Stellar activity-induced RVs were modelled with a Gaussian process trained on the activity indicator provided by the algorithm, revealing the star's rotation period at 28.9 ± 1.6 days. We show that systematic errors and stellar activity are the most likely cause of the previously reported exoplanet signals. Our analysis provides a 3σ upper limit of 9.1 M⊕ for a planet in the system's habitable zone except for the periods close to the star's rotation period, where stellar activity worsens the limit to around 15 M⊕.

Keywords: M dwarf stars, Brown dwarfs, Exoplanet systems, Stellar activity, Planetary system formation, Exoplanet evolution, Radial velocity, Exoplanet formation
A Centroiding Algorithm for Point-source Trails. Astrometric measurements are significantly challenged by the relative motion between the point source and the telescope, primarily due to the difficulty in accurately determining the position of the point source at the mid-exposure moment. Especially when the trail is irregular in shape or results from nonuniform relative motion, determining the centroid of such a trail becomes significantly more challenging. To address this issue, a new centroiding algorithm for point-source trails has been developed. This algorithm employs a piecewise linear model to approximate the irregular trajectory of a point source. An estimated intensity distribution of the trail is constructed by integrating the point-spread function with the approximated trajectory. The cost function is defined as the difference between the estimated and observed trail intensity distributions, with an added smoothness constraint term. Optimizing this cost function yields a refined trajectory fit. A coarse-to-fine iterative approach is used to progressively converge on the true trajectory of the point source, ultimately determining both the trail's centroid and the trajectory of the point source. The efficacy of the algorithm is validated using synthetic images. Furthermore, this technique is applied to Cassini Imaging Science Subsystem images of several inner Saturnian satellites, successfully processing 267 astrometric observations. The results demonstrate the effectiveness of the algorithm in real astronomical applications.

Keywords: Observational astronomy, Ephemerides, Astrometry, Saturnian satellites, Astronomy image processing
Emission from Multiple Molecular Isotopologues in a High-inclination Protoplanetary Disk. We present a MIRI-MRS spectrum of the high-inclination protoplanetary disk around the solar-mass (K0) star MY Lup, obtained as part of the JWST Disk Infrared Spectral Chemistry Survey (JDISCS). The spectrum shows an unusually weak water emission spectrum for a disk around a star of its spectral type, but strong emission from CO2, HCN, and isotopologues of both molecules. This includes the first ever detection of C18O16O and H13CN in an inner disk, as well as tentative detections of C17O16O and HC15N. Slab modeling provides the molecular temperatures, column densities, and emitting areas of the detected molecules. The emitting molecular gas is cold compared to that of other observed protoplanetary disk spectra. We estimate the isotopologue ratios of CO2 and HCN, albeit with significant uncertainty. We suggest that the unusual spectrum of MY Lup arises from a combination of inner-disk clearing, which removes emission from warm water, and its nearly edge-on inclination, which enhances line-of-sight column densities, although unusual chemistry may also be required. MY Lup's spectrum highlights the potential to detect and measure trace isotopologues to study isotopic fractionation in protoplanetary disks; observations at higher spectral resolving power are needed to constrain the isotopologue ratios to greater precision.

Keywords: Exoplanet formation, Molecular spectroscopy, Protoplanetary disks
Resolved Stellar Mass Estimation of Nearby Late-type Galaxies for the SPHEREx Era: Dependence on Stellar Population Synthesis Models. The upcoming all-sky infrared spectrophotometric SPHEREx mission is set to provide spatially resolved stellar mass maps of nearby galaxies, offering more detailed insights than integrated light observations. In this study, we develop a strategy for estimating stellar mass using SPHEREx by examining the dependence on different stellar population synthesis (SPS) models and proposing new scaling relations based on simulated SPHEREx data. We estimate the resolved stellar masses of 19 nearby late-type galaxies from the PHANGS-MUSE survey, treating these as fiducial masses. By testing four SPS models covering infrared wavelengths, i.e., E-MILES, Bruzual &amp; Charlot (BC03), Charlot &amp; Bruzual (CB19), and FSPS, we find systematic differences in mass-to-light ratios at 3.6 μm (M*/L3.6 μm) among the SPS models. In particular, BC03 and CB19 yield mass-to-light ratios on average ∼0.2−0.3 dex lower than those from E-MILES and FSPS. These mass-to-light ratios strongly correlate with stellar age, indicating a significant impact of young stellar populations on stellar mass measurements. Our analysis, incorporating fiducial masses and simulated SPHEREx data, identifies the 1.6 μm band as the optimal wavelength for stellar mass estimation, with the lowest scatter (0.15−0.20 dex) of the stellar mass. This scatter can be further reduced to 0.10−0.12 dex across all SPS models by incorporating optical and SPHEREx colors. These results can provide guidance for measuring the stellar masses of the numerous nearby galaxies that SPHEREx will survey.

Keywords: Late-type galaxies, Galaxy stellar content
The Baryonic Tully─Fisher Relation. II. Stellar Mass Models. We present new color─ϒ* (mass-to-light ratio) models to convert Wide-field Infrared Survey Explorer W1 fluxes into stellar masses. We outline a range of possible star formation histories and chemical evolution scenarios to explore the confidence limits of stellar population models on the value of ϒ*. We conclude that the greatest uncertainties (around 0.1 dex in ϒ*) occur for the bluest galaxies with the strongest variation in recent star formation. For high-mass galaxies, the greatest uncertainty arises from the proper treatment of bulge─disk separation in which to apply different ϒ* relations appropriate for those differing underlying stellar populations. We compare our deduced stellar masses with those deduced from Spitzer Space Telescope 3.6 μm fluxes and stellar mass estimates in the literature using optical photometry and different ϒ* modeling. We find the correspondence to be excellent, arguing that rest-frame near-IR photometry is still more advantageous than other wavelengths.

Keywords: Galaxy photometry
Searching for GEMS: TOI-5688 A b, a Low-density Giant Orbiting a High-metallicity Early M-dwarf. We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets (R ≳ 8 R⊕) through the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. The planet was discovered with the Transiting Exoplanet Survey Satellite, and characterized with ground-based transits from Red Buttes Observatory, the Table Mountain Observatory of Pomona College, and radial velocity (RV) measurements with the Habitable-Zone Planet Finder on the 10 m Hobby Eberly Telescope and NEID on the WIYN 3.5 m telescope. From the joint fit of transit and RV data, we measure a planetary mass and radius of 124 ± 24 M⊕ (0.39 ± 0.07 MJ) and 10.4 ± 0.7 R⊕ (0.92 ± 0.06 RJ), respectively. The spectroscopic and photometric analysis of the host star TOI-5688 A shows that it is a metal-rich ([Fe/H] = 0.47 ± 0.16 dex) M2V star, favoring the core-accretion formation pathway as the likely formation scenario for this planet. Additionally, Gaia astrometry suggests the presence of a wide-separation binary companion, TOI-5688 B, which has a projected separation of ~5″ (1110 au) and is an M4V, making TOI-5688 A b part of the growing number of GEMS in wide-separation binary systems. *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: M dwarf stars, Radial velocity, Transits, Extrasolar gaseous giant planets
AstroSat/UVIT Far- and Near-UV Deep Field Around IC 4329A. We present high-resolution near-ultraviolet (NUV) and far-ultraviolet (FUV) deep imaging of the field around the Seyfert galaxy IC 4329A based on five observations performed with the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat. The long exposures of 82.9 ks in the NUV (N245M; λmean = 2447 Å; ∆λ = 270 Å) and 92.2 ks in the FUV (F154W; λmean = 1541 Å; ∆λ = 380 Å) bands constitute the deepest observations with 5σ detection limits of AB magnitudes mNUV = 26.2 and mFUV = 25.7. Leveraging UVIT's excellent angular resolution (FWHM ∼ 1.2″-1.8″, we performed a detailed analysis of the IC 4329A field and detected (above the 5σ significance level) a total of 4437 and 456 sources in the NUV and FUV bands, respectively. A large number of these detected sources were previously unknown. We performed astrometry and photometry on all detected sources. By cross-matching our catalog with the Gaia-DR3 and XMM-Newton DR12 catalogs, we found 651 optical and 97 X-ray counterparts of our sources. Additionally, we explored the UV variability of point sources, identifying 28 NUV sources as variable with a significance above the 2.5σ level. Of these, only three sources exhibited variability in the FUV band. Utilizing the NUV and Gaia fluxes, we determined that two previously cataloged white dwarf candidates are misclassified. Furthermore, we highlight galaxies with atypical morphology, including ring-like structures, multiple compact central sources, bifurcating spiral arms, and so on. Follow-up optical spectroscopy and multiwavelength observations are imperative to further investigate the nature of the sources within this field.

Keywords: Catalogs, Active galaxies, X-ray sources, Ultraviolet photometry
Evidence for Primordial Alignment II: Insights from Stellar Obliquity Measurements for Hot Jupiters in Compact Multiplanet Systems. A significant fraction of hot Jupiters have orbital axes misaligned with their host stars' spin axes. The large stellar obliquities of these giants have long been considered potential signatures of high-eccentricity migration, which is expected to clear out any nearby planetary companions. This scenario requires that only isolated hot Jupiters be spin─orbit misaligned while those with nearby companions, which must have more quiescent histories, maintain low-obliquity orbits, assuming they formed aligned within their primordial protoplanetary disks. Investigations of this stellar obliquity─companionship connection, however, have been severely limited by the lack of hot Jupiters found in compact multiplanet systems. Here, we present the sky-projected stellar obliquity (λ) of a hot Jupiter with a nearby inner companion recently discovered by NASA's Transiting Exoplanet Survey Satellite: TOI-5143c. Specifically, we utilize the Doppler shadow caused by the planet's transit, enabled by the Rossiter─McLaughlin (RM) effect, to find that the planet is aligned with  . Of the exoplanets with RM measurements, TOI-5143c becomes just the third hot Jupiter with a nearby companion, and is part of the 19th compact multiplanet single-star system, with an RM measurement. The spin─orbit alignment of these 19 systems provides strong support for primordial alignment, and thus implies that large obliquities are gained primarily due to postdisk dynamical interactions such as those inherent to high-eccentricity migration. As such, the observed spin─orbit alignment of hot Jupiters with nearby companions affirms that some fraction of these giants instead has quiescent origins.

Keywords: Transits, Exoplanet astronomy, Exoplanet evolution, Radial velocity, Exoplanet formation, Extrasolar gaseous giant planets
Lunar Degree-2 Tidal Love Number Determination Based on Combination of Four-way Radiometric Tracking and LLR Data. Lunar tidal Love numbers ( ,  , and  ), critical for understanding lunar interior structures, are traditionally derived from methods such as lunar spacecraft radiometric tracking, Lunar Laser Ranging (LLR), and laser altimetry. The Chang'e 7 lander is expected to carry a radio transponder and a retroreflector. In order to assess the ability of the Chang'e 7 data to constrain these Love numbers, we conducted a numerical simulation based on a four-way relay tracking model in terms of different orbital inclinations, varying lander positions (nearside, south pole, and farside of the Moon), combined with LLR. Our simulation results demonstrate the effectiveness of the Chang'e 7 in determining tidal Love numbers, with a particular advantage for   and  . By combining the LLR data from the nearside and the south pole of the Moon as well as the four-way lander tracking data of Chang'e 7, the formal uncertainties of   and   are better than  , which is nearly 1 order of magnitude higher than the existing accuracy estimated by LLR alone ( ). For the lunar south pole region, four-way radiometric ranging can still offer higher sensitivity and a longer observation time compared to LLR. This is evident for measurements of  , despite the fact that radiometric ranging precision is an order of magnitude lower than that of LLR. This type of observation not only complements laser altimetry and LLR but also holds potential for application to other celestial bodies (e.g., Ganymede, Callisto, Mars) capable of supporting a landed mission.

Keywords: Lunar science
Statistical Reevaluation of the Ultra-short-period Planet Classification Boundary: Smaller Planets within 1 Day, Larger Period Ratios below 2 Days. Terrestrial worlds with P &lt; 1 day, known as ultra-short-period planets (USPs), comprise a physically distinct population whose origins may be attributed to various possible formation channels within multiplanet systems. However, the conventional 1 day boundary adopted for USPs is an arbitrary prescription, and it has yet to be evaluated whether this specific cutoff, or any alternatives, may emerge from the data with minimal assumptions. We accordingly present a statistical evaluation of the USP classification boundary for 376 multiplanet systems across Kepler, K2, and TESS. We find that USPs are smaller in size (p = 0.004) and exhibit larger period ratios with their immediate neighbors ( ; p &lt; 10‑4) when compared to non-USP short-period (1 &lt; P/days &lt; 5) worlds, and that these discrepancies rapidly transition toward statistical insignificance (p &gt; 0.05) at respective orbital periods of   day and   days (see Figure 3). We verify that these results are not driven by imprecise planetary parameters, giant companions, low-mass host stars, or detection biases. Our findings provide qualitative support for pathways in which proto-USPs are detached from companions and delivered to P ≲ 2 days via eccentric migration, while a subset of these objects near P ∼ 1 day experience subsequent orbital decay and refractory mass loss to become USPs. These results lend evidence toward an astrophysical basis for the 1 day USP cutoff and encourage consideration of an additional 2 day boundary within future investigations of USP architectures and evolutionary dynamics.

Keywords: Extrasolar rocky planets, Exoplanet dynamics, Exoplanet migration, Planetary system evolution, Exoplanets, Super Earths, Exoplanet systems, Exoplanet astronomy, Exoplanet evolution
An Embedded Disk (eDisk) in the IceAge: Investigating the Jet and Outflow from Ced 110 IRS4. We present a comprehensive study of the large-scale structure, jet and outflow morphology, and kinematics of the Class 0/I protostellar binary Ced 110 IRS4, using JWST NIRCam (F150W and F410M) and MIRI MRS observations from the JWST ERC program IceAge, along with Atacama Large Millimeter/submillimeter Array (ALMA) data from the Early Planet Formation in Embedded Disks (eDisk) program. NIRCam images, combined with ALMA continuum and CO data, reveal arc-like structures (∼1100 au), suggesting a dense envelope around the protostars. We detect disk shadows from both protostars in F150W. The MIRI MRS integral field unit data reveal a jet from both protostars in multiple [Fe II] lines, [Ar II] 6.99 μm and [Ne II] 12.81 μm, marking the first detection of a jet from the system. The [Fe II] (5.34 μm) jet from Ced 110 IRS4A has a width of ≤51 au at the protostellar location, with a large opening angle of 23° ± 4°. After inclination correction, the jet velocity is 124 km s‑1, corresponding to a dynamical timescale of 25 yr. The molecular H2 outflow displays a distinct morphology resembling two hemispheres placed back-to-back. The consistent H2 emission extent across transitions, differing from previous observations of protostellar outflows detected with JWST, suggests that MHD disk winds may not drive the observed outflow. We find that the upper limit to the width of the outflow at the protostellar location is 130 ± 10 au, which is smaller than the disk diameter of 183.4 ± 0.4 au but much larger than width of the [Fe II] jet.

Keywords: Protostars, Young stellar objects, Stellar jets, Stellar winds