Sazuna/UAT_keywords huggingface dataset:
New Rotation Periods from the Kepler Bonus Background Light Curves. The Kepler field hosts the best-studied sample of field star rotation periods. However, due to Kepler's large 4″ pixels, many of its light curves are at high risk of contamination from background sources. The new Kepler Bonus Background light curves are deblended using a point-spread function algorithm, providing light curves of over 400,000 new background sources in addition to over 200,000 reanalyzed Kepler prime targets. These light curves provide the opportunity to search for new rotation periods. Here we apply a convolutional neural network trained on synthetic spot-modulated light curves to regress rotation periods from the Kepler Bonus light curves. We obtained periods for 32,159 total sources, 19,650 of which had previously been measured and 9811 of which are new periods for both Kepler prime and background sources. Our method also detected 608 pulsation frequencies from asteroseismic oscillations in red giants. We validate our Kepler prime periods against literature values and present the full period sample. We find excellent agreement with previously known literature periods, validating deep learning as a viable class of period determination methods. Comparing the periods and light curves of foreground–background pairs, we find that as many as 63% of periodic background light curves are still blended with the foreground, highlighting the limitations of the deblending technique.

Keywords: Stellar properties, Stellar populations, Light curves, Convolutional neural networks, Stellar physics, Stellar rotation
Surprising Spin–Orbit Resonances of Rocky Planets. Recent works suggest that, in multiplanetary systems, a close-in exoplanet can sometimes avoid becoming tidally locked to its host star if it is captured into a secular spin–orbit resonance with a companion planet. In such a resonance, the planet remains at a subsynchronous spin rate and an appreciable obliquity (the planet's spin–orbit misalignment angle). However, many of these works have only considered planets with fluid-like rheologies. Recent observations suggest that planets up to a few Earth masses may be rocky and thus may have an appreciable rigidity. In this work, we study the spin–orbit dynamics of such rigid planets using a linear dissipative tidal model and not enforcing principal-axis rotation about the body's shortest principal axis. We identify a new class of spin–orbit resonances when the planet spins at twice its orbital frequency. These resonances exist at nonzero obliquity and spontaneously excite non-principal-axis rotation upon resonance capture. While these resonances eventually disappear as tidal dissipation damps the obliquity to zero (and the body returns to principal-axis rotation), they still modify the spin evolutionary history of the planet. Such resonances may enhance the prevalence of secular spin–orbit resonances in exoplanetary systems.

Keywords: Exoplanet dynamics, Spin-orbit resonances, Super Earths
Circular Mystery: Exploring Diffuse Emission Surrounding a Radio Galaxy with uGMRT and VLA Multiwavelength Observations. We report the discovery of J1218+1813, a circular diffuse radio source detected in the Very Large Array (VLA) FIRST survey at 1400 MHz. The source has an angular diameter of approximately one arcminute, corresponding to a physical size of ∼180 kpc, and is associated with an elliptical galaxy with a redshift of z = 0.139635. To investigate its nature, we conducted a comprehensive multiwavelength analysis spanning both high and low radio frequencies, utilizing the VLA in C-configuration at L, C and X bands, along with the upgraded Giant Metrewave Radio Telescope (uGMRT) at bands 3 (250–500 MHz), 4 (550–850 MHz), and 5 (1000–1260 MHz). A spectral study based on these multiwavelength observations reveals that the core of J1218+1813 exhibits a steep spectral index of 0.8, indicating that the emission is dominated by optically thin synchrotron radiation. The spectral index varies between 1.1 and 1.8, from the inner to the outer structure, with the steepest values observed at the periphery of the diffuse emission. An optical analysis of the central host galaxy using spectroscopic data is also performed. The estimated black hole mass is 2.8 ± 0.8 × 108 M⊙, while the host galaxy has a stellar mass of 2.9 × 1011 M⊙ and a stellar age of 8.58 Gyr. The identification of J1218+1813 is particularly significant because it provides insight into the mechanisms responsible for the formation of circular diffuse radio structures surrounded by an elliptical galaxy. Potential formation scenarios for J1218+1813 are discussed in this paper.

Keywords: Active galaxies, Active galactic nuclei, Radio continuum emission, Radio astronomy, Radio sources
A Pilot Method to Determine the High Mass End of the Stellar Initial Mass Function in Galaxies Using UVIT, Hα-MUSE Observations and Applied to NGC 628. We present a pilot method to estimate the high-mass initial mass function (IMF) across the arm, interarm, and spur regions in galaxies and apply it to NGC 628. We extracted star-forming complexes (SFCs) from the Hα Very Large Telescope/Multi Unit Spectroscopic Explorer and Ultraviolet Imaging Telescope (far-ultraviolet (FUV) and near-ultraviolet (NUV)) observations of NGC 628 and used Atacama Large Millimeter/submillimeter Array observations to define the molecular gas distribution. We find that the extinction-corrected Hα and FUV luminosities correlate well. Using the fact that O stars have a shorter lifetime (107 yr) compared to B stars (108 yr), we estimated the approximate number of O stars from Hα emission, and the number of B0 (M* &gt; 10M⊙), and B1 (10M⊙ ≥ M* ≥ 3M⊙) stars using FUV and NUV observations. We derived the IMF index (α) for different regions using O to B0 (α1) and B0 to B1 (α2) stellar ratios. Our findings indicate that if we assume Hα arises only from O8-type stars, the resulting α1 value is consistent with the canonical IMF index. It steepens when we assume O stars with masses up to 100 M⊙ with mean α1 = 3.16 ± 0.62. However, the α2 does not change for large variations in the O-star population, and the mean α = 2.64 ± 0.14. When we include only blue SFCs (FUV − NUV ≤ 0.3), mean α2 is 2.43 ± 0.06. The IMF variation for SFCs in arms and spurs is insignificant. We also find that α2 correlates with different properties of the SFCs, the most prominent being the extinction-corrected UV color (FUV − NUV).

Keywords: Initial mass function, Spiral galaxies, Star forming regions, Massive stars, Ultraviolet astronomy, Galaxies
Bursts of Star Formation and Radiation-driven Outflows Produce Efficient LyC Leakage from Dense Compact Star Clusters. The escape of LyC photons emitted by massive stars from the dense interstellar medium (ISM) of galaxies is a key bottleneck for cosmological reionization. The escape fraction varies significantly across and within galaxies, motivating further study of the underlying physical factors responsible for these trends. We perform radiation hydrodynamic simulations of idealized clouds with different gas surface densities (compactness) Σ ∼ 102–105 M⊙ pc‑2, meant to emulate star cluster-forming clumps ranging from conditions typical of the local Universe to the high ISM-pressure conditions encountered at high redshift. We find that dense compact star clusters with Σ ≳ 104 M⊙ pc‑2 efficiently leak LyC photons, with cloud-scale luminosity-weighted average escape fractions ≳80% as opposed to ≲10% for Σ ∼ 100 M⊙ pc‑2. This occurs due to higher star formation efficiencies and shorter dynamical timescales at higher Σ; the former results in higher intrinsic LyC emission, and the latter implies rapid evolution, with a burst of star formation followed by rapid gas dispersal, permitting high LyC escape well before the intrinsic LyC emission of stellar populations drop (∼4 Myr). LyC escape in dense clouds is primarily facilitated by highly ionized outflows driven by radiation pressure on dust with velocities ∼3 times the cloud escape velocity. We also vary the (assumed) dust abundances (Zd) and find a mild increase (∼10%) in the escape fraction for ∼100 lower Zd. Our results suggest a scenario in which localized compact bursts of star formation in galaxies are disproportionately productive sites of LyC leakage. We briefly discuss possible observational evidence for our predictions and implications for cosmic reionization.

Keywords: Stellar feedback, Young star clusters, Interstellar medium, Reionization, High-redshift galaxies
Unveiling the Diversity of Type IIn Supernovae via Systematic Light-curve Modeling. Type IIn supernovae (SNe IIn) are a highly heterogeneous subclass of core-collapse supernovae, spectroscopically characterized by signatures of interaction with a dense circumstellar medium (CSM). Here, we systematically model the light curves of 142 archival SNe IIn using the Modular Open Source Fitter for Transients. We find that the observed and inferred properties of SN IIn are diverse, but there are some trends. The typical supernova CSM is dense (∼10−12 g cm−3) with highly diverse CSM geometry, with a median CSM mass of ∼1 M⊙. The ejecta are typically massive (≳10 M⊙), suggesting massive progenitor systems. We find positive correlations between the CSM mass and the rise and fall times of SNe IIn. Furthermore, there are positive correlations between the rise time and fall times and the r-band luminosity. We estimate the mass-loss rates of our sample (where spectroscopy is available) and find a high median mass-loss rate of ∼10−2 M⊙ yr−1, with a range between 10−3 and 1 M⊙ yr−1. These mass-loss rates are most similar to the mass loss from great eruptions of luminous blue variables, consistent with the direct progenitor detections in the literature. We also discuss the role that binary interactions may play, concluding that at least some of our SNe IIn may be from massive binary systems. Finally, we estimate a detection rate of 1.6 × 105 yr−1 in the upcoming Legacy Survey of Space and Time at the Vera C. Rubin Observatory.

Keywords: Astronomy data modeling, Core-collapse supernovae, Light curves, Stellar mass loss, Supernovae
A Composite Broad-line Region in SDSS J1609+4902: A Double-peaked Disk Component and a Gaussian Component. The profiles of broad emission lines in active galactic nuclei (AGNs) provide critical insights into the geometry and kinematics of the broad-line region (BLR), which in turn influence the uncertainties in estimating the masses of central supermassive black holes. In this study, we report the discovery of a low-luminosity AGN, SDSS J1609+4902, in which the Hα line exhibits two distinct BLR components: a Gaussian component and an extremely broad double-peaked component. Follow-up observations conducted at the Lijiang Observatory in 2025 reveal that the line profile remains roughly unchanged, suggesting that this BLR structure may remain stable over a timescale of ∼10 yr. We find that the size of the central Gaussian (full width at half-maximum, FWHM ∼ 3000 km s‑1) component is consistent with the classical reverberation mapping correlation. In contrast, the asymmetric double-peaked wing (FWHM ∼ 23,000 km s‑1) likely originates from a disk-like BLR with an inner radius of approximately 70 gravitational radii. These results provide new constraints on the structure and dynamics of BLRs in AGNs and highlight the potential for long-term stability in such systems.

Keywords: Accretion, Supermassive black holes, Active galactic nuclei
Energetic Neutral Atom Fluxes from the Voyager 1 and 2 Directions. IBEX observes a globally distributed energetic neutral atom (ENA) flux from the heliosheath and very local interstellar medium (VLISM). Over a 14 yr period, Voyager 1 and Voyager 2 traversed the heliosheath from the termination shock to the heliopause. In situ observations from these spacecraft place important constraints on the parent ion populations of the ENAs from the heliosheath in two directions on the upwind side of the heliosphere, i.e., the direction of motion of the Sun in the local interstellar medium. In this study, an MHD model that is constrained by Voyager in situ observations is used to estimate the contribution from the heliosheath to the total ENA fluxes observed by IBEX. At energies greater than about 0.5 keV, the heliosheath provides a significant fraction of the observed ENA flux. However, at energies less than about 0.5 keV, the heliosheath provides an insignificant fraction of the observed ENA flux. These results are the same for both directions, and since the Voyager 1 and 2 directions are not particularly unique, the results are likely to be applicable for much of the upwind hemisphere. Fundamentally, it is the physics of the termination shock and the thickness of the heliosheath that determine the energy-dependent contributions to the observed ENA flux from this region. Because the heliosheath source is insignificant, most ENAs at energies less than about 0.5 keV probably come from the VLISM.

Keywords: Heliopause, Heliosphere, Fast solar wind, Solar wind, Solar wind termination, Pickup ions, Interstellar medium, Heliosheath
Repeated Tidal Interactions Between Stars and Supermassive Black Holes: Mass Transfer, Stability, and Implications for Repeating Partial Tidal Disruption Events. Stars orbiting supermassive black holes can generate recurring accretion flares in repeating partial tidal disruption events (TDEs). Here, we develop an efficient formalism for analyzing the time-dependent response of a star to the removal of a fraction (≲10%) of its mass. This model predicts that mass loss results in a decrease in the average density of low-mass (≲0.7M⊙) stars. In contrast, higher-mass stars exhibit an increase in their average density, such that the change is more pronounced for larger mass losses, and stars with masses ∼1.5‑2M⊙ experience the largest such increase. We predict that the final energy of the star post-mass-loss (i.e., the "surviving core") is effectively given by the binding energy of the original star interior to the radius from which mass is removed, i.e., the final core energy is agnostic to the process that removes the mass and—as a corollary—tidal heating is comparatively insignificant. We find excellent agreement between our predictions and one-dimensional Eulerian simulations of a star undergoing mass loss, and three-dimensional Lagrangian simulations of partial TDEs. We conclude that (1) partially disrupted stars are not significantly heated via tidal dissipation, (2) evolved and moderately massive (≳1.5M⊙) stars can most readily survive many repeated stripping events, and (3) progressively dimmer flares—observed in some repeating partial TDE candidates—could be explained by the increase in the density of the star post-mass-loss.

Keywords: Black hole physics, Supermassive black holes, Stellar structures, Hydrodynamics, Tidal disruption, Stellar oscillations
Evaluating the Effects of Thermal Processing on Nucleosynthetic Zinc Isotope Variations: Insights from Carbonaceous Chondrites Leachates. Variations in the nucleosynthetic isotope compositions of meteorites have been suggested to result from variable destruction of some presolar grains through thermal processing. This mechanism has furthermore been linked to volatile depletion in chondritic meteorites. As a moderately volatile element with variable nucleosynthetic isotope compositions, Zn potentially records both processes. Here, we present the nucleosynthetic Zn isotope compositions of leachates that target distinct mineral phases from four carbonaceous chondrites (CCs). The isotopic similarities between some leaching steps imply that different phases were partially homogenized, obscuring the original hosts of the neutron-rich (NR) Zn component that characterizes CCs. However, some leachates of the most primitive sample, Murchison CM2, display distinct Zn isotope compositions. The results reveal that the NR Zn was possibly hosted in silicate or oxide grains, which are similar or identical to the carriers of the bulk of the Zn. Multiple scenarios that simulate preferential Zn loss from such phases were modelled and compared to estimated compositions of thermally processed components in chondrites. The modelling suggests that variable extents of Zn depletion cannot account for the observed variations in nucleosynthetic Zn isotope compositions, implying that these characteristics are decoupled. Instead, distinct isotope compositions are required for the different Zn carriers depending on the chondrite group. The results thus suggest that thermal processing alone is not responsible for the observed nucleosynthetic Zn isotope variations. Rather, they most likely reflect temporal or spatial changes in the composition of the molecular cloud as the protoplanetary disk evolved, in line with other studies.

Keywords: Mass spectrometry, Chondrites, Carbonaceous chondrites, Solar system, Isotope shifts, Meteorites
Modeling Foreground Spatial Variations in 21 cm Gaussian Process Component Separation. The 21 cm line from neutral hydrogen captures rich cosmological information. However, the 21 cm signals are highly contaminated by foreground emission, making accurate component separation vital for cosmological analyses. Gaussian processes (GPs) have been utilized for component separation in 21 cm data analyses, exploiting the distinct spectral behavior of the cosmological and foreground signals, which are modeled through the GP covariance kernel. Previous approaches have employed a global GP kernel along all lines of sight (LoS). In this work, we study Bayesian approaches that allow for spatial variations in foreground kernel parameters, testing them against simulated H I intensity mapping observations, which measures the total H I intensity in large voxels. We consider a no-pooling (NP) model, treating each LoS independently by fitting for separate covariance kernels, and a hierarchical Gaussian process (HGP) model, allowing for variation in kernel parameters between different LoS, regularized through a global hyperprior. We find that including spatial variations in the GP kernel parameters results in a significant improvement in cosmological signal recovery, achieving up to a 30% reduction in the standard deviation of the residual distribution. Allowing for spatial variations also improves the recovery of the H I power spectra and wavelet scattering transform coefficients. While the NP model achieves superior recovery as measured by the residual distribution, it is computationally demanding, faces convergence challenges, and is prone to overfitting. The HGP model strikes a balance between accuracy and robustness. Further improvements to the HGP model will require more physically-motivated modeling of foreground spatial variations. Our code can be found in the following repository: https://github.com/dkn16/H21F.

Keywords: Cosmology, H I line emission, Gaussian Processes regression, Large-scale structure of the universe
Anisotropic Diffusion of e<SUP>±</SUP> in Pulsar Halos over Multiple Coherence of Magnetic Fields. The slow particle diffusion in pulsar halos, inferred from TeV gamma-ray surface brightness profiles (SBPs), is attributed to cross-field diffusion under the anisotropic diffusion model. This model assumes sub-Alfvénic interstellar turbulence in the medium surrounding the pulsar and a rough alignment of the line of sight of observers toward the pulsar with the local mean magnetic field direction in the halo. In this model, the expected morphology of a pulsar halo is highly dependent on the properties of the interstellar magnetic field. We investigate the anisotropic diffusion of electron–positron pairs across multiple coherence of magnetic fields in pulsar halos in this work. We focus particularly on their influence on the predicted gamma-ray SBP and the asymmetry of the halo's morphology, as well as the observational expectations of the Large High Altitude Air Shower Observatory. Our results indicate that the requirement of a specific magnetic field geometry can be alleviated when accounting for a limited (and realistic) coherence length of the magnetic field in the model. Also, the halo's morphology may appear less asymmetric, especially after being smoothed by the point-spread function of instruments. This largely relaxes the tension between the asymmetric morphology of halos predicted by the model and the lack of apparent asymmetric halos detected so far. Our findings demonstrate the important influence of the coherence length of the interstellar magnetic field on the distribution of particles around their accelerators, and the consequence for the measured source morphology.

Keywords: Gamma-ray sources, Non-thermal radiation sources, Pulsar wind nebulae
Filamentary Hierarchies and Superbubbles. I. Characterizing Filament Properties across a Simulated Spiral Galaxy. High-resolution surveys reveal that the interstellar medium in the Milky Way and nearby galaxies consists of interlinked hierarchies of filamentary structure and superbubbles extending from galactic to subparsec scales. The characterization of filament properties across this hierarchy is of fundamental importance for the origin of giant molecular clouds and their star clusters. In this paper, we characterize the properties of filaments greater than 25 pc in length that are produced in the multiscale galactic MHD simulations of B. Zhao et al. By adapting the FilFinder algorithm of E. W. Koch &amp; E. W. Rosolowsky, we extract over 500 filaments ranging up to 10 kpc in scale, to derive the probability distribution functions for filament masses and lengths, magnetic field orientations, and the gravitational stability and fragmentation patterns of filaments. We find power-law distributions for filament masses and lengths. The former has a power-law index αm = 1.85 that is nearly identical to that of observed giant molecular cloud (GMC) mass functions in extragalactic and Galactic surveys, suggesting that GMC properties are inherited from their host filaments. The fragmentation of magnetized filaments on 200 pc scales or less occurs when they exceed an average critical line mass, as predicted by theory. On larger scales, however, kiloparsec filaments form out of the cold neutral medium, and fragmentation follows local variations in the critical line mass along spiral arms or at the boundaries of superbubbles.

Keywords: Interstellar filaments, Interstellar magnetic fields, Giant molecular clouds, Star formation, Interstellar medium, Intercloud medium, Magnetohydrodynamical simulations
Cellular Dynamics of Helium-rich Detonation on Sub-Chandrasekhar Mass White Dwarf. In previous hydrodynamic studies on detonation in the context of Type Ia supernovae (SNe Ia), consideration of cellular structures has been limited in the evaluation of a criterion in initiation, propagation, quenching, and the resolution requirement of detonation, whereas it is quite common to consider cell sizes in the discussion on terrestrial detonation in chemically reactive systems. In our recent study, the terrestrial cell-based theories, which incorporate the cell-size data acquired in two-dimensional simulations of helium detonation in the double-detonation model, were demonstrated to be powerful diagnostics in reproducing the thresholds in the initiation and quenching provided by previous studies. In the present study, two-dimensional simulation results of the cellular detonation in the base of a white dwarf's (WD) envelope are described in detail, in terms of the dynamic wave morphology and chemical abundance structure. The cellular structure is observed at a range of upstream density and envelope composition explored in the present work. C/O contamination by the WD's core material reduces the cell width rapidly, as accelerated by the α-capture reaction. It is also indicated that nickel production could be significantly delayed for the C/O-rich composition. The small cell width requires the detonation structure to be resolved in full-star simulations of SNe Ia, which could raise concerns about the robustness of the outcomes of some numerical simulations in terms of the success and failure of detonation. This issue may be overcome by subgrid modeling that incorporates the cellular dynamics acquired in resolved simulations.

Keywords: Type Ia supernovae