Sazuna/UAT_keywords huggingface dataset:
SiO v = 1 J = 5 → 4 Maser Emission from the Root of the "Water Fountain" Source W 43A. We report here the first mapping of SiO v = 1 J = 5 → 4 maser emission toward the "water fountain" source W 43A in order to explore the central stellar system driving the collimated, bipolar, fast jet. The maser source has a systemic line-of-sight velocity consistent with that of CO J = 2 → 1 emission tracing the jet within ∼2 km s‑1 but a velocity gradient opposite that of the jet. The dynamical center of the maser source is located within ∼10 mas (or ∼20 au) of the brightness peak of the central 1.3 mm continuum emission. The spatiokinematic properties of the SiO J = 5 → 4 and J = 1 → 0 masers suggest that they are associated with the root of a slow (10 km s‑1 &lt; Voutflow &lt;&lt; 100 km s‑1) outflow with a large opening angle, and the central stellar system is contained within the inner maser region (∼20 au) during a possible common-envelope evolution.

Keywords: Circumstellar masers, Stellar jets, Common envelope evolution, Stellar mass loss
Falling Threads during Solar Filament Eruptions. Mass drainage is frequently observed in solar filaments. During filament eruptions, falling material most likely flows along magnetic field lines, which may provide important clues for the magnetic structures of filaments. Here we study three filament eruptions exhibiting significant mass draining, often manifested as falling threads at a constant speed ranging between 30 and 300 km s‑1. We found that most of the falling material lands onto the hooked segments of flare ribbons, only a small fraction lands inside the hooks, and almost none lands onto the straight segments of ribbons. Based on these observations we surmise that before eruptions most of the filament mass is entrained by field lines threading the quasi-separatrix layers (QSLs), which wrap around the filament field and whose footpoints are mapped by the hooked ribbons, and that the magnetic reconnection involving these field lines is the major cause of the mass drainage during eruptions. Additionally, the light curves of the hooked ribbons suggest that during eruptions the earlier (later) QSL boundary of filaments is threaded by mass-loaded (depleted) field lines. By assuming that the constant-speed motion is due to a drag force balancing the gravity, we proposed a simplified analytical model to estimate the density contrast of the falling material. The estimated density contrast is then fed into a numerical model, in which filament threads fall along vertical magnetic field lines through a gravitationally stratified atmosphere. The resultant falling speeds, however, are short of observed values, which calls for further investigations.

Keywords: Solar flares, Solar filaments, Solar filament eruptions
Long-duration Nonthermal Motions in the Supra-arcade and Loop-top Region during an Eruptive Solar Flare. Solar flares are widely accepted to be powered by magnetic reconnection that involves complex dynamics in various scales. The flare supra-arcade and loop-top region, directly impacted by fast reconnection downflows, contains a wealth of microscopic dynamics, which are, however, difficult to resolve in imaging. We present simultaneous spectroscopic and imaging observations of hot flaring plasma above the loop tops by the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamics Observatory/Atmospheric Imaging Assembly. IRIS continuously observed high-temperature Fe XXI 1354.08 Å spectral emissions throughout the long-duration gradual phase of the X-class flare. We found weak Doppler blueshifts near the loop-top region, indicative of bulk plasma motions from chromospheric evaporation based on the three-dimensional flare loop orientation. Strong nonthermal velocities are detected at the bottom of the flare supra-arcade fan/plasma sheet, suggestive of the presence of turbulence in the flare current sheet region. In addition, disorganized nonthermal plasma motions are constantly detected until the very end of the flare, indicating irregular unresolved plasma flows in the cusp and loop-top region. The spatial and temporal evolution of spectral parameters follow the dynamics resulting from ongoing magnetic reconnection during the prolonged gradual phase. The long-lasting nonthermal plasma motions may contribute to the high and steady temperature of flaring plasmas above flare loops.

Keywords: Solar flares, Solar magnetic reconnection, Solar extreme ultraviolet emission, Solar flare spectra, Active solar corona
Intriguing Nature of AM Her–type Candidate CXOU J204734.8+300105. The detection and characterization of periodic X-ray signals are crucial for identifying new compact objects and studying the mechanisms powering their emission. We report on the timing and spectral variability of CXOU J204734.8+300105, a proposed eclipsing polar-type cataclysmic variable (CV) candidate. This source has been observed once with Chandra and twice with XMM-Newton, revealing several intriguing and conflicting features in its X-ray emission. The Chandra observation showed a periodicity of ∼6000 s with an eclipse-like feature. The X-ray light curve from the 2017 XMM-Newton observation showed a period of ∼2000 s without any apparent eclipse, while the simultaneous optical light curve from the Optical Monitor showed a period of ∼6000 s. This variability raises questions about the true nature of the source. Spectral analysis indicates a multicomponent emission and emission lines due to Fe. The spectral characteristics are consistent with those observed in other CV systems. Additionally, we identified optical and near-infrared counterparts from various catalogues. Our findings suggest a dynamic and evolving accretion environment of CXOU J204734.8+300105.

Keywords: Accretion, X-ray binary stars, White dwarf stars, X-ray sources, Compact objects, Cataclysmic variable stars
The Central Engine of Low-luminosity Radio Galaxy 3C 270 (NGC 4261). We present the polarization spectra of the nucleus of 3C 270. We confirm that the polarization angles of both the continuum and the emission lines are close to perpendicular to the jet direction after careful correction of interstellar polarization, which indicates polar scattering. The Stokes flux spectrum resembles the total flux spectrum, with no need for a broad component from the broad-line region. Over 94% of a sample of Seyfert I broad-line profiles would be significantly detected if present in our polarized flux spectrum. We favor the hypothesis that we are observing the continuum including any contribution from radiatively inefficient accretion flow and beamed synchrotron instead of a big blue bump, as well as the innermost narrow-line region, through reflection. This makes 3C 270 the third known case, after NGC 4258 and Centaurus A, where only narrow lines (and the continuum, if present) are scattered, with no evidence of an underlying big blue bump.

Keywords: Low-luminosity active galactic nuclei
Polarization Properties of Energetic Pulsars at Meterwavelengths. Polarization behavior shows a transition in the pulsar population, where energetic sources with higher spin-down energy loss,  Ė&gt;1034  erg s‑1, often have fractional linear polarization (L/I) close to 100%, while below this range L/I is usually lower than 50%. The polarization behavior has been primarily studied at higher frequencies above 1 GHz, and in this work, we explore the single-pulse polarization behavior in pulsars with  Ė&gt;5×1033  erg s‑1 at a lower frequency range of 300–750 MHz. The polarization behavior can be divided into two categories, the first with L/I &gt; 70% where the polarization position angle (PPA) follows a single track, and a second group with L/I &lt; 70% and scattered PPA behavior with or without orthogonal modes. However, there are some single pulses in the first category that also have lower L/I and exhibit the presence of two polarization modes along orthogonal tracks. The radio emission in pulsars arises due to coherent curvature radiation (CCR) from charge bunches, which develops due to nonlinear instabilities in the pulsar plasma forming charge separated envelope solitons. The CCR excites orthogonally polarized X and O modes oriented perpendicular and parallel to the magnetic field line planes, which detach in the plasma and propagate independently. The O mode is 7 times stronger than the X mode but gets damped in the medium. We show that incoherent mixing of the X and O modes with different levels of damping can reproduce the observed polarization features in the energetic pulsar population.

Keywords: Radio pulsars
Using Simulation-based Inference on Tidally Perturbed Dwarf Galaxies: The Dynamics of NGC 205. We develop a novel approach to performing precision inference on tidally perturbed dwarf galaxies. We use a Bayesian inference framework of implicit likelihood inference, previously applied mainly in the field of cosmology, based on forward simulation, data compression, and likelihood emulation with neural density estimators. We consider the case of NGC 205, a satellite of M31. NGC 205 exhibits an S-shape in the mean line-of-sight velocity along its semimajor spatial axis, suggestive of tidal perturbation. We demonstrate that this velocity profile can be qualitatively reproduced even if NGC 205 was in a spherically symmetric and isotropic state before its most recent pericenter passage. We apply our inference method to mock data and show that the precise shape of a perturbed satellite's sky-projected internal velocity field, mapped across its entire face, can be highly informative of both its orbit and total mass density profile, even in the absence of proper motion information. For NGC 205 specifically, our method is hampered because the available data only covers a line along its semimajor axis. This shortcoming could be addressed with another round of observations.

Keywords: Local Group, Computational astronomy, Dwarf galaxies, Astronomy data analysis, Galaxy kinematics
Hidden Population III Descendants in Ultrafaint Dwarf Galaxies. The elusive properties of the first (Population III or Pop III) stars can be indirectly unveiled by uncovering their true descendants. To this end, we exploit our data-calibrated model for the best-studied ultrafaint dwarf galaxy (UFD), Boötes I, which tracks the chemical evolution (from carbon to zinc) of individual stars from their formation to the present day. We explore the chemical imprint of Pop III supernovae (SNe), with different explosion energies and masses, showing that they leave distinct chemical signatures in their descendants. We find that UFDs are strongly affected by SN-driven feedback, resulting in a very low fraction of metals being retained by their gravitational potential well (&lt;2.5%). Furthermore, the higher the Pop III SN explosion energy, the lower the fraction of metals retained. Thus, the probability of finding descendants of energetic pair-instability SNe is extremely low in these systems. Conversely, UFDs are ideal cosmic laboratories for identifying the fingerprints of less massive and energetic Pop III SNe, through their [X/Fe] abundance ratios. Digging into the literature data for Boötes I, we uncover three hidden candidates for Pop III descendants: one monoenriched and two multienriched. These stars show the chemical signature of Pop III SNe in the mass range [20–65]M⊙, spanning a wide range of explosion energies [0.3–10]1051 erg. In conclusion, candidates for Pop III descendants are hidden in ancient UFDs, but those monoenriched by a single Pop III SN are extremely rare. Thus, self-consistent models such as the one presented here are required to uncover these precious fossils and probe the properties of the first Pop III SNe.

Keywords: Population III stars, Dwarf galaxies, Chemical abundances, Primordial galaxies, Chemical enrichment, Population II stars
The Density Distribution of Compressively Forced, Supersonic Turbulence Depends on the Driving Correlation Time. Supersonic turbulence plays a critical role in shaping astrophysical systems, from molecular clouds to the circumgalactic medium. Key properties of this turbulence include the Mach number, driving scale, and nature of the driving mechanism, which can be solenoidal (divergence-free), compressive (curl-free), or a mix of the two. A less studied property is the correlation time of the driving accelerations, τa. While this timescale has a minimal impact on solenoidally driven turbulence, we show that it has a strong impact on compressively driven turbulence. Using high-resolution simulations with tracer particles, we analyze the evolution of density fluctuations, focusing on the probability distribution function of the logarithmic density, s, and its rate of change,  dsdt,  and the conditional statistics of  dsdt  and  d2sdt2 . When the driving correlation time is comparable to the eddy turnover time, τa ≍ τe, compressive driving leads to the formation of large, low-density voids in which the variance of  dsdt  is large. These are directly linked to sustained accelerated expansions, which result in a strong correlation between density and the divergence of the driving acceleration field. In contrast, when τa ≍ 0.1 τe, compressive driving does not produce such voids, resulting in a narrower, less skewed distribution. We show using analytical estimates that τa may be significantly less than τe in supernova-driven turbulence, highlighting the need to better understand the role of the driving correlation time in shaping the density structure of turbulent astrophysical systems.

Keywords: Interplanetary turbulence, Interstellar medium
Resistive Collapse of 2D Nonrotating Magnetized Isothermal Toroids: Formation of Pseudodisks. The collapse of singular magnetized toroids is a natural representation of an early phase in star formation, bridging the prestellar and protostellar phases of the collapse of molecular cloud cores. We revisit the collapse study of A. Allen et al., now with explicit nonideal MHD (ohmic diffusivity η) and higher resolution using a code able to cover a broader range of the magnetization parameter H0. Galli–Shu equatorial pseudodisks form for all values of H0 and η, and the asymptotic central mass growth rate is  Ṁ*∼(a3/G)(1+H0) , where a is the isothermal sound speed, consistent with previous results and predictions. The explicit ohmic diffusivity makes the field line structure less radial than in previous work, connecting the pseudodisk more effectively to its surroundings. Matter can fall efficiently onto the pseudodisk surfaces, forming oblique shocks, where shock heating and large density gradients raise the possibility of rich astrochemistry. Pseudodisk size and structure are influenced by magnetic diffusivity. Force and velocity ratios were computed to explore the magnetic support within the pseudodisk and its induced reduction in infall velocity. Magnetic diffusivity was measured to control the strength of these effects and their location within the pseudodisk. The dependence of the field line configurations, pseudodisk structure, and velocity ratios on magnetic diffusivity has observable consequences for collapsing envelopes.

Keywords: Accretion, Magnetohydrodynamics, Star forming regions, Stellar physics, Star formation, Stellar accretion, Astrophysical fluid dynamics, Magnetohydrodynamical simulations
A Study of the Spectral Properties of Gamma-Ray Bursts with Main and Second Bursts. The origins of the main burst and second burst of gamma-ray bursts (GRBs) and the composition of their jets remain uncertain. To explore this complex subject more thoroughly, we conduct a spectral analysis on 18 GRBs with a main and a second burst observed by Fermi/Gamma-Ray Burst Monitor. First, we employ Bayesian time-resolved spectral analysis to compare the spectral components of the main and the second burst, finding that 83.3% of the main and second bursts contain a thermal component. In 67% of the GRBs, the thermal component gradually decreases from the main to the second burst and the number of spectra exceeding the "synchrotron line of death" is significantly higher in the main burst than in the second burst. Subsequently, we ascertain that for both the main and second bursts, 71.4% and 77.8% evolve in a similar fashion in terms of the low-energy spectral index α and the peak energy Ep, respectively. Of the GRBs 50.0% and 72.2% exhibit comparable correlations for flux–α and α–Ep, respectively. For flux–Ep both the main and second bursts show a positive correlation. Moreover, from the perspective of the temporal evolution of characteristic radii, the transition from the main to the second burst appears to be seamless. Finally, we find that both the main and the second burst follow the same Amati relation and Yonetoku relation. Our analysis strongly indicates that the second burst is a continuation of the main burst and is highly likely to share a common physical origin with it.

Keywords: Gamma-ray bursts
Forcing Planets to Evolve: Interactions between Uranus and Neptune at Late Stages of Dynamical Evolution. In early solar system numerical simulations, where chaos is a primary driver, it is difficult to explore parameter space in a systematic way. In such simulations, stable configurations are hard to come by, and often require special fine-tuning. In addition, it is infeasible to run suites of well-resolved, realistic simulations with a disk of massive particles to drive planetary evolution where enough particles remain to represent the trans-Neptunian populations to robustly statistically compare with observations. To complement state-of-the-art full N-body simulations, we develop a method to artificially control each planet's orbital elements independently from each other, which, when carefully applied, can be used to test a wider suite of models. We modify two widely used publicly available N-body integrators: (1) the C code, REBOUND, and (2) the FORTRAN code, Mercury6.2. We show how the application of specific fictitious forces within numerical integrators can be used to tightly control planetary evolution to more easily explore migration and orbital excitation and damping. This tool allows us to replicate the impact that a massive planetesimal disk would have on the planets, without actually including the massive planetesimals, thus decreasing the chaos and simulation runtime. We demonstrate the utility of this tool by applying it to the coupled orbital evolution of Uranus and Neptune, and show that Neptune's eccentricity damping and radial outward migration have the appropriate affect on Uranus' eccentricity.

Keywords: Dynamical friction, Planetary dynamics, N-body simulations
M Star Opacities: The B<SUP>3</SUP>Π─X<SUP>3</SUP>∆ Band System of TiO. The spectra of titanium monoxide (TiO) are used to classify M stars. TiO experimental cross sections based on a high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory are used for the analysis of the TiO B3Π─X3∆ transition ( γ'  system). The 3─2 and 4─3 vibrational bands are analyzed for the first time, and the analysis of the 2─1 band is revised. The transition dipole moment function from an ab initio calculation is used to calculate the band strengths. These band strengths are used to produce a B3Π─X3∆ line list for the vibrational levels v '≤4  and v″ ≤ 4, suitable for simulation of astronomical spectra.

Keywords: Molecular spectroscopy, Line positions, Line intensities
A Near-infrared Search for Helium in the Superluminous Supernova SN 2024ahr. We present a detailed study of SN 2024ahr, a hydrogen-poor superluminous supernova (SLSN-I), for which we determine a redshift of z = 0.0861. SN 2024ahr has a peak absolute magnitude of Mg ≍ Mr ≍ −21 mag, rest-frame rise and decline times (50% of peak) of about 40 and 80 days, respectively, and typical spectroscopic evolution in the optical band. Similarly, modeling of the UV/optical light curves with a magnetar spin-down engine leads to typical parameters: an initial spin period of ≍3.3 ms, a magnetic field strength of ≍6 × 1013 G, and an ejecta mass of ≍9.5 M⊙. Due to its relatively low redshift, we obtained a high signal-to-noise ratio near-IR (NIR) spectrum about 43 rest-frame days postpeak to search for the presence of helium. We do not detect any significant feature at the location of the He I λ2.058 μm feature and place a conservative upper limit of ∼0.05 M⊙ on the mass of helium in the outer ejecta. We detect broad features of Mg I λ1.575 μm and Mg II λ2.136 μm, which are typical of Type Ic SNe, but with higher velocities. Examining the sample of SLSNe-I with NIR spectroscopy, we find that, unlike SN 2024ahr, these events are generally peculiar. This highlights the need for a large sample of prototypical SLSNe-I with NIR spectroscopy to constrain the fraction of progenitors with helium (Ib-like) and without helium (Ic-like) at the time of explosion, and hence the evolutionary path(s) leading to the rare outcome of SLSNe-I.

Keywords: Helium-weak stars, Type Ic supernovae, Transient sources, Time domain astronomy, Spectroscopy, Supernovae, Near infrared astronomy
Discovery of a Periodic Radio Signal from the Formerly Radio-quiet γ-Ray Pulsar J0359+5414 with FAST. In this paper, we report the detection of a periodic radio signal from the radio-quiet γ-ray pulsar PSR J0359+5414, using the Five-hundred-meter Aperture Spherical radio Telescope. This pulsar has a rotational period of 79.42 ms determined in the γ-ray band by the Fermi satellite. Our results show that the period of the radio signal is consistent with that obtained in the γ-ray. The measured dispersion measure value of the pulsar is 89 ± 3 pc cm‑3, with an estimated average flux density of only ∼6 μJy. We compare the pulse profiles of the γ-ray and radio pulsars at two phases and find their phases and pulse widths to be similar. The radio emission may originate from the upper regions of the pulsar magnetosphere, near the γ-ray emission zone. This is consistent with the idea that the radio emission in young high- Ė  pulsars is produced near the null charge surface and the γ-ray emission zone.

Keywords: Gamma-ray astronomy, Radio telescopes, Radio pulsars
GRB 241030A: Multicomponent Origin of Early Emission from the Photosphere and Internal and External Shocks. We present a detailed analysis of the long-duration GRB 241030A detected by Swift. Thanks to the rapid response of the X-Ray Telescope (XRT) and Ultraviolet/Optical Telescope, the strongest part of the prompt emission of GRB 241030A has been well measured simultaneously from the optical to hard X-ray bands. The time-resolved WHITE band emission shows strong variability, largely tracing the activity of the prompt γ-ray emission, suggesting that it may also be produced by internal shocks too. The joint analysis of the XRT and Burst Alert Telescope data reveals the presence of a thermal component with a temperature of a few keV, which can be interpreted as the photosphere radiation, and the upper limit of the Lorentz factor of this region is found to range between approximately 20 and 80. The time-resolved analysis of the initial U-band exposure data yields a very rapid rise (∼t5.3) with a bright peak reaching 13.6 AB magnitude around 410 s, which is most likely attributed to the onset of the external shock emission. The richness and fineness of early observational data have made this burst unique for studying various radiation mechanisms of γ-ray bursts.

Keywords: Gamma-ray bursts