Sazuna/UAT_keywords huggingface dataset:
Nucleosynthesis Conditions in Outflows of White Dwarfs Collapsing to Neutron Stars. An accretion-induced collapse (AIC) or merger-induced collapse (MIC) of white dwarfs (WDs) in binary systems is an interesting path to neutron star (NS) and magnetar formation, alternative to stellar core-collapse and NS mergers. Such events could add a population of compact remnants in globular clusters; they are expected to produce yet unidentified electromagnetic transients including gamma-ray and radio bursts, and to act as sources of transiron elements, neutrinos, and gravitational waves. Here, we present the first long-term (≳5 s postbounce) hydrodynamical simulations in axisymmetry (2D), using an energy- and velocity-dependent three-flavor neutrino transport based on a two-moment scheme. Our set of six models includes initial WD configurations for different masses, central densities, rotation rates, and angular momentum profiles. Our simulations demonstrate that rotation plays a crucial role for the protoneutron star (PNS) evolution and ejecta properties. We find early neutron-rich ejecta and an increasingly proton-rich neutrino-driven wind at later times in a nonrotating model, in agreement with electron-capture supernova models. In contrast to that and different from previous results, our rotating models eject proton-rich material initially and increasingly more neutron-rich matter as time advances, because an extended accretion torus forms around the PNS and feeds neutrino-driven bipolar outflows for many seconds. AIC and MIC events are thus potential sites of r-process element production, which may imply constraints on their occurrence rates. Finally, our simulations neglect the effects of triaxial deformation and magnetic fields, yet they provide valuable reference cases for comparison with future long-term magnetohydrodynamic and 3D AIC studies.

Keywords: Neutron stars, Hydrodynamical simulations, Supernova neutrinos, Nucleosynthesis, White dwarf stars, Supernovae
A Parametric Study of Solar Wind Properties and Composition Using Fluid and Kinetic Solar Wind Models. The physical processes in the solar corona that shape the solar wind remain an active research topic. Modeling efforts have shown that energy and plasma exchanges near the transition region play a crucial role in modulating solar wind properties. Although these regions cannot be measured in situ, plasma parameters can be inferred from coronal spectroscopy and ionization states of heavy ions, which remain unchanged as they escape the corona. We introduce a new solar wind model extending from the chromosphere to the inner heliosphere, capturing thermodynamic coupling across atmospheric layers. By including neutral and charged particle interactions, we model the transport and ionization processes of the gas through the transition region and corona and into the solar wind. Instead of explicitly modeling coronal heating, we link its spatial distribution to large-scale magnetic field properties. Our results confirm that energy deposition strongly affects wind properties through key mechanisms involving chromospheric evaporation, thermal expansion, and magnetic flux expansion. For sources near active regions, the model predicts significant solar wind acceleration, with plasma outflows comparable to those inferred from coronal spectroscopy. For winds from large coronal holes, the model reproduces the observed anticorrelation between charge state and wind speed. However, the predicted charge state ratios are overall lower than observed. Inclusion of a population of energetic electrons enhances both heavy ion charge states and solar wind acceleration, improving agreement with observations.

Keywords: Solar wind, Solar corona, Ionization, Solar chromosphere, Astronomical simulations
SNR G54.1+0.3, a PeVatron Candidate Unveiled by LHAASO. Recently, the LHAASO Collaboration reported the first very-high-energy gamma-ray catalog, containing 90 TeV sources. Among these sources, 1LHAASO J1929+1846u is located 0 3 west of SNR G54.1+0.3 and also lies within a +53 km s‑1 cloud (the Western Cloud). Moreover, one of the IceCube track-type high-energy starting events is found around 1 3 north of 1LHAASO J1929+1846u, which may serve as strong evidence for the hadronic origin of this TeV source. SNR G54.1+0.3 is a young supernova remnant (SNR), with a powerful pulsar wind nebula (PWN) inside. Its X-ray radiation from the PWN and the SNR shell can be clearly identified. The radio emission from the PWN region is also given. However, given the angular resolution of gamma-ray experiments, the entire SNR region is viewed as a point source by the Fermi Large Area Telescope, High Energy Stereoscopic System, and VERITAS. In this work, we explore a hybrid scenario where SNR G54.1+0.3 is indeed associated with the Western Cloud, and we derive the multiwavelength emissions from the PWN, the SNR shell, and the Western Cloud, separately. Our model can explain the observations well, indicating that SNR G54.1+0.3 might be an excellent candidate of the Galactic PeVatron and neutrino source.

Keywords: Supernova remnants, Gamma-ray astronomy, Neutrino astronomy, Pulsar wind nebulae
Exploring Nuclear Forces with Pulsar Glitch Observations. We connect nuclear forces to one of the most notable irregular behaviors observed in pulsars, already detected in approximately 6% of known pulsars, with increasingly accurate data expected from upcoming high-precision timing instruments both on the ground and in space. Built on Shang &amp; Li, we conduct a case study on the 2000 glitch of the Vela pulsar. For our purpose, we adopt the relativistic mean field (RMF) model as the theoretical many-body framework to describe nuclear systems. We refit three representative RMF parameter sets (DD-ME2, PKDD, and NL3), considering the uncertainties in nuclear matter saturation properties. Utilizing the resulting star structure, composition, and nucleon properties in the medium obtained in a consistent manner, we calculate the pinning energy of the superfluid vortex in the nuclear lattice in the inner crust. This leads to the evolution of an associated pinning force that acts on the vortex, which can be confronted with the observed glitch amplitude and short time relaxation in the 2000 Vela glitch event, following the snowplow model of the pulsar glitch. We discuss how the vortex configuration and pinning properties depend on the nuclear parameters and find an interesting and dominant role of the nuclear symmetry energy slope in pinning strength.

Keywords: Neutron stars, High energy astrophysics, Pulsars
Solar Cycle Variations in Meridional Flows and Rotational Shear within the Sun's Near-surface Shear Layer. Using solar cycle─long helioseismic measurements of meridional and zonal flows in the near-surface shear layer (NSSL) of the Sun, we study their spatiotemporal variations and connections to active regions. We find that near-surface inflows toward active latitudes are part of a local circulation with an outflow away from them at depths around 0.97 R⊙, which is also the location where the deviations in the radial gradient of rotation change sign. These results, together with opposite signed changes, over latitude and depth, in the above quantities observed during the solar minimum period, point to the action of the Coriolis force on large-scale flows as the primary cause of changes in rotation gradient within the NSSL. We also find that such Coriolis force mediated changes in near-surface flows toward active latitudes only marginally change the amplitude of zonal flow and hence are not likely to be its driving force. Our measurements typically achieve a high signal-to-noise ratio (&gt;5σ) for near-surface flows but can drop to 3σ near the base (0.95 R⊙) of the NSSL. Close agreements between the depth profiles of changes in rotation gradient and in meridional flows measured from quite different global and local helioseismic techniques, respectively, show that the results are not dependent on the analysis techniques.

Keywords: Solar cycle, Solar rotation, Helioseismology, The Sun, Solar meridional circulation, Solar activity
Identifying Thorne–Żytkow Objects through Neutrinos. Thorne–Żytkow objects (T Os) have been predicted to form when a neutron star is engulfed by a diffuse, convective giant envelope. Accretion onto a neutron star at a rate that is larger than 10‑4 M⊙ yr‑1 is expected to lead to significant emission of neutrinos of all flavors with energy of 1–100 MeV. Since the neutrino signal is expected to largely vary in time (from milliseconds to thousands of years), we outline detection strategies tailored to the signal duration. We find that neutrino detection from T Os up to the Small Magellanic Cloud is within the reach of current- and next-generation neutrino observatories, such as Super- and Hyper-Kamiokande, the IceCube Neutrino Observatory, and JUNO. Interestingly, if targeted searches for neutrinos from T O candidates (e.g., VX Sgr in our Galaxy as well as HV 2112 and HV 11417 in the Small Magellanic Cloud) should lead to positive results, neutrinos could positively identify the nature of such sources and their accretion rate. Furthermore, the diffuse supernova neutrino background may be able to rule out extreme scenarios for the formation and accretion rates of TŻOs. Our findings should serve as motivation for establishing dedicated searches for neutrino emission from T Os. This is especially timely since it is challenging to detect TŻOs via electromagnetic radiation unambiguously, and the T O gravitational-wave signal could be probed with next-generation detectors for sources within our Galaxy only.

Keywords: Neutron stars, Accretion, Neutrino telescopes, Neutrino oscillations, Neutrino astronomy, Stellar accretion, Common envelope binary stars
A Disintegrating Rocky Planet with Prominent Comet-like Tails around a Bright Star. We report the discovery of BD+05 4868 Ab, a transiting exoplanet orbiting a bright (V = 10.16) K-dwarf (TIC 466376085) with a period of 1.27 days. Observations from NASA's Transiting Exoplanet Survey Satellite reveal variable transit depths and asymmetric transit profiles that are characteristic of comet-like tails formed by dusty effluents emanating from a disintegrating planet. Unique to BD+05 4868 Ab is the presence of prominent dust tails in both the trailing and leading directions that contribute to the extinction of starlight from the host star. By fitting the observed transit profile and analytically modeling the drift of dust grains within both dust tails, we infer large grain sizes (∼1–10 μm) and a mass-loss rate of 10 M⊕ Gyr‑1, suggestive of a lunar-mass object with a disintegration timescale of only several Myr. The host star is probably older than the Sun and is accompanied by an M-dwarf companion at a projected physical separation of 130 au. The brightness of the host star, combined with the planet's relatively deep transits (0.8%–2.0%), presents BD+05 4868 Ab as a prime target for compositional studies of rocky exoplanets and investigations into the nature of catastrophically evaporating planets.

Keywords: Extrasolar rocky planets, Exoplanets, Exoplanet systems, Planetary geology, Transit photometry
Contribution of Alfvénic Waves on the Formation and Deflection of Switchbacks: Insights from Two Decades of WIND Spacecraft Data. Switchbacks, characterized by large-angle deflections of the local interplanetary magnetic field relative to the background, are frequently observed throughout the heliosphere and play a crucial role in the solar wind dynamics. Recent studies have highlighted the importance of local generation mechanisms, such as expanding waves, turbulence, velocity shear, and footpoint motion, in the formation of switchbacks. Utilizing nearly two decades of data from the WIND spacecraft near 1 au, we conducted a detailed investigation into the differences between switchbacks and their surrounding environment, focusing on the influence of solar wind conditions on their occurrence rate and deflection degree. Our findings indicate that switchbacks are embedded within Alfvén waves, and their occurrence rate and maximum deflection degree are significantly enhanced during large-amplitude Alfvén waves. Specifically, the occurrence rate of switchbacks during these periods shows no significant correlation with solar wind velocity, suggesting that Alfvén wave activity is the primary driver of switchback formation. Our results further indicate that the evolution of switchbacks is closely related to the evolution of Alfvén waves, and that velocity shear and footpoint motion do not play an additional role in their evolution. These findings provide valuable insights into the dynamics of switchbacks and their relationship with solar wind conditions, contributing to a deeper understanding of the complex interactions within the heliosphere.

Keywords: Solar wind, Interplanetary magnetic fields
On the Origin of Long-term Modulation in the Sun's Magnetic Activity Cycle. One of the most striking manifestations of orderly behavior emerging out of complex interactions in any astrophysical system is the 11 yr cycle of sunspots. However, direct sunspot observations and reconstructions of long-term solar activity clearly exhibit amplitude fluctuations beyond the decadal timescale, which may be termed as supradecadal modulation. Whether this long-term modulation in the Sun's magnetic activity results from nonlinear mechanisms or stochastic perturbations remains controversial and a matter of active debate. Utilizing multimillennial-scale kinematic dynamo simulations based on the Babcock–Leighton paradigm—in the likely (near-critical) regime of operation of the solar dynamo—we demonstrate that this supradecadal modulation in solar activity cannot be explained by nonlinear mechanisms alone; stochastic forcing is essential for the manifestation of observed long-term fluctuations in the near-critical dynamo regime. Our findings substantiate some independent observational and theoretical investigations and provide additional insights into temporal dynamics associated with a plethora of natural phenomena in astronomy and planetary systems arising from weakly nonlinear, nondeterministic processes.

Keywords: Solar cycle, Magnetohydrodynamics, Sunspot cycle, Solar dynamo
exoALMA. I. Science Goals, Project Design, and Data Products. Planet formation is a hugely dynamic process requiring the transport, concentration, and assimilation of gas and dust to form the first planetesimals and cores. With access to observations with extremely high spatial and spectral resolution at unprecedented sensitivities, it is now possible to probe the planet-forming environment in detail. To this end, the exoALMA Large Program targeted 15 large protoplanetary disks, ranging between ∼1″ and ∼7″ in radius, and mapped the gas and dust distributions. 12CO J = 3–2, 13CO J = 3–2, and CS J = 7–6 molecular emission was imaged at high angular ( ) and spectral (∼100 m s‑1) resolution, achieving a surface brightness temperature sensitivity of ∼1.5 K over a single channel, while the 330 GHz continuum emission was imaged at 90 mas resolution and achieved a point source sensitivity of ∼40 μJy beam‑1. These observations constitute some of the deepest observations of protoplanetary disks to date. Extensive substructure was found in all but one disk, traced by both dust continuum and molecular line emission. In addition, the molecular emission allowed for the velocity structure of the disks to be mapped with excellent precision (uncertainties of the order of 10 m s‑1), revealing a variety of kinematic perturbations across all sources. From this sample it is clear that, when observed in detail, all disks appear to exhibit physical and dynamical substructure indicative of ongoing dynamical processing due to young, embedded planets, large-scale (magneto)hydrodynamical instabilities or winds.

Keywords: Protoplanetary disks
exoALMA. II. Data Calibration and Imaging Pipeline. The exoALMA Large Program was designed to search for subtle kinematic deviations from Keplerian motion, indicative of embedded planets, in high-angular-resolution and high-spectral-resolution Band 7 observations of 12CO, 13CO, and CS emission from protoplanetary disks. This Letter summarizes the calibration and imaging pipelines used by the exoALMA collaboration. With sources ranging in diameter from   to   when probed by 12CO, multiple antennae configurations were required to maximally recover all spatial information (including Atacama Compact Array data for seven sources). Combining these data sets warranted particular care in their alignment during calibration and prior to imaging so as not to introduce spurious features that might resemble the kinematic deviations being investigated. Phase decoherence was found in several data sets, which was corrected by an iterative self-calibration procedure, and we explored the effects of the order of operations of spatial alignment, flux scaling, and self-calibration. A number of different imaging sets were produced for the continuum and line emission, employing an iterative masking procedure that minimizes bias due to non-Keplerian motions in the disk.

Keywords: Observational astronomy, Calibration, Astronomical techniques, Protoplanetary disks, Radio interferometry
exoALMA. III. Line-intensity Modeling and System Property Extraction from Protoplanetary Disks. The ALMA large program exoALMA offers a unique window into the three-dimensional physical and dynamical properties of 15 circumstellar disks where planets may be actively forming. Here, we present an analysis methodology to map the gas disk structure and substructure encoded in 12CO, 13CO, and CS line emission from our targets. To model and characterize the disk structure probed by optically thin species, such as CS and, in some cases, 13CO, we introduce a composite line profile kernel that accounts for increased intensities caused by the projected overlap between the disk's front and back side emission. Our workflow, built on the DISCMINER modeling framework, incorporates an improved iterative two-component fitting method for inclined sources (i &gt; 40∘) to mitigate the impact of the disk back side on the extraction of velocity maps. Also, we report best-fit parameters for the Keplerian stellar masses, as well as inclinations, position angles, systemic velocities, rotation direction, and emission surfaces of the disks in our sample.

Keywords: Planet formation, Protoplanetary disks, Exoplanets
exoALMA. IV. Substructures, Asymmetries, and the Faint Outer Disk in Continuum Emission. The exoALMA Large Program targeted a sample of 15 disks to study gas dynamics within these systems, and these observations simultaneously produced continuum data at 0.9 mm (331.6 GHz) with exceptional surface brightness sensitivity at high angular resolution. To provide a robust characterization of the observed substructures, we performed a visibility space analysis of the continuum emission from the exoALMA data, characterizing axisymmetric substructures and nonaxisymmetric residuals obtained by subtracting an axisymmetric model from the observed data. We defined a nonaxisymmetry index and found that the most asymmetric disks predominantly show an inner cavity and consistently present higher values of mass accretion rate and near-infrared excess. This suggests a connection between outer disk dust substructures and inner disk properties. The depth of the data allowed us to describe the azimuthally averaged continuum emission in the outer disk, revealing that larger disks (both in dust and gas) in our sample tend to be gradually tapered compared to the sharper outer edge of more compact sources. Additionally, the data quality revealed peculiar features in various sources, such as shadows, inner disk offsets, tentative external substructures, and a possible dust cavity wall.

Keywords: Radio interferometry, Dust continuum emission, Protoplanetary disks, Planet formation
exoALMA. V. Gaseous Emission Surfaces and Temperature Structures. An analysis of the gaseous component in protoplanetary disks can inform us about their thermal and physical structure, chemical composition, and kinematic properties, all of which are crucial for understanding various processes within the disks. By exploiting the asymmetry of the line emission, or via line profile analysis, we can locate the emitting surfaces. Here, we present the emission surfaces of the exoALMA sources in 12CO J = 3─2, 13CO J = 3─2, and CS J = 7─6. We find that 12CO traces the upper disk atmosphere, with mean &lt;z/r&gt; values of ≍0.28, while 13CO and CS trace lower regions of the disk with mean &lt;z/r&gt; values of ≍0.16 and ≍0.18, respectively. We find that 12CO &lt;z/r&gt; and the disk mass are positively correlated with each other; this relationship offers a straightforward way to infer the disk mass. We derive 2D r ─ z temperature distributions of the disks. Additionally, we search for substructure in the surfaces and radial intensity profiles; we find evidence of localized substructure in the emission surfaces and peak intensity profiles of nearly every disk, with this substructure often being coincident between molecular tracers, intensity profiles, and kinematic perturbations. Four disks display evidence of potential photodesorption, implying that this effect may be common even in low far-ultraviolet star-forming regions. For most disks, we find that the physical and thermal structure is more complex than analytical models can account for, highlighting a need for more theoretical work and a better understanding of the role of projection effects on our observations.

Keywords: High angular resolution, Protoplanetary disks, Planet formation, CO line emission
exoALMA. VI. Rotating under Pressure: Rotation Curves, Azimuthal Velocity Substructures, and Gas Pressure Variations. The bulk motion of the gas in protoplanetary disks around newborn stars is nearly Keplerian. By leveraging the high angular and spectral resolution of the Atacama Large Millimeter/submillimeter Array (ALMA), we can detect small-scale velocity perturbations in molecular line observations caused by local gas pressure variations in the disk, possibly induced by embedded protoplanets. This Letter presents the azimuthally averaged rotational velocity and its deviations from Keplerian rotation (δυϕ) for the exoALMA sample, as measured in the 12CO J = 3–2 and 13CO J = 3–2 emission lines. The rotation signatures show evidence for vertically stratified disks, in which 13CO rotates faster than 12CO due to a distinct thermal gas pressure gradient at their emitting heights. We find δυϕ substructures in the sample on both small (∼10 au) and large (∼100 au) radial scales, reaching deviations up to 15% from background Keplerian velocity in the most extreme cases. More than 75% of the rings and 80% of the gaps in the dust continuum emission resolved in δυϕ are colocated with gas pressure maxima and minima, respectively. Additionally, gas pressure substructures are observed far beyond the dust continuum emission. For the first time, we determined the gas pressure derivative at the midplane from observations, and found it to align well with the dust substructures within the given uncertainties. Based on our findings, we conclude that gas pressure variations are likely the dominant mechanism for ring and gap formation in the dust continuum.

Keywords: Planetary system formation, Planetary-disk interactions, Protoplanetary disks, Planet formation