Sazuna/UAT_keywords huggingface dataset:
Detection of Enhanced Germanium in a New Cool Extreme Helium Star A980: Insights and Implications. A fine abundance analysis of a recently discovered hydrogen-deficient carbon (HdC) star, A980, is presented. Based on the observed high-resolution optical spectrum, we ascertain that A980 is a cool extreme helium (EHe) star and not an HdC star. Singly ionized germanium Ge II lines are identified in A980's optical spectrum. These are the first-ever detections of germanium lines in an EHe star's observed spectrum and provide the first measurements of germanium abundance in an EHe star. The overabundance of germanium in A980's atmosphere provides us with evidence for the synthesis of germanium in EHe stars. Among the known cool EHe stars, A980 exhibits a maximum enhancement of the s-process elements based on a significant number of transitions. The measured elemental abundances reveal signs of H-burning, He-burning, and specifically the nucleosyntheses of the key elements Ge, Sr, Y, Zr, and Ba. The nucleosyntheses of these key elements are discussed in light of asymptotic giant branch evolution and the expectation from the accretion of an He white dwarf by a C–O white dwarf or by a neutron star.

Keywords: Nucleosynthesis, Helium-rich stars, Chemical abundances, Hydrogen deficient stars, Chemically peculiar stars
HCG 57: Evidence for Shock-heated Intergalactic Gas from X-Rays and Optical Emission Line Spectroscopy. We present Chandra and XMM-Newton X-ray observations of the compact group HCG 57, and optical integral field spectroscopy of the interacting galaxy pair HCG 57A/D. These two spiral galaxies recently suffered an off-axis collision with HCG 57D passing through the disk of A. We find evidence of a gas bridge linking the galaxies, containing ∼108M⊙ of hot, ∼1 keV thermal plasma and warm ionized gas radiating in Hα, Hβ, [O III] and [N II] lines. The optical emission lines in the central regions of HCG 57D show excitation properties consistent with H II-regions, while the outer rim of HCG 57D parts of the bridge and the outer regions of HCG 57A show evidence of shocked gas consistent with shock velocities of 200–300 km s‑1. In contrast, the X-ray emitting gas requires a collision velocity of 650–750 km s‑1 to explain the observed temperatures. These different shock velocities can be reconciled by considering the contributions of rotation to collision velocity in different parts of the disks, and the clumpy nature of the preshock medium in the galaxies, which likely lead to different shock velocities in different components of the turbulent postshocked gas. We examine the diffuse X-ray emission in the group members and their associated point sources, identifying X-ray active galactic nuclei in HCG 57A, B, and D. We also confirm the previously reported ∼1 keV intra-group medium and find it to be relaxed with a low central entropy (18.0 ± 1.7 keV cm2 within 20 kpc) but a long cooling time (5.9 ± 0.8 Gyr).

Keywords: Hickson compact group, Galaxy groups, Galaxy collisions, Galaxy interactions
A Dichotomy in the 1–24 GHz Parsec-scale Radio Spectra of Radio-quiet Quasars. We present the parsec-scale radio spectra of a representative sample of 13 Palomar–Green radio-quiet quasars, based on our new Very Long Baseline Array (VLBA) observations at 8.4 and 23.6 GHz and our earlier VLBA studies at 1.5 and 5.0 GHz. The radio core emission generally exhibits a flat spectrum at 1.5–5.0 GHz, which indicates a compact optically thick synchrotron source on a scale smaller than the broad-line region (BLR) radius RBLR ∼ 0.01–0.1 pc. The 8.4–23.6 GHz spectral slope remains flat in four objects indicating the inner radius of the radio source Rin &lt; 0.1RBLR, and becomes steep in four other objects indicating Rin ∼ 0.5 RBLR. The flat 8.4–23.6 GHz slope sources may be associated with a continuous ejection starting at the accretion disk corona. The steep 8.4–23.6 GHz slope sources may be produced by an interaction of an active-galactic-nucleus-driven wind with the BLR gas or a low-power jet extending to the BLR scale. Seven of these eight objects, which have a flat or steep 8.4–23.6 GHz slope, reside at the Eddington ratios L/LEdd &lt; 0.3, and four of the remaining five objects, where the 8.4–23.6 GHz fluxes are too faint to significantly constrain the slope, reside at L/LEdd &gt; 0.3. The 8.4–23.6 GHz radio emission in the high-L/LEdd objects may be weak due to more extended emission from a radiation-pressure-driven wind. Future submillimeter observations can further constrain the inward radial extent of the radio emission down to the coronal scale.

Keywords: Radio continuum emission, Radio quiet quasars, Active galactic nuclei
Unraveling the Dusty Environment around RT Vir. Infrared (IR) studies of asymptotic giant branch (AGB) stars are critical to our understanding of the formation of cosmic dust. In this investigation, we explore the mid- to far-IR emission of the oxygen-rich AGB star RT Virginis. This optically thin dusty environment has unusual spectral features when compared to other stars in its class. To explore this enigmatic object we use the one-dimensional radiative transfer modeling code DUSTY. Modeled spectra are compared with observations from the Infrared Space Observatory, InfraRed Astronomical Satellite, the Herschel Space Observatory, and a host of other sources to determine the properties of RT Vir's circumstellar material. Our models suggest a set of two distant and cool dust shells at low optical depths (τV,inner = 0.16, τV,outer = 0.06), with inner dust temperatures T1 = 330 K, T3 = 94 K. Overall, these dust shells exhibit a chemical composition consistent with dust typically found around O-rich AGB stars. However, the distribution of materials differs significantly. The inner shell consists of a mixture of silicates, Al2O3, FeO, and Fe, while the outer shell primarily contains crystalline Al2O3 polymorphs. This chemical change is indicative of two distinct epochs of dust formation around RT Vir. These changes in dust composition are driven by either changes in the pressure–temperature conditions around the star or by a decrease in the C/O ratio due to hot-bottom burning.

Keywords: Radiative transfer simulations, Dust formation, Infrared astronomy, Asymptotic giant branch stars, Dust shells, Circumstellar dust
Jupiter Evolutionary Models Incorporating Stably Stratified Regions. We address the issue of which broad set of initial conditions for the planet Jupiter best matches the current presence of a "fuzzy core" of heavy elements, while at the same time comporting with measured parameters such as its effective temperature, atmospheric helium abundance, radius, and atmospheric metallicity. Our focus is on the class of fuzzy cores that can survive convective mixing to the present day and on the unique challenges of an inhomogeneous Jupiter with stably stratified regions now demanded by the Juno gravity data. Hence, using the new code APPLE, we attempt to put a nonadiabatic Jupiter into an evolutionary context. This requires not only a mass density model, the major relevant byproduct of the Juno data, but a thermal model that is subject to interior heat transport, a realistic atmospheric flux boundary, a helium rain algorithm, and the latest equation of state. The result is a good fit to most major thermal, compositional, and structural constraints that still preserve a fuzzy core and that should inform future more detailed models of the current Jupiter in the context of its evolution from birth.

Keywords: Solar system gas giant planets, Planetary science, Planetary cores, Planetary interior, Extrasolar gaseous giant planets, Planetary structure
Vortex-induced Rings and Gaps within Protoplanetary Disks. Observations of protoplanetary disks have revealed the presence of both crescent-shaped and ring-like structures in dust continuum emission. These crescents are thought to arise from dust-trapping vortices generated by the Rossby wave instability, which induces density waves akin to those caused by planets. These vortices have the potential to create gaps and rings within the disk, resulting from the dissipation of their density waves. We carry out 2D hydrodynamic simulations in the shearing box to investigate vortex–disk interaction. We find that long-lived vortices can produce dust rings and gaps in inviscid discs detectable by the Atacama Large Millimeter/submillimeter Array, and a more elongated vortex produces rings at larger separations. Vortex-induced density waves carry over 2 orders of magnitude higher angular momentum flux compared to planet-induced ones that shock at the same location, making the former much more effective at producing dust gaps and rings far away.

Keywords: Protoplanetary disks, Planet formation
A Semi-analytical Model for Stellar Evolution in AGN Disks. Disks of gas accreting onto supermassive black holes may host numerous stellar-mass objects, formed within the disk or captured from a nuclear star cluster. We present a simplified model of stellar evolution in these dense environments, which exhibits exceptional agreement with full stellar evolution calculations at a minuscule fraction of the cost. Although the model presented here is limited to stars burning hydrogen in their cores, it is sufficient to determine the evolutionary fate of disk-embedded stars: whether they proceed to later stages of nuclear burning and leave behind a compact remnant, reach a quasi-steady state where mass loss and accretion balance one another, or whether accretion proceeds faster than stellar structure can adjust, causing a runaway. We highlight how various disk parameters and phenomena such as gap opening affect stellar evolution outcomes. We also highlight how our model can accommodate time-varying conditions, such as those experienced by a star on an eccentric orbit, and can couple to N-body integrations. This model will enable more detailed studies of stellar populations and their interaction with accretion disks than have previously been possible.

Keywords: Galactic center, Quasars, Massive stars, Stellar evolutionary models, Stellar physics
Fast-rotating A- and F-type Stars with Hα Emissions in NGC 3532: Candidate UV-dim Stars?. Extended main-sequence stars that are dim in the ultraviolet passbands of the Hubble Space Telescope (UV-dim stars) are found in several young and intermediate-age star clusters in the Magellanic Clouds (MCs). The obscuring of the dust in the disks of stars expelled as a result of fast rotation has been suggested to be responsible for the appearance of UV-dim stars and to play an important role in the formation of extended main sequences. In this paper, we report a population of A- and F-type stars that show Hα emission features in their spectra in the young (~340 Myr old) neighboring Galactic star cluster NGC 3532. By fitting the observed absorption profiles, we found that most Hα emitters are fast-rotating stars, indicating that they form decretion disks by fast rotation like Be stars. As A- and F-type stars dominate the extended main-sequence turnoff regions of intermediate-age clusters, their appearance provides observational evidence to support the dust extinction scenario for these clusters, and they might be the counterparts of UV-dim stars that are detected in remote MC star clusters such as NGC 1783.

Keywords: Early-type stars, Stellar rotation, Open star clusters
Spectroscopic Confirmation of a Massive Protocluster with Two Substructures at z ≃ 3.1. We present the results of a Keck and Northern Extended Millimeter Array spectroscopic survey of 507 galaxies, where we confirm the presence of two massive overdensities at z = 3.090‑3.110 and z = 3.133‑3.155 in the neighborhood of the GOODS-N, each with over a dozen spectroscopically confirmed members. We find that both of these have galaxy overdensities of near-infrared-detected galaxies of δgal,obs = 6‑9 within corrected volumes of (6‑7) × 103 cMpc3. We estimate the properties of the z = 0 descendants of these overdensities using a spherical collapse model and find that both should virialize by z ≃ 0.5‑0.8, with total masses of Mtot ≃ (6‑7) × 1014 M⊙. The same spherical collapse calculations, as well as a clustering-of-clusters statistical analysis, suggest a &gt;80% likelihood that the two overdensities will collapse into a single cluster with Mtot = (1.0‑1.5) × 1015 M⊙ by z ~ 0.1‑0.4. The z = 3.14 substructure contains a core of four bright dusty star-forming galaxies with ΣSFR = 2700 ± 700M⊙ yr‑1 in a volume of only 280 cMpc3.

Keywords: Redshift surveys, Galaxy evolution, High-redshift galaxy clusters
H-AMR FORGE'd in FIRE. I. Magnetic State Transitions, Jet Launching, and Radiative Emission in Super-Eddington, Highly Magnetized Quasar Disks Formed from Cosmological Initial Conditions. Quasars are powered by supermassive black hole (SMBH) accretion disks, yet standard thin disk models are inconsistent with many observations. Recently, P. F. Hopkins et al. simulated the formation of a quasar disk feeding an SMBH of mass M = 1.3 × 107 M⊙ in a galaxy. The disk had surprisingly strong toroidal magnetic fields that supported it vertically from gravity and powered rapid accretion. What feedback can such a system produce? To answer this, we must follow the gas to the event horizon. For this, we interpolated the quasar into the general-relativistic radiation magnetohydrodynamics code H-AMR and performed 3D simulations with BH spins a = 0 and a = 0.9375. This remapping generates magnetic monopoles, which we erase using a novel divergence cleaning approach. Despite the toroidal magnetic field's dominance at large radii, vertical magnetic flux builds up near the event horizon, leading to a magnetic state transition within the inner 200 gravitational radii of the disk. This powers strong winds and, for spinning BHs, relativistic jets that can spin down the BH within 5‑10 Myr. Sometimes, vertical magnetic fields of opposite polarity reach the BH, causing a polarity inversion event that briefly destroys the jets and, possibly, the X-ray corona. These strong fields power accretion at rates 5× the Eddington limit, which can double the BH mass in 5–10 Myr. When a = 0.9375 (a = 0), the energy in mechanical outflows and radiation equals about 60% (10%) and 100% (3%) of the accreted rest mass energy, respectively. Much of the light escapes in cool, ≳1300 au photospheres, consistent with quasar microlensing and spectral energy distributions.

Keywords: Galaxy accretion disks, Relativistic jets, Active galactic nuclei, General relativity, Magnetohydrodynamical simulations
Carbon and Iron Deficiencies in Quiescent Galaxies at z = 1–3 from JWST-SUSPENSE: Implications for the Formation Histories of Massive Galaxies. We present the stellar metallicities and multielement abundances (C, Mg, Si, Ca, Ti, Cr, and Fe) of 15 massive (log M/M⊙ = 10.2–11.2) quiescent galaxies at z = 1–3, derived from ultradeep JWST-SUSPENSE spectra. Compared to quiescent galaxies at z ∼ 0, these galaxies exhibit a deficiency of 0.26 ± 0.04 dex in [C/H], 0.16 ± 0.03 dex in [Fe/H], and 0.07 ± 0.04 dex in [Mg/H], implying rapid formation and quenching before significant enrichment from asymptotic giant branch stars and Type Ia supernovae. Additionally, we find that galaxies forming at higher redshift consistently show higher [Mg/Fe] and lower [Fe/H] and [Mg/H], regardless of their observed redshift. The evolution in [Fe/H] and [C/H] is therefore primarily driven by lower-redshift samples naturally including galaxies with longer star formation timescales. In contrast, the lower [Mg/H] likely reflects earlier-forming galaxies expelling larger gas reservoirs during their quenching phase. Consequently, the mass–metallicity relation, primarily reflecting [Mg/H], is somewhat lower at z = 1–3 compared to the lower-redshift relation. Finally, we compare our results to standard stellar population modeling approaches employing solar abundance patterns and nonparametric star formation histories (using PROSPECTOR). Our simple stellar population (SSP)-equivalent ages agree with the mass-weighted ages from PROSPECTOR, while the metallicities disagree significantly. Nonetheless, the metallicities better reflect [Fe/H] than total [Z/H]. We also find that the star formation timescales inferred from elemental abundances are significantly shorter than those from PROSPECTOR, and we discuss the resulting implications for the early formation of massive galaxies.

Keywords: Galaxy quenching, Galaxy formation, Metallicity, Chemical abundances
The JADES Transient Survey: Discovery and Classification of Supernovae in the JADES Deep Field. The JWST Advanced Deep Extragalactic Survey (JADES) is a multicycle JWST program that has taken among the deepest near- and mid-infrared images to date (down to ∼30 AB mag) over ∼25 arcmin2 in the GOODS-S field in two sets of observations with 1 yr of separation. This presented the first opportunity to systematically search for transients, mostly supernovae (SNe), out to z &gt; 2. We found 79 SNe: 38 at z &lt; 2, 23 at 2 &lt; z &lt; 3, 8 at 3 &lt; z &lt; 4, 7 at 4 &lt; z &lt; 5, and 3 with undetermined redshifts, where the redshifts are predominantly based on spectroscopic or highly reliable JADES photometric redshifts of the host galaxies. At this depth, the detection rate is ∼1–2 arcmin–2 yr–1, demonstrating the power of JWST as an SN discovery machine. We also conducted multiband follow-up NIRCam observations of a subset of the SNe to better constrain their light curves and classify their types. Here, we present the survey, sample, search parameters, spectral energy distributions, light curves, and classifications. Even at z ≥ 2, the NIRCam data quality is high enough to allow SN classification via multiepoch light-curve fitting with confidence. The multiepoch SN sample includes a Type Ia SN at z spec = 2.90, a Type IIP SN at z spec = 3.61, and a Type Ic-BL SN at z spec = 2.83. We also found that two z ∼ 16 galaxy candidates from the first imaging epoch were actually transients that faded in the second epoch, illustrating the possibility that moderate/high-redshift SNe could mimic high-redshift dropout galaxies.

Keywords: Supernovae
The Blue Lurker WOCS 14020: A Long-period Post-common-envelope Binary in M67 Originating from a Merger in a Triple System. We present Hubble Space Telescope far-ultraviolet (FUV) spectra of a blue lurker–white dwarf (BL–WD) binary system in the 4 Gyr open cluster M67. We fit the FUV spectrum of the WD, determining it is a C/O WD with a mass of   M⊙ and a cooling age of ~400 Myr. This requires a WD progenitor of ~3 M⊙, significantly larger than the current cluster turnoff mass of 1.3 M⊙. We suggest the WD progenitor star formed several hundred megayears ago via the merger of two stars near the turnoff of the cluster. In this scenario, the original progenitor system was a hierarchical triple consisting of a close, near-equal-mass inner binary, with a tertiary companion with an orbit of a few thousand days. The WD is descended from the merged inner binary, and the original tertiary is now the observed BL. The likely formation scenario involves a common envelope while the WD progenitor is on the AGB, and thus the observed orbital period of 359 days requires an efficient common envelope ejection. The rapid rotation of the BL indicates it accreted some material during its evolution, perhaps via a wind prior to the common envelope. This system will likely undergo a second common envelope in the future and thus could result in a short-period double WD binary or merger of a 0.72 M⊙ C/O WD and a 0.38 M⊙ helium WD, making this a potential progenitor of an interesting transient such as a sub-Chandrasekhar Type Ia supernova.

Keywords: Binary stars, Multiple star evolution, White dwarf stars, Stellar evolution, Roche lobe overflow, Type Ia supernovae, Open star clusters, Trinary stars, Blue straggler stars, Common envelope evolution, Common envelope binary stars
Late-time Radio Brightening and Emergence of a Radio Jet in the Changing-look AGN 1ES 1927+654. We present multifrequency (5–345 GHz) and multiresolution radio observations of 1ES 1927+654, widely considered one of the most unusual and extreme changing-look active galactic nuclei (CL-AGNs). The source was first designated a CL-AGN after an optical outburst in late 2017 and has since displayed considerable changes in X-ray emission, including the destruction and rebuilding of the X-ray corona in 2019–2020. Radio observations prior to 2023 show a faint and compact radio source typical of a radio-quiet AGN. Starting in 2023 February, 1ES 1927+654 began exhibiting a radio flare with a steep exponential rise, reaching a peak 60 times previous flux levels, and has maintained this higher level of radio emission for over a year to date. The 5–23 GHz spectrum is broadly similar to gigahertz-peaked radio sources, which are understood to be young radio jets less than ∼1000 yr old. Recent high-resolution Very Long Baseline Array observations at 23.5 GHz now show resolved extensions on either side of the core, with a separation of ∼0.15 pc, consistent with a new and mildly relativistic bipolar outflow. A steady increase in the soft X-ray band (0.3–2 keV) concurrent with the radio may be consistent with jet-driven shocked gas, though further observations are needed to test alternate scenarios. This source joins a growing number of CL-AGNs and tidal disruption events that show late-time radio activity, years after the initial outburst.

Keywords: Radio jets, Seyfert galaxies, X-ray active galactic nuclei, Active galactic nuclei, Proper motions, Radio active galactic nuclei
Dynamic Imprints of Colliding-wind Dust Formation from WR 140. Carbon-rich Wolf–Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The "textbook" example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among the first to utilize two separate JWST observations, from Cycle 1 ERS (2022 July) and Cycle 2 (2023 September), to measure WR 140's dust kinematics and confirm its morphology. To measure the proper motions and projected velocities of the dust shells, we performed a novel point-spread function (PSF) subtraction to reduce the effects of the bright diffraction spikes and carefully aligned the Cycle 2 to the Cycle 1 images. At 7.7 μm, through the bright feature common to 16 dust shells (C1), we find an average dust shell proper motion of 390 ± 29 mas yr‑1, which equates to a projected velocity of 2714 ± 188 km s‑1 at a distance of 1.64 kpc. Our measured speeds are constant across all visible shells and consistent with previously reported dust expansion velocities. Our observations not only prove that these dusty shells are astrophysical (i.e., not associated with any PSF artifact) and originate from WR 140, but also confirm the "clumpy" morphology of the dust shells, in which identifiable substructures within certain shells persist for at least 14 months from one cycle to the next. These results support the hypothesis that clumping in the wind collision region is required for dust production in WR binaries.

Keywords: Wolf-Rayet stars, Binary stars, Dust formation