Sazuna/UAT_keywords huggingface dataset:
Global Turbulent Solar Convection: A Numerical Path Investigating Key Force Balances in the Context of the Convective Conundrum. Understanding solar turbulent convection and its influence on differential rotation has been a challenge over the past two decades. Current models often overestimate giant convection cells' amplitude, leading to an effective Rossby number (Ro) too large and a shift toward an antisolar rotation regime. This convective conundrum underscores the need for improved comprehension of solar convective dynamics. We propose a numerical experiment in the parameter space that controls Ro while increasing the Reynolds number (Re) and maintaining solar parameters. By controlling the Nusselt number (Nu), we limit the energy transport by convection while reducing viscous dissipation. This approach enabled us to construct a Sun-like rotating model (SBR97n035) with strong turbulence (Re ∼ 800) that exhibits prograde equatorial rotation and aligns with observational data from helioseismology. We compare this model with an antisolar rotating counterpart and provide an in-depth spectral analysis to investigate the changes in convective dynamics. We also find the appearance of vorticity rings near the poles, whose existence on the Sun could be probed in the future. The Sun-like model shows reduced buoyancy over the spectrum, as well as an extended quasi-geostrophic equilibrium toward smaller scales. This promotes a Coriolis─inertia (CI) balance rather than a Coriolis─inertia─Archimedes (CIA) balance, in order to favor the establishment of a prograde equator. The presence of convective columns in the bulk of the convection zone, with limited surface manifestations, also hints at such structures potentially occurring in the Sun.

Keywords: Hydrodynamical simulations, Stellar convective zones, Solar analogs, Solar differential rotation, Hydrodynamics, The Sun, Astrophysical fluid dynamics
The Young Ages of 70 μm Dark Clumps Inferred from Carbon Chain Chemistry. The physical conditions of the earliest environment of high-mass star formation are currently poorly understood. To that end, we present observations of the carbon chain molecules HC5N, CCS, and HC7N in the 22─25 GHz band toward 12 high-mass 70 μm dark clumps (SMDC) with the Karl G. Jansky Very Large Array. We detect HC5N and CCS toward 11 of these SMDC sources. We calculate column densities and abundances relative to H2 for HC5N and CCS. We do not find any clear HC7N detections in the 11 sources individually, but by stacking the HC7N spectra, we do detect HC7N on average in these sources. We also calculate the ratio of the column densities of HC5N to HC7N using the stacked spectra of both species. We compare our measured abundances of HC5N and our measured ratio of HC5N to HC7N to the UMIST dark cloud chemistry models to constrain an age for the gas assuming a fixed volume density and temperature. The chemical models favor a chemical evolutionary age &lt;1 Myr at densities of n(H2) ≍ 2 × 104 cm−3. The consistent carbon-chain detections and young model-derived ages support the conclusion that these 11 70 μm dark clumps lack high-mass protostars because they are young and not because they are inefficient and incapable of high-mass star formation.

Keywords: Interstellar molecules, Star formation, Dark interstellar clouds, Infrared dark clouds
Looking at the Distant Universe with the MeerKAT Array: The H I Mass Function in the Local Universe. We present measurements of the neutral atomic hydrogen (H I) mass function (HIMF) and cosmic H I density (ΩH I) at 0 ≤ z ≤ 0.088 from the Looking at the Distant Universe with MeerKAT Array (LADUMA) survey. Using LADUMA Data Release 1 (DR1), we analyze the HIMF via a new "recovery matrix" method that we benchmark against a more traditional modified maximum likelihood (MML) method. Our analysis, which implements a forward modeling approach, corrects for survey incompleteness and uses extensive synthetic source injections to ensure robust estimates of the HIMF parameters and their associated uncertainties. This new method tracks the recovery of sources in mass bins different from those in which they were injected and incorporates a Poisson likelihood in the forward modeling process, allowing it to correctly handle uncertainties in bins with few or no detections. The application of our analysis to a high-purity subsample of the LADUMA DR1 spectral line catalog in turn mitigates any possible biases that could result from the inconsistent treatment of synthetic and real sources. For the surveyed redshift range, the recovered Schechter function normalization, low-mass slope, and "knee" mass are   Mpc‑3 dex‑1,  , and  , respectively, which together imply a comoving cosmic H I density of  . Our results show consistency between recovery matrix and MML methods and with previous low-redshift studies, giving confidence that the cosmic volume probed by LADUMA, even at low redshifts, is not an outlier in terms of its H I content.

Keywords: Galaxy masses, Galaxies, H I line emission
The Unexpected Lack of Asymmetry in the Horizon-scale Image of Sagittarius A*. The ring-like images of the two supermassive black holes captured by the Event Horizon Telescope (EHT) provide powerful probes of the physics of accretion flows at horizon scales. Specifically, the brightness asymmetry in the images carries information about the angular velocity profile of the inner accretion flow and the inclination of the observer, owing to the Doppler boosts photons experience at their site of emission. In this paper, we develop a method for quantifying the brightness asymmetry of black hole images in the Fourier domain, which can be measured directly from interferometric data. We apply this method to current EHT data and find that the image of Sagittarius A* (Sgr A*) has an unusually low degree of asymmetry that is even lower than that inferred for M87. We then use a covariant semianalytic model to obtain constraints on the inclinations and velocity profiles of the inner accretion flow for Sgr A*. We find that the lack of significant brightness asymmetry forces the observer inclination to uncomfortably small values (6°–10∘), if the plasma velocity follows Keplerian profiles. Alternatively, larger inclination angles can be accommodated if the plasma velocities are significantly sub-Keplerian and the black hole is not spinning rapidly.

Keywords: Accretion, Supermassive black holes, Plasma astrophysics
The S-PLUS 12-band Photometry as a Powerful Tool for Discovery and Classification: Ten Cataclysmic Variables in a Proof-of-concept Study. Multiband photometric surveys provide a straightforward way to discover and classify astrophysical objects systematically, enabling the study of a large number of targets at relatively low cost. Here we introduce an alternative approach to select accreting white dwarf (AWD) candidates following their spectral energy distribution, entirely supported by the twelve photometric bands of the Southern Photometric Local Universe Survey (S-PLUS). The method was validated with optical spectroscopic follow-up with the Gemini South telescope, which unambiguously established ten systems as cataclysmic variables (CVs), alongside Swift X-ray observations of four of them. Among the ten CVs presented here are those that may be low-luminosity intermediate polars or WZ Sge-type dwarf novae with rare outbursts, two subclasses that can be easily missed in time-domain and X-ray surveys, the two methods currently dominating the discovery of new CVs. Our approach based on S-PLUS provides an important complementary tool to uncover the total population of CVs and the complete set of its subclasses, which is an important step toward a full understanding of close binary evolution, including the origin of magnetic fields in white dwarfs and the physics of accretion. Finally, we highlight the potential of S-PLUS beyond AWDs, serving other surveys in the characterization of their sources.

Keywords: Cataclysmic variable stars
Petrogenesis of Chang'e-6 Basalts and Implication for the Young Volcanism on the Lunar Farside. Mare basalts from lunar farside are pivotal for unraveling lunar nearside-farside dichotomies and global thermal history. The Chang'e-6 (CE-6) mission conducted the first sampling from a young basaltic unit within the Apollo basin on the lunar farside. Here, we performed comprehensive petrological and geochemical analyses on the CE-6 basalt clasts. The CE-6 basalt is a low-titanium basalt (about 5 wt% TiO2) depleted in KREEP components. The absence of olivine, particularly magnesium-rich olivine, suggests that the basaltic magma underwent extensive fractional crystallization. Thermodynamic modeling supports that there may be 10%–20% late-stage cumulates of magma ocean (clinopyroxene and ilmenite) present in the source region of CE-6 basalt. The magma derived from the partial melting of such lunar mantle may undergo fractional crystallization dominated by olivine and clinopyroxene within a shallow magma cg1hamber, followed by eruption. Modeling of the REE pattern further indicates that 3%–7% batch melting of a depleted lunar mantle source, combined with 21%–59% fractional crystallization, achieves the observed REE abundances of CE-6 basalt. The genesis of CE-6 basalt could be attributed to the synergistic influence of a readily fusible mantle source, resulting from the incorporation of late-stage cumulates, and the crust-mantle deformation induced by large impacts. This could serve as a paradigm for the formation of other young basalts on the Moon.

Keywords: Lunar petrology, The Moon, Lunar mineralogy, Lunar science
Thirty-five Years of Timing of M53A with Arecibo and FAST. PSR B1310+18A is a 33 ms binary pulsar in a 256 day, low eccentricity orbit with a low-mass companion located in NGC 5024 (M53). In this Letter, we present the first phase-coherent timing solution for this pulsar (designated as M53A) derived from a 35 yr timing baseline; this combines the archival Arecibo Observatory data with the recent observations from the Five-hundred-meter Aperture Spherical radio Telescope. We find that the spin period derivative of the pulsar is between 6.1 and 7.5 × 10‑19 s s‑1, which implies a characteristic age between 0.70 and 0.85 Gyr. The timing solution also includes a precise position and proper motion for the pulsar, enabling the identification of the companion of M53A in Hubble Space Telescope data as a helium white dwarf (He WD) with a mass of   and a cooling age of  , confirming that the system formed recently in the history of the globular cluster. The system resembles, in its spin and orbital characteristics, similarly wide pulsar–He WD systems in the Galactic disk. We conclude by discussing the origin of slow pulsars in globular clusters, showing that none of the slow pulsars in low-density globular clusters are as young as the systems observed in the densest known globular clusters.

Keywords: Globular star clusters, Radio telescopes, Binary pulsars, Millisecond pulsars
The Ophiuchus DIsk Survey Employing ALMA (ODISEA): Complete Size Distributions for the 100 Brightest Disks across Multiplicity and Spectral Energy Distribution Classes. The size of a protoplanetary disk is a fundamental property, yet most remain unresolved, even in nearby star-forming regions (d ∼ 140–200 pc). We present the complete continuum size distribution for the 105 brightest protoplanetary disks (Mdust ≳ 2 M⊕) in the Ophiuchus cloud, obtained from ALMA Band 8 (410 GHz) observations at 0 05 (7 au) to 0 15 (21 au) resolution. This sample includes 54 Class II and 51 Class I and flat-spectrum sources, providing a comprehensive distribution across evolutionary stages. We measure the half-width at half-maximum and the radius encircling 68% of the flux (R68%) for most nonbinary disks, yielding the largest flux-limited sample of resolved disks in any star-forming region. The distribution is log-normal with a median value of ∼14 au and a logarithmic standard deviation   (factor of 2.9 in linear scale). Disks in close-binary systems (&lt;200 au separation) have smaller radii, with a median value of ∼5 au, indicating efficient radial drift as predicted by dust evolution models. The size distribution for young embedded objects (spectral energy distribution Class I and flat spectrum, age ≲1 Myr) is similar to that of Class II objects (age ∼ a few Myr), implying that pressure bumps must be common at early disk stages to prevent millimeter-sized particle migration at astronomical unit scales.

Keywords: Planetary system formation, Submillimeter astronomy, Pre-main sequence stars, Protoplanetary disks
Subtle and Spectacular: Diverse White Dwarf Debris Disks Revealed by JWST. This Letter reports 12 novel spectroscopic detections of warm circumstellar dust orbiting polluted white dwarfs using the JWST Mid-Infrared Instrument (MIRI). The disks span 2 orders of magnitude in fractional infrared brightness and more than double the number of white dwarf dust spectra available for mineralogical study. Among the highlights are (i) the two most subtle infrared excesses yet detected, (ii) the strongest silicate emission features known for any debris disk orbiting any main-sequence or white dwarf star, (iii) one disk with a thermal continuum but no silicate emission, and (iv) three sources with likely spectral signatures of silica glass. The near ubiquity of solid-state emission requires small dust grains that are optically thin and thus must be replenished on year-to-decade timescales by ongoing collisions. The disk exhibiting a featureless continuum can only be fit by dust temperatures in excess of 2000 K, implying highly refractory material comprised of large particles, or non-silicate mineral species. If confirmed, the glassy silica orbiting three stars could be indicative of high-temperature processes and subsequent rapid cooling, such as occur in high-velocity impacts or vulcanism. These detections have been enabled by the unprecedented sensitivity of MIRI low-resolution spectrometer spectroscopy and highlight the capability and potential for further observations in future cycles.

Keywords: Extrasolar rocky planets, White dwarf stars, Planetary mineralogy, Chemical abundances, Infrared excess, Planetesimals, Debris disks
Dominant Role of Coplanar Inflows in Driving Disk Evolution Revealed by Gas-phase Metallicity Gradients. Using spatially resolved spectroscopic data from the Mapping Nearby Galaxies at Apache Point Observatory sample, we investigate the parameters influencing the radial gradients of gas-phase metallicity ( ) to determine whether disk formation is primarily driven by coplanar gas inflow or by the independent evolution of distinct regions within the disk. Our results show that   strongly correlates with local gas-phase metallicity at a given stellar mass, with steeper gradients observed in metal-poorer disks. This trend supports the coplanar gas inflow scenario, wherein the gas is progressively enriched by in situ star formation as it flows inward. In contrast, the radial gradient of stellar mass surface density shows very weak correlations with  , which is inconsistent with the independent evolution mode, where gas inflow, star formation, and metal enrichment occur independently within each annulus of the disk. Furthermore, we find that   is also closely correlated with an indicator of local gas turbulence  , highlighting the competing roles of turbulence and coplanar inflow in shaping metallicity gradients. Our results provide indirect observational evidence supporting coplanar gas inflow as the driving mechanism for disk evolution.

Keywords: Star formation, Galaxy evolution, Disk galaxies
A Long Spin Period for a Sub-Neptune-mass Exoplanet. HIP 41378 f is a sub-Neptune exoplanet with an anomalously low density. Its long orbital period and deep transit make it an ideal candidate for detecting oblateness photometrically. We present a new cross-platform, GPU-enabled code, greenlantern, suitable for computing transit light curves of oblate planets at arbitrary orientations. We then use the Markov Chain Monte Carlo method to fit K2 data of HIP 41378 f, specifically examining its transit for evidence of oblateness and obliquity. We find that the flattening of HIP 41378 f is f ≤ 0.889 at the 95% confidence level, consistent with a rotation period of Prot ≥ 15.3 hr. In the future, high-precision data from JWST have the potential to tighten such a constraint and can differentiate between spherical and flattened planets.

Keywords: Open source software, Oblateness, Exoplanet systems
The First Identification of Lyα Changing-look Quasars at High Redshift in DESI. We present two cases of Lyα changing-look (CL) quasars (J1306 and J1512) along with two additional candidates (J1511 and J1602), all discovered serendipitously at z &gt; 2 through the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey. It is the first time to capture CL events in Lyα at high redshift, which is crucial for understanding the underlying mechanisms driving the CL phenomenon and the evolution of high-redshift quasars and galaxies. We find that the accretion rate in the dim state for these CL objects corresponds to a relatively low value ( ), which suggests that the inner region of the accretion disk might be in transition between the advection dominated accretion flow ( ) and the canonical accretion disk (optically thick, geometrically thin). However, unlike in C IV CL quasars in which broad Lyα remained, the broad C IV may still persist after a CL event occurs in Lyα, making the physical origin of the CL and ionization mechanism event more puzzling and interesting.

Keywords: Accretion, Supermassive black holes, Active galaxies, Quasars
Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z &gt; 2 with JWST. The James Webb Space Telescope (JWST) is opening new frontiers of transient discovery and follow-up at high redshift. Here we present the discovery of a spectroscopically confirmed Type Ia supernova (SN Ia; SN 2023aeax) at z = 2.15 with JWST, including a NIRCam multiband light curve. SN 2023aeax lands at the edge of traditional low-z cosmology cuts because of its blue color (peak rest-frame B ‑ V ∼ ‑0.3) but with a normal decline rate (Δm15(B) ∼ 1.25), and applying a fiducial standardization with the BayeSN model we find the SN 2023aeax luminosity distance is in ∼0.1σ agreement with ΛCDM. SN 2023aeax is only the second spectroscopically confirmed SN Ia in the dark matter–dominated Universe at z &gt; 2 (the other is SN 2023adsy), giving it rare leverage to constrain any potential evolution in SN Ia standardized luminosities. Similar to SN 2023adsy (B ‑ V ∼ 0.8), SN 2023aeax has a fairly extreme (but opposite) color, which may be due to the small sample size or a secondary factor, such as host galaxy properties. Nevertheless, the SN 2023aeax spectrum is well represented by normal low-z SN Ia spectra, and we find no definitive evolution in SN Ia standardization with redshift. Still, the first two spectroscopically confirmed z &gt; 2 SNe Ia have peculiar colors and combine for a ∼1σ distance slope relative to ΛCDM, though in agreement with recent SN Ia cosmological measurements.

Keywords: Cosmology, Cosmological evolution, Type Ia supernovae, Galaxy evolution
Multimission Observations of Relativistic Electrons and High-speed Jets Linked to Shock-generated Transients. Shock-generated transients, such as hot flow anomalies (HFAs), upstream of planetary bow shocks, play a critical role in electron acceleration. Using multimission data from NASA's Magnetospheric Multiscale and ESA's Cluster missions, we demonstrate the transmission of HFAs through Earth's quasi-parallel bow shock, accelerating electrons to relativistic energies in the process. Energetic electrons initially accelerated upstream are shown to remain broadly confined within the transmitted transient structures downstream, where they get further energized due to the elevated compression levels potentially by betatron acceleration. Additionally, high-speed jets form at the compressive edges of HFAs, exhibiting a significant increase in dynamic pressure and potentially contributing to further localized compression. Our findings emphasize the efficiency of quasi-parallel shocks in driving particle acceleration far beyond the immediate shock transition region, expanding the acceleration region to a larger spatial domain. Finally, this study underscores the importance of a multiscale observational approach in understanding the convoluted processes behind collisionless shock physics and their broader implications.

Keywords: Space plasmas, Interplanetary shocks, Heliosphere, Fast solar wind, Plasma physics, Space weather, Planetary bow shocks, Plasma astrophysics, Solar-terrestrial interactions, Shocks
Radiative Cooling Changes the Dynamics of Magnetically Arrested Disks. We study magnetically arrested disks (MADs) around rotating black holes (BHs) under the influence of radiative cooling. We introduce a critical value of the mass accretion rate   for which the cooling by the synchrotron process efficiently radiates the thermal energy of the disk. We find  , where   is the Eddington mass accretion rate. The normalization constant depends on the saturated magnetic flux and on the ratio of electron to proton temperatures, but not on the BH mass. We verify our analytical estimate using a suite of general relativistic magnetohydrodynamic simulations for a range of BH spin parameters a ∈ {‑0.94, ‑0.5, 0, 0.5, 0.94} and mass accretion rates ranging from   to  . We numerically observe that the MAD parameter and the jet efficiency vary by a factor of ≈2 as the mass accretion rate increases above  , which confirms our analytical result. We further detail how the forces satisfying the quasi-equilibrium of the disk change, with the magnetic contribution increasing as the thermal contribution decreases.

Keywords: Accretion, Black hole physics, Magnetohydrodynamical simulations
Kite-borne Spectroscopic Observations of the Corona During the 2023 April 20 Total Solar Eclipse. We report in this Letter on the first use of a kite as an airborne platform for coronal observations during total solar eclipses, to mitigate the detrimental impact of clouds when present. In this first innovative attempt, the scientific payload was chosen to be a single-channel color spectrometer operating in high order over the wavelength range of 400–1000 nm, with light being fed from a coelostat that tracked the Sun optically. The payload was made airborne by a Cody-box-type kite with a wingspan of 6.5 m and launched from Cape Range National Park in North West Australia during the 2023 April 20 total solar eclipse. The kite and payload reached a terminal altitude of 450 m about 30 minutes prior to second contact and remained airborne 1 hr past the 58 s of totality. Although the tracking was not perfect, it nevertheless enabled the acquisition of two coronal spectra. This first successful technology demonstration paves the way for the feasibility of future low-cost kite-borne payloads for astronomical observations not limited to total solar eclipses.

Keywords: Solar corona, Spectroscopy