Sazuna/UAT_keywords huggingface dataset:
Mira Ceti, Atypical Archetype. With the aim of unraveling the complexity of the morphokinematics of the circumstellar envelope (CSE) of Mira Ceti, we review, extend, and in some cases revisit Atacama Large Millimeter/submillimeter Array observations of the emission of the SiO(5-4) and CO(3-2) molecular lines. In addition, we present a detailed analysis of the optically thin 13CO(3-2) emission, which provides several important new results. In agreement with observations at infrared and visible wavelengths, we give evidence for the confinement and probably rotation of a dense gas volume within ~50 au from the star and for a large SiO line width within ~15 au. We show that the mass-loss process is episodic and takes the form of clumps having a very low SiO/CO abundance ratio compared with similar oxygen-rich long-period variables, probably a result of depletion on dust grains and photodissociation. We evaluate the mass-loss rate associated with the main clumps and compare it with values obtained from single-dish observations. We argue that the SiO emission observed in the southwestern quadrant is not related to the mechanism of generation of the nascent wind but to a mass ejection that occurred 11 years before the observations. We remark that Mira Ceti is not a good archetype in terms of its wind: models aiming at describing the very complex gas-dust chemistry in action in the CSE of oxygen-rich AGB stars may find it difficult to account for its peculiar features and small variations in the parameters deciding when and where mass loss can proceed significantly.

Keywords: Circumstellar matter, Asymptotic giant branch stars
On the Stellar Populations of Galaxies at z = 9-11: The Growth of Metals and Stellar Mass at Early Times. We present a detailed stellar population analysis of 11 bright (H &lt; 26.6) galaxies at z = 9-11 (three spectroscopically confirmed) to constrain the chemical enrichment and growth of stellar mass of early galaxies. We use the flexible Bayesian spectral energy distribution (SED) fitting code Prospector with a range of star formation histories (SFHs), a flexible dust attenuation law, and a self-consistent model of emission lines. This approach allows us to assess how different priors affect our results and how well we can break degeneracies between dust attenuation, stellar ages, metallicity, and emission lines using data that probe only the rest-frame ultraviolet (UV) to optical wavelengths. We measure a median observed UV spectral slope $\beta =-{1.87}_{-0.43}^{+0.35}$ for relatively massive star-forming galaxies ( $9\lt \mathrm{log}({M}_{\star }/{M}_{\odot })\lt 10$ ), consistent with no change from z = 4 to z = 9-10 at these stellar masses, implying rapid enrichment. Our SED-fitting results are consistent with a star-forming main sequence with sublinear slope (0.7 ± 0.2) and specific star formation rates of 3-10 Gyr-1. However, the stellar ages and SFHs are less well constrained. Using different SFH priors, we cannot distinguish between median mass-weighted ages of ~ 50-150 Myr, which corresponds to 50% formation redshifts of z 50 ~ 10-12 at z ~ 9 and is of the order of the dynamical timescales of these systems. Importantly, models with different SFH priors are able to fit the data equally well. We conclude that the current observational data cannot tightly constrain the mass-buildup timescales of these z = 9-11 galaxies, with our results consistent with SFHs implying both a shallow and steep increase in the cosmic SFR density with time at z &gt; 10.

Keywords: Early universe, Galaxy formation, Star formation, Galaxy evolution, High-redshift galaxies
A Case Study of the Induced Magnetosphere Boundary at the Martian Subsolar Region. One Martian induced magnetosphere boundary (IMB) crossing at the subsolar region is analyzed here with multiple instruments on board MAVEN. Properties of the magnetic field and particles around the IMB are evaluated. We find different trends of variation in magnetic field components at the two sides of an interface coincident with the previously defined ion composition boundary. This case shows the IMB at the Martian dayside could be divided into three parts: two regions (denoted as R1 and R2), with different field and plasma properties, and an interface between them. Currents found in R1 and R2 are flowing in antiparallel, and the current density in R2 (at lower altitude) is significantly larger than that in R1 (at higher altitude). Results indicate the interaction between Mars and the solar wind could induce strong currents in the IMB, which are with antiparallel current directions and separated by an interface where the ion composition changes. This could be a typical feature that occurred during the interaction between the solar wind and the nonmagnetized planets.

Keywords: Mars, Planetary boundary layers
Non-Gaussian Generalization of the Kazantsev-Kraichnan Model for a Turbulent Dynamo. We consider a natural generalization of the Kazantsev-Kraichnan model for a small-scale turbulent dynamo. This generalization takes into account the statistical time asymmetry of a turbulent flow and thus allows one to describe velocity fields with energy cascade. For three-dimensional velocity fields, a generalized Kazantsev equation is derived, and the evolution of the second-order magnetic field correlator is investigated for large but finite magnetic Prandtl numbers. It is shown that as Pr m  → ∞, the growth increment tends to the limit known from the T-exponential (Lagrangian deformation) method. Magnetic field generation is shown to be weaker than that in the Gaussian velocity field for any direction of the energy cascade and essentially depends on the Prandtl number.

Keywords: Interstellar magnetic fields, Magnetohydrodynamics
Gamma-Ray Burst Prompt Emission Spectrum and E <SUB>p</SUB> Evolution Patterns in the ICMART Model. In this paper, we simulate the prompt emission light curve, spectrum, and E p evolution patterns of gamma-ray bursts (GRBs) within the framework of the Internal-collision-induced Magnetic Reconnection and Turbulence (ICMART) model. We show that this model can produce a Band-shaped spectrum, whose parameters (E p, α, β) could follow the typical distribution of GRB observations, as long as the magnetic field and the electron acceleration process in the emission region are under appropriate conditions. On the other hand, we show that for one ICMART event, E p evolution is always a hard-to-soft pattern. However, a GRB light curve is usually composed of multiple ICMART events that are fundamentally driven by the erratic activity of the GRB central engine. In this case, we find that if one individual broad pulse in the GRB light curve is composed of multiple ICMART events, the overall E p evolution could be disguised as an intensity-tracking pattern. Therefore, mixed E p evolution patterns can coexist in the same burst, with a variety of combined patterns. Our results support the ICMART model as a competitive model to explain the main properties of GRB prompt emission. The possible challenges faced by the ICMART model are also discussed in detail.

Keywords: Gamma-ray bursts
A Constraint on Primordial B-modes from the First Flight of the SPIDER Balloon-borne Telescope. We present the first linear polarization measurements from the 2015 long-duration balloon flight of SPIDER, which is an experiment that is designed to map the polarization of the cosmic microwave background (CMB) on degree angular scales. The results from these measurements include maps and angular power spectra from observations of 4.8% of the sky at 95 and 150 GHz, along with the results of internal consistency tests on these data. While the polarized CMB anisotropy from primordial density perturbations is the dominant signal in this region of sky, Galactic dust emission is also detected with high significance. Galactic synchrotron emission is found to be negligible in the SPIDER bands. We employ two independent foreground-removal techniques to explore the sensitivity of the cosmological result to the assumptions made by each. The primary method uses a dust template derived from Planck data to subtract the Galactic dust signal. A second approach, which constitutes a joint analysis of SPIDER and Planck data in the harmonic domain, assumes a modified-blackbody model for the spectral energy distribution of the dust with no constraint on its spatial morphology. Using a likelihood that jointly samples the template amplitude and r parameter space, we derive 95% upper limits on the primordial tensor-to-scalar ratio from Feldman-Cousins and Bayesian constructions, finding r &lt; 0.11 and r &lt; 0.19, respectively. Roughly half the uncertainty in r derives from noise associated with the template subtraction. New data at 280 GHz from SPIDER's second flight will complement the Planck polarization maps, providing powerful measurements of the polarized Galactic dust emission.

Keywords: Observational cosmology, Interstellar emissions, Cosmic microwave background radiation, Cosmological parameters
He II Lyα Transmission Spikes and Absorption Troughs in Eight High-resolution Spectra Probing the End of He II Reionization. We present statistics of He II Lyα transmission spikes and large-scale absorption troughs using archival high-resolution (R = λ/Δλ ≃ 12,500-18,000) far-UV spectra of eight He II-transparent quasars obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. The sample covers the redshift range 2.5 ≲ z ≲ 3.8, thereby probing the rapidly evolving He II absorption at the end of He II reionization epoch. The measured lengths of the troughs decrease dramatically from L ≳ 100 cMpc at z &gt; 3 to L ≃ 30 cMpc at z ~ 2.7, signaling a significant progression of He II reionization at these redshifts. Furthermore, unexpectedly long L ~ 65 cMpc troughs detected at z ≃ 2.9 suggest that the UV background fluctuates at larger scales than predicted by current models. By comparing the measured incidence of transmission spikes to predictions from forward-modeled mock spectra created from the outputs of a (146 cMpc)3 optically thin Nyx hydrodynamical simulation employing different UV background models, we infer the redshift evolution of the He II photoionization rate ΓHe II (z). The photoionization rate decreases with increasing redshift from ≃ 4.6 × 10-15 s-1 at z ≃ 2.6 to ≃ 1.2 × 10-15 s-1 at z ≃ 3.2, in agreement with previous inferences from the He II effective optical depth, and following expected trends of current models of a fluctuating He II-ionizing background.

Keywords: Quasar absorption line spectroscopy, Hubble Space Telescope, Ultraviolet astronomy, Intergalactic medium, Reionization, Cosmic background radiation
The Farthest Quasar Mini-Broad Absorption Line Outflow from Its Central Source: Very Large Telescope/UVES Observation of SDSS J0242+0049. We analyze Very Large Telescope/UVES observations of the quasar SDSS J024221.87+004912.6. We identify four absorption outflow systems: a C IV broad absorption line (BAL) at v ≍ −18,000 km s−1 and three narrower low-ionization systems with centroid velocities ranging from ─1200 to ─3500 km s−1. These outflows show similar physical attributes to the [O III] outflows studied by Liu et al. (2013). We find that two of the systems are energetic enough to contribute to active galactic nucleus feedback, with one system reaching above 5% of the quasar's Eddington luminosity. We also find that this system is at a distance of 67 kpc away from the quasar, the farthest detected mini-BAL absorption outflow from its central source to date. In addition, we examine the time-variability of the BAL and find that its velocity monotonically increases, while the trough itself becomes shallower over time.

Keywords: AGN host galaxies, Quasar absorption line spectroscopy, Quasars, Active galactic nuclei, Galaxies
Preferential Acceleration of Heavy Ions in a Spontaneously Fragmenting Flare Current Sheet. We study the ion acceleration in a mesoscale, spontaneously fragmenting flare current sheet (SFCS) characterized by the presence of a plasmoid cascade. The main subject of our investigation is to determine whether and how plasmoid cascades at intermediate scales in a fragmented current sheet of a solar flare can impact the (preferential) acceleration of specific ions. The time evolution of the SFCS is obtained from high-resolution 2.5D MHD simulations. The ion trajectories (in the background fields resulting from the MHD model), energies, and pitch angles are calculated using a relativistic test-particle code based on the half-acceleration-rotation-half-acceleration method. For light ions, the main acceleration effects of electromagnetic fields within the SFCS are analyzed using the guiding center approximation. We identify regions with the most-efficient ion acceleration within the SFCS, the accelerator efficiency, and spectra of the accelerated ions. The influence of the charge-to-mass ratio on ion behavior is also studied and resulting ion abundances are compared with observational data. The main ion acceleration takes place in the regions with a strong polarization term, which is part of the first-order Fermi acceleration. Because the term is mass dependent, heavier ions undergo preferential acceleration. The ion energy spectra, abundance-enhancement factors, and differential fluxes, obtained from the model, exhibit power-law profiles, in agreement with observed solar energetic particle events. Nonetheless, the obtained slopes for the abundance-enhancement factor do not exactly match the observed data. The computed slopes and profiles are not sensitive to changes in the initial plasma temperature.

Keywords: Solar flares, Solar magnetic reconnection, Solar energetic particles, Solar abundances, Active solar corona
On the Structure and Long-term Evolution of Ice-rich Bodies. The interest in the structure of ice-rich planetary bodies, in particular the differentiation between ice and rock, has grown due to the discovery of Kuiper Belt objects and exoplanets. We thus carry out a parameter study for a range of planetary masses M, yielding radii 50 ≲ R ≲ 3000 km, and for rock to ice mass ratios between 0.25 and 4, evolving them for 4.5 Gyr in a cold environment, to obtain the present structure. We use a thermal evolution model that allows for liquid and vapor flow in a porous medium, solving mass and energy conservation equations under hydrostatic equilibrium for a spherical body in orbit around a central star. The model includes the effect of pressure on porosity and on the melting temperature, heating by long-lived radioactive isotopes, and temperature-dependent serpentinization and dehydration. We obtain the boundary in parameter space (size, rock content) between bodies that differentiate, forming a rocky core, and those which remain undifferentiated: small bodies, bodies with a low rock content, and the largest bodies considered, which develop high internal pressures and barely attain the melting temperature. The final differentiated structure comprises a rocky core, an ice-rich mantle, and a thin dense crust below the surface. We obtain and discuss the bulk density-radius relationship. The effect of a very cold environment is investigated, and we find that at an ambient temperature of ~20 K, small bodies preserve the ice in amorphous form to the present.

Keywords: Exoplanet evolution, Planetary interior, Kuiper belt, Planetary structure
Universal Scaling Laws for Solar and Stellar Atmospheric Heating. The Sun and Sun-like stars commonly host multimillion-kelvin coronae and 10,000 K chromospheres. These extremely hot gases generate X-ray and extreme ultraviolet emissions that may impact the erosion and chemistry of (exo)planetary atmospheres, influencing the climate and conditions for habitability. However, the mechanism of coronal and chromospheric heating is still poorly understood. While the magnetic field most probably plays a key role in driving and transporting energy from the stellar surface upwards, it is not clear whether the atmospheric heating mechanisms of the Sun and active Sun-like stars can be described in a unified manner. To this end, we report on a systematic survey of the responses of solar and stellar atmospheres to surface magnetic flux over a wide range of temperatures. By analyzing 10 years of multiwavelength synoptic observations of the Sun, we reveal that the irradiance and magnetic flux show power-law relations with an exponent decreasing from above unity to below as the temperature decreases from the corona to the chromosphere. Moreover, this trend indicating the efficiency of atmospheric heating can be extended to Sun-like stars. We also discover that the power-law exponent depends on the solar cycle, becoming smallest at maximum activity, probably due to the saturation of atmospheric heating. Our study provides observational evidence that the mechanism of atmospheric heating is universal among the Sun and Sun-like stars, regardless of age or activity.

Keywords: Solar analogs, G dwarf stars, Solar chromospheric heating, Stellar chromospheres, Solar coronal heating, Stellar magnetic fields, Solar magnetic fields, Stellar coronae
The Type Icn SN 2021csp: Implications for the Origins of the Fastest Supernovae and the Fates of Wolf-Rayet Stars. We present observations of SN 2021csp, the second example of a newly identified type of supernova (SN) hallmarked by strong, narrow, P Cygni carbon features at early times (Type Icn). The SN appears as a fast and luminous blue transient at early times, reaching a peak absolute magnitude of -20 within 3 days due to strong interaction between fast SN ejecta (v ≍ 30,000 km s-1) and a massive, dense, fast-moving C/O wind shed by the WC-like progenitor months before explosion. The narrow-line features disappear from the spectrum 10-20 days after explosion and are replaced by a blue continuum dominated by broad Fe features, reminiscent of Type Ibn and IIn supernovae and indicative of weaker interaction with more extended H/He-poor material. The transient then abruptly fades ~60 days post-explosion when interaction ceases. Deep limits at later phases suggest minimal heavy-element nucleosynthesis, a low ejecta mass, or both, and imply an origin distinct from that of classical Type Ic SNe. We place SN 2021csp in context with other fast-evolving interacting transients, and discuss various progenitor scenarios: an ultrastripped progenitor star, a pulsational pair-instability eruption, or a jet-driven fallback SN from a Wolf-Rayet (W-R) star. The fallback scenario would naturally explain the similarity between these events and radio-loud fast transients, and suggests a picture in which most stars massive enough to undergo a W-R phase collapse directly to black holes at the end of their lives.

Keywords: Core-collapse supernovae, Transient sources, Stellar mass black holes, Wolf-Rayet stars, Supernovae
3D Kinematics of Stellar SiO Masers in the Galactic Center. We present 3D velocity measurements and acceleration limits for stars within a few parsec of the Galactic Center (GC) black hole, Sgr A*, based on observations of 43 and 86 GHz circumstellar maser emission. Observations were taken with the Very Large Array in 2013, 2014, and 2020 and with the Atacama Large Millimeter/submillimeter Array in 2015 and 2017. We detect 28 masers in total, of which four are new detections. Combining these data with extant maser astrometry, we calculate stellar proper motions and accelerations with uncertainties as low as ~10 μas yr-1 and 0.5 μas yr-2, respectively, corresponding to approximately 0.5 km s-1 and 0.04 km s-1 yr-1 at a distance of 8 kpc. We measure radial velocities from maser spectra with ~0.5 km s-1 uncertainties, though the precision and accuracy of such measurements for deducing the underlying stellar velocities are limited by the complex spectral profiles of some masers. We therefore measure radial acceleration limits with typical uncertainties of ~0.1 km s-1 yr-1. We analyze the resulting 3D velocities and accelerations with respect to expected motions resulting from models of the mass distribution in the GC.

Keywords: Stellar kinematics, Silicon monoxide masers, Galactic center, Astrophysical masers
Solar Wind Magnetic Field Correlation Length: Correlation Functions versus Cross-field Displacement Diffusivity Test. The estimate of the solar wind magnetic fields' parallel correlation length, λ, be it from the measured fields' correlation functions or their spectral power at "zero" frequency, have long pointed toward short values on the order of 0.01 au. Evaluation of the mean cross-field displacements (CFDs), however, fails to show the decorrelation and resulting diffusion at the expected scales, pointing instead toward λ values on the order of 0.1 au or more. In an effort to understand this "order-of-magnitude" discrepancy and reconcile the approaches using correlation functions and the CFD diffusivity test, both approaches are applied here, with renewed attention to the "details" as well as the broader sense of the calculations, to a large, 20 yr long set of magnetic field and flow data from the ACE spacecraft. It is found that solar wind intervals too short relative to λ are a likely reason for some underestimate through the correlation-function approach, causing a premature drop of the correlation functions. Once converged to their long-time limit, however, the correlation functions produce magnetic field correlation lengths very much consistent with the magnetic-field-line (MFL) correlation lengths of the diffusivity test, with nearly matching distributions of the correlation lengths corrected by the proper ratio of their theoretical estimates. The fields' correlation lengths mostly range from 0.03 to 0.08 au, and the MFL correlation lengths from 0.04 to 0.3 au, with peaks at 0.075 and 0.15 au, likely due to nonlinear and quasilinear regimes of MFL wandering. As for the power-at-zero-frequency approach, it is doomed by the solar rotation.

Keywords: Interplanetary turbulence, Space plasmas, Magnetic fields, Heliosphere
A Single-lined Spectroscopic Binary Companion to an Active and Deep Contact Binary in a Quintuple Stellar System. V410 Aur is a known deep and low-mass-ratio contact binary with a spectroscopically tertiary component and a visual companion. However, the physical and orbital properties of the tertiary are unknown. We constructed (O - C) curve with 117 new eclipse times and those collected from the literature, which shows a cyclical variation with a period of 25.44 (±1.17) yr and a projected semimajor axis of 0.0348 (±0.0021) days while it undergoes a long-term period decrease at a rate of dP/dt = -1.58 × 10-7daysyr-1. The cyclical variation is analyzed for the light-travel time effect. The minimum mass of the third body is determined as 1.39 (±0.13) M ⊙ that is much larger than the inferred value (0.97 M ⊙) of spectroscopic investigation, which indicates that the spectroscopically tertiary is a single-lined spectroscopic binary with an unseen component. The maximum orbital semimajor axis 6.19 (±0.67) au of the third body is determined. Gaia detected a visual companion to V410 Aur at practically the same distance from the Sun nicely confirming the physical bond. These results reveal that V410 Aur contains a single-lined spectroscopic binary with a visual companion in a quintuple stellar system. TESS photometric solutions confirmed that V410 Aur is a deep overcontact binary with a fill-out factor of 73.83(88)% where the additional light contribution is about 24.80(18)%. The continuous variations of light curves are explained by the evolution of a dark spot on the more massive component. The parabolic variation in the (O - C) curve may be caused by the mass transfer from the massive component to the less massive one in the deep overcontact binary.

Keywords: Eclipsing binary stars, Close binary stars