Sazuna/UAT_keywords huggingface dataset:
Can Emission Measure Distributions Derived from Extreme-ultraviolet Images Accurately Constrain High-temperature Plasma?. Measuring the relative amount of high-temperature, low emission measure (EM) plasma is considered to be a smoking-gun observation to constrain the frequency of plasma heating in coronal structures. Often, narrowband, extreme-ultraviolet images, such as those obtained by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO), are used to determine the EM distribution, though the sensitivity to high-temperature plasma is limited. Conversely, the soft X-ray wavelength range offers multiple high-temperature diagnostics, including emission lines of N VII, O VII, O VIII, Fe XVII, Ne IX, and Mg XI, which can provide tight constraints to the high-temperature plasma in the log T = 6.1–6.7 (∼1–5+ MK) range. The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS), a slitless spectrograph launched on a NASA sounding rocket on 2021 July 30, resolved an X-ray-bright point in multiple emission lines in the soft X-ray wavelength range. Using coordinated observations of the same X-ray-bright point from SDO/AIA, we compare and contrast the EM distributions from the EUV image data, the X-ray spectra, and the combined EUV and X-ray data set. In this paper, we demonstrate that EM distributions from SDO/AIA data alone can overestimate the amount of high-temperature (log T &gt; 6.4) plasma in the solar corona by a factor of 3–15. Furthermore, we present our effort to cross-calibrate Hinode/X-ray Telescope (XRT) response functions by comparing the observed XRT fluxes with the predicted ones from combined MaGIXS-1 + AIA EM analysis.

Keywords: Solar extreme ultraviolet emission, Solar coronal heating, Solar x-ray emission, Solar active regions, Solar corona
What is the Reynolds Number of the Solar Wind?. The Reynolds number, Re, is an important quantity for describing a turbulent flow. It tells us about the bandwidth over which energy can cascade from large scales to smaller ones, prior to the onset of dissipation. However, calculating it for nearly collisionless plasmas like the solar wind is challenging. Previous studies have used formulations of an "effective" Reynolds number, expressing Re as a function of the correlation scale and either the Taylor scale or a proxy for the dissipation scale. We find that the Taylor scale definition of the Reynolds number has a sizable prefactor of approximately 27, which has not been employed in previous works. Drawing from 18 years of data from the Wind spacecraft at 1 au, we calculate the magnetic Taylor scale directly and use both the ion inertial length and the magnetic spectrum break scale as approximations for the dissipation scale, yielding three distinct Re estimates for each 12 hr interval. Average values of Re range between 116,000 and 3,406,000 within the general distribution of past work. We also find considerable disagreement between the methods, with linear associations of between 0.38 and 0.72. Although the Taylor scale method is arguably more physically motivated, due to its dependence on the energy cascade rate, more theoretical work is needed in order to identify the most appropriate way of calculating effective Reynolds numbers for kinetic plasmas. As a summary of our observational analysis, we make available a data product of 28 years of 1 au solar wind and magnetospheric plasma measurements from Wind.

Keywords: Interplanetary turbulence, Space plasmas, Magnetohydrodynamics, Solar wind
Filament Formation due to Diffusive Instabilities in Dusty Protoplanetary Disks. We report the finding of a new, local diffusion instability in a protoplanetary disk which can operate in a dust fluid, subject to mass diffusion, shear viscosity, and dust–gas drag, provided the diffusivity, viscosity, or both, decrease sufficiently rapidly with increasing dust surface mass density. We devise a vertically averaged, axisymmetric hydrodynamic model to describe a dense, midplane dust layer in a protoplanetary disk. The gas is modeled as a passive component, imposing an effective, diffusion-dependent pressure, mass diffusivity, and viscosity onto the otherwise collisionless dust fluid, via turbulence excited by the gas alone, or dust and gas in combination. In particular, we argue that such conditions are met when the dust–gas mixture generates small-scale turbulence through the streaming instability, as supported by recent measurements of dust mass diffusion slopes in simulations. We hypothesize that the newly discovered instability may be the origin of filamentary features, almost ubiquitously found in simulations of the streaming instability. In addition, our model allows for growing oscillatory modes, which operate in a similar fashion as the axisymmetric viscous overstability in dense planetary rings. However, it remains speculative if the required conditions for such modes can be met in protoplanetary disks.

Keywords: Hydrodynamics, Astrophysical dust processes, Protoplanetary disks, Circumstellar dust, Astrophysical fluid dynamics, Planet formation
Toward the IR Detection of Carbonic Acid: Absorption and Emission Spectra. With the recent radioastronomical detection of cis-trans-carbonic acid (H2CO3) in a molecular cloud toward the Galactic center, the more stable but currently unobserved cis-cis conformer is shown here to have strong IR features. While the higher-energy cis-trans-carbonic acid was detected at millimeter and centimeter wavelengths, owing to its larger dipole moment, the vibrational structure of cis-cis-carbonic acid is more amenable to its observation at micron wavelengths. Even so, both conformers have relatively large IR intensities, and some of these fall in regions not dominated by polycyclic aromatic hydrocarbons. Water features may inhibit observation near the 2.75 μm hydride stretches, but other vibrational fundamentals and even overtones in the 5.5–6.0 μm range may be discernible with JWST data. This work has employed high-level, accurately benchmarked quantum chemical anharmonic procedures to compute exceptionally accurate rotational spectroscopic data compared to experiment. Such performance implies that the IR absorption and even cascade emission spectral features computed in this work should be accurate and will provide the needed reference for observation of either carbonic acid conformer in various astronomical environments.

Keywords: Interstellar molecules, Complex organic molecules, Molecular data, Infrared spectroscopy, Rotational spectroscopy, Molecular spectroscopy, Molecular spectroscopic constants, Astrochemistry, Quantum-chemical calculations, Small molecules, Pre-biotic astrochemistry
Environmental Dependence of Type Ia Supernovae in Low-redshift Galaxy Clusters. We present an analysis of 102 Type Ia supernovae (SNe Ia) in nearby (z &lt; 0.1), x-ray-selected galaxy clusters. This is the largest such sample to date and is based on archival data primarily from ZTF and ATLAS. We divide our SNe Ia into an inner cluster sample projected within r 500 of the cluster center and an outer cluster sample projected between r 500 and 2 r 500. We compare these to field samples of SNe Ia at similar redshifts in both quiescent and star-forming host galaxies. Based on SALT3 fits to the light curves, we find that the inner cluster SNe Ia have a higher fraction of fast-evolving objects (SALT3 x 1 &lt; −1) than the outer cluster or field quiescent samples. This implies an intrinsically different population of SNe Ia occurs in inner cluster environments, beyond known correlations based on host galaxy alone. Our cluster samples show a strongly bimodal x 1 distribution with a fast-evolving component that dominates the inner cluster objects (≳75%) but is just a small fraction of SNe Ia in field star-forming galaxies (≲10%). We do not see strong evidence for variations in the color (SALT3 c) distributions among the samples and find only minor differences in SN Ia standardization parameters and Hubble residuals. We suggest that the age of the stellar population drives the observed distributions, with the oldest populations nearly exclusively producing fast-evolving SNe Ia.

Keywords: Galaxy clusters, Cosmological parameters, Light curves, Type Ia supernovae, Field galaxies
Precision MARS Mass Reconstruction of A2744: Synergizing the Largest Strong-lensing and Densest Weak-lensing Data Sets from JWST. We present a new high-resolution free-form mass model of A2744 that combines both weak-lensing (WL) and strong-lensing (SL) data sets from JWST. The SL data set comprises 286 multiple images, presenting the most extensive SL constraint to date for a single cluster. The WL data set, employing photo-z selection, yields a source density of $\sim 350\,{\mathrm{arcmin}}^{-2}$ , marking the densest WL constraint ever. The combined mass reconstruction enables the highest-resolution mass map of A2744 within the ∼1.8 Mpc × 1.8 Mpc reconstruction region to date, revealing an isosceles triangular structure with two legs of ∼1 Mpc and a base of ∼0.6 Mpc. Although our algorithm, which is called MAximum-entropy ReconStruction (MARS), is entirely blind to the cluster galaxy distribution, the resulting mass reconstruction traces the brightest cluster galaxies remarkably well. The five strongest mass peaks coincide with the five most luminous cluster galaxies within ≲2″. We do not detect any unusual mass peaks that are not traced by the cluster galaxies, unlike the findings in previous studies. Our mass model shows the smallest scatter of SL multiple images in both source (∼0.″05) and image (∼0.″1) planes, which is lower than in previous studies by a factor of ∼4. Although MARS represents the mass field with an extremely large number of free parameters (∼300,000), it converges to a solution within a few hours because we use a deep-learning technique. We make our mass and magnification maps publicly available.

Keywords: Weak gravitational lensing, Dark matter distribution, Galaxy clusters, Strong gravitational lensing
JWST MIRI/Medium Resolution Spectrograph (MRS) Observations and Spectral Models of the Underluminous Type Ia Supernova 2022xkq. We present a JWST mid-infrared (MIR) spectrum of the underluminous Type Ia Supernova (SN Ia) 2022xkq, obtained with the medium-resolution spectrometer on the Mid-Infrared Instrument (MIRI) ∼130 days post-explosion. We identify the first MIR lines beyond 14 μm in SN Ia observations. We find features unique to underluminous SNe Ia, including the following: isolated emission of stable Ni, strong blends of [Ti II], and large ratios of singly ionized to doubly ionized species in both [Ar] and [Co]. Comparisons to normal-luminosity SNe Ia spectra at similar phases show a tentative trend between the width of the [Co III] 11.888 μm feature and the SN light-curve shape. Using non-LTE-multi-dimensional radiation hydro simulations and the observed electron capture elements, we constrain the mass of the exploding WD. The best-fitting model shows that SN 2022xkq is consistent with an off-center delayed-detonation explosion of a near-Chandrasekhar mass WD ( ${M}_{{\rm{WD}}}$ ≈1.37 M ⊙) of high central density (ρ  c  ≥ 2.0 × 109 g cm‑3) seen equator-on, which produced M(56Ni) =0.324 M ⊙ and M(58Ni) ≥0.06 M ⊙. The observed line widths are consistent with the overall abundance distribution; and the narrow stable Ni lines indicate little to no mixing in the central regions, favoring central ignition of subsonic carbon burning followed by an off-center deflagration-to-detonation transition beginning at a single point. Additional observations may further constrain the physics revealing the presence of additional species including Cr and Mn. Our work demonstrates the power of using the full coverage of MIRI in combination with detailed modeling to elucidate the physics of SNe Ia at a level not previously possible.

Keywords: James Webb Space Telescope, Type Ia supernovae, Supernovae
An Updated Modular Set of Synthetic Spectral Energy Distributions for Young Stellar Objects. Measured properties of young stellar objects (YSOs) are key tools for research into pre-main-sequence stellar evolution. YSO properties are commonly measured by comparing observed radiation to existing grids of template YSO spectral energy distributions (SEDs) calculated by radiative transfer. These grids are often sampled and constructed using simple models of mass assembly/accretion over time. However, because we do not yet have a complete theory of star formation, the choice of model sets the tracked parameters and range of allowed values. By construction, then, the assumed model limits the measurements that can be made using the grid. Radiative transfer models not constrained by specific accretion histories would enable assessment of a wider range of theories. We present an updated version of the Robitaille set (2017) of YSO SEDs, a collection of models with no assumed evolutionary theory. We outline our newly calculated properties: envelope mass, weighted-average dust temperature, disk stability, and circumstellar A V. We also convolve the SEDs with new filters, including JWST, and provide users the ability to perform additional convolutions. We find a correlation between the average temperature and millimeter-wavelength brightness of optically thin dust in our models and discuss its ramifications for mass measurements of pre- and protostellar cores. We also compare the positions of YSOs of different observational classes and evolutionary stages in IR color space and use our models to quantify the extent to which class and stage may be confused due to observational effects. Our updated models are released to the public.

Keywords: Protostars, Star formation, Astronomy databases, Radiative transfer
Apache Point Observatory (APO)/SMARTS Flare Star Campaign Observations. I. Blue Wing Asymmetries in Chromospheric Lines during Mid-M-Dwarf Flares from Simultaneous Spectroscopic and Photometric Observation Data. We conducted the time-resolved simultaneous optical spectroscopic and photometric observations of mid-M-dwarf flare stars YZ CMi, EV Lac, and AD Leo. Spectroscopic observations were obtained using Apache Point Observatory 3.5 m and Small and Moderate Aperture Research Telescope System 1.5 m telescopes during 31 nights. Among the 41 detected flares, seven flares showed clear blue wing asymmetries in the Hα line, with various correspondences in flare properties. The duration of the blue wing asymmetries range from 20 minutes to 2.5 hr, including a flare showing the shift from blue to red wing asymmetry. Blue wing asymmetries can be observed during both white-light and candidate non-white-light flares. All of the seven flares showed blue wing asymmetries also in the Hβ line, but there are large varieties on which other chromospheric lines showed blue wing asymmetries. One among the 7 flares was also observed with soft X-ray spectroscopy, which enabled us to estimate the flare magnetic field and length of the flare loop. The line-of-sight velocities of the blueshifted components range from ─73 to ─122 km s−1. Assuming that the blueshifts were caused by prominence eruptions, the mass of upward-moving plasma was estimated to be 1015─1019 g, which are roughly on the relation between flare energy and erupting mass expected from solar coronal mass ejections (CMEs). Although further investigations are necessary for understanding the observed various properties, these possible prominence eruptions on M-dwarfs could evolve into CMEs, assuming the similar acceleration mechanism with solar eruptions.

Keywords: M dwarf stars, Stellar x-ray flares, Stellar chromospheres, Red dwarf flare stars, Flare stars, Stellar flares, Optical flares, Stellar coronal mass ejections
Maser Investigation toward Off-Plane Stars (MIOPS): Detection of SiO Masers in the Galactic Thick Disk and Halo. Studying stars that are located off the Galactic plane is important for understanding the formation history of the Milky Way. We searched for SiO masers toward off-plane O-rich asymptotic giant branch (AGB) stars from the catalog presented by Mauron et al. in order to shed light on the origins of these objects. A total of 102 stars were observed in the SiO J = 1‑0, v = 1 and 2 transitions with the Effelsberg 100 m and Tianma 65 m telescopes. SiO masers were discovered in eight stars, all first detections. The measured maser velocities allow for initial estimates of the host AGB stars' radial velocities. We find that the radial velocities of three stars (namely G068.881‑24.615, G070.384‑24.886, and G084.453‑21.863) significantly deviate from the values expected from Galactic circular motion. The updated distances and 3D motions indicate that G068.881‑24.615 is likely located in the Galactic halo, while G160.648‑08.846 is probably located in the Galactic thin disk, and the other six stars are probably part of the Galactic thick disk.

Keywords: Silicon monoxide masers, Asymptotic giant branch stars, Galaxy structure, Astrophysical masers
Taking Titan's Boreal Pole Temperature: Evidence for Evaporative Cooling in Ligeia Mare. From 2004 to 2017, the Cassini RADAR recorded the 2.2 cm thermal emission from Titan's surface in its passive (radiometry) mode of operation. We use this data set to investigate the seasonal evolution of the effective temperature sensed by the microwave radiometer in two regions in the northern pole of the satellite: the sea Ligeia Mare, and its nearby solid terrains. We find that despite the arrival of summer at the end of the mission, the effective temperature of Ligeia Mare decreased by almost 1 K, while that of the solid region slowly increased until 2017 by 1.4 ± 0.3 K. These observations, as well as the lag in summer warming observed by Cassini's Composite Infrared Spectrometer, can be explained by evaporative cooling in both the solid and liquid surfaces after the vernal equinox. It therefore supports the idea that the northern polar terrains are wet. Using an ocean circulation model, we show that the cooling of the sea surface should initiate convection in the sea's interior, ultimately cooling the whole liquid column sensed by the Cassini radiometer and thus decreasing the temperature at depths even long after the evaporation period has ceased. Overall, this work highlights the key role of methane hydrology in controlling the surface and submarine temperatures in the boreal polar regions of Titan.

Keywords: Planetary polar regions, Effective temperature, Brightness temperature, Titan, Astronomy data analysis, Radar observations
Environment of Quiescent Low-mass Galaxies Hosting AGNs in MaNGA. The discovery of active galactic nuclei (AGNs) in low-mass (M * ≤ 5 × 109 M ⊙) galaxies has pushed forward the idea that AGN feedback may play a role in quenching star formation in the low-mass regime. In order to test whether AGNs can be a dominant quenching mechanism, we must first disentangle the effects of internal and external processes caused by a galaxy's environment. We have used the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory survey to produce resolved Baldwin, Phillips, &amp; Terlevich diagrams, and we find 41 AGNs (∼1.3%) in low-mass galaxies. We have studied the group richness (the number of group members) of our AGN and non-AGN samples as a proxy for determining the possible effect of the environment on the gas reservoir in these galaxies. We find that low-mass galaxies hosting AGNs are more likely to be found in isolation or in low-mass groups than galaxies in the non-AGN samples. This preference is even more clear when we split our samples into star-forming and quiescent subsamples. This suggests that environment is not the main cause of quenching in these galaxies, though we cannot rule out the possibility of past mergers.

Keywords: Galaxy quenching, Dwarf galaxies, Active galaxies, Galaxy environments
Gas Morphology of Milky Way–like Galaxies in the TNG50 Simulation: Signals of Twisting and Stretching. We present an in-depth analysis of gas morphologies for a sample of 25 Milky Way–like galaxies from the IllustrisTNG TNG50 simulation. We constrain the morphology of cold, warm, hot gas, and gas particles as a whole using a local shell iterative method and explore its observational implications by computing the hard-to-soft X-ray ratio, which ranges between 10‑3 and 10‑2 in the inner ∼50 kpc of the distribution and 10‑5–10‑4 at the outer portion of the hot gas distribution. We group galaxies into three main categories: simple, stretched, and twisted. These categories are based on the radial reorientation of the principal axes of the reduced inertia tensor. We find that a vast majority (77%) of the galaxies in our sample exhibit twisting patterns in their radial profiles. Additionally, we present detailed comparisons between (i) the gaseous distributions belonging to individual temperature regimes, (ii) the cold gas distributions and stellar distributions, and (iii) the gaseous distributions and dark matter (DM) halos. We find a strong correlation between the morphological properties of the cold gas and stellar distributions. Furthermore, we find a correlation between gaseous distributions with a DM halo that increases with gas temperature, implying that we may use the warm–hot gaseous morphology as a tracer to probe the DM morphology. Finally, we show gaseous distributions exhibit significantly more prolate morphologies than the stellar distributions and DM halos, which we hypothesize is due to stellar and active galactic nucleus feedback.

Keywords: Galaxy dark matter halos, Circumgalactic medium, Milky Way Galaxy, Magnetohydrodynamical simulations
A New Kilohertz Gravitational-wave Feature from Rapidly Rotating Core-collapse Supernovae. We present self-consistent three-dimensional core-collapse supernova simulations of a rotating 20M ⊙ progenitor model with various initial angular velocities from 0.0 to 4.0 rad s‑1 using the smoothed particle hydrodynamics code SPHYNX and the grid-based hydrodynamics code FLASH. We identify two strong gravitational-wave features with peak frequencies of ∼300 Hz and ∼1.3 kHz in the first 100 ms postbounce. We demonstrate that these two features are associated with the m = 1 deformation from the proto-neutron star (PNS) modulation induced by the low-T/∣W∣ instability, regardless of the simulation code. The 300 Hz feature is present in models with an initial angular velocity between 1.0 and 4.0 rad s‑1, while the 1.3 kHz feature is only present in a narrower range, from 1.5 to 3.5 rad s‑1. We show that the 1.3 kHz signal originates from the high-density inner core of the PNS, and the m = 1 deformation triggers a strong asymmetric distribution of electron antineutrinos. In addition to the 300 Hz and 1.3 kHz features, we also observe one weaker but noticeable gravitational-wave feature from higher-order modes in the range between 1.5 and 3.5 rad s‑1. Its initial peak frequency is around 800 Hz, and it gradually increases to 900–1000 Hz. Therefore, in addition to the gravitational bounce signal, the detection of the 300 Hz, 1.3 kHz, the higher-order mode, and even the related asymmetric emission of neutrinos could provide additional diagnostics for estimating the initial angular velocity of a collapsing core.

Keywords: Gravitational wave astronomy, Hydrodynamical simulations, Neutron stars, Core-collapse supernovae