Sazuna/UAT_keywords huggingface dataset:
Uniform Forward-modeling Analysis of Ultracool Dwarfs. III. Late-M and L Dwarfs in Young Moving Groups, the Pleiades, and the Hyades. We present a uniform forward-modeling analysis of 90 late-M and L dwarfs in nearby young (~10-200 Myr) moving groups, the Pleiades, and the Hyades using low-resolution (R ≈ 150) near-infrared (0.9-2.4 μm) spectra and the BT-Settl model atmospheres. We derive the objects' effective temperatures, surface gravities, radii, and masses by comparing our spectra to the models using a Bayesian framework with nested sampling and calculate the same parameters using evolutionary models. Assuming the evolutionary-based parameters are more robust, our spectroscopically inferred parameters from BT-Settl exhibit two types of systematic behavior for objects near the M-L spectral type boundary. Several objects are clustered around T eff ≈ 1800 K and $\mathrm{log}g\approx 5.5$ dex, implying impossibly large masses (150-1400 M Jup), while others are clustered around T eff ≳ 3000 K and $\mathrm{log}g\lesssim 3.0$ dex, implying unphysically low masses and unreasonably young ages. We find the fitted BT-Settl model spectra tend to overpredict the peak J- and H-band flux for objects located near the M-L boundary, suggesting the dust content included in the model atmospheres is insufficient to match the observations. By adding an interstellar medium-like reddening law to the BT-Settl model spectra, we find the fits between models and observed spectra are greatly improved, with the largest reddening coefficients occurring at the M-L transition. This work delivers a systematic examination of the BT-Settl model atmospheres and constitutes the largest spectral analysis of benchmark late-M- and L-type brown dwarfs to date.

Keywords: M dwarf stars, Brown dwarfs, Exoplanet atmospheres, L dwarfs, Stellar atmospheres
Line Profiles of Forbidden Emission Lines and What They Can Tell Us About Protoplanetary Disk Winds. Emission in forbidden lines of oxygen, neon, and other species are commonly used to trace winds from protoplanetary disks. Using Cloudy, we calculate such emission for parametrized wind models of the magnetothermal type, following Bai et al. These models share characteristics with both photoevaporative and magnetocentrifugal winds, which can be regarded as end members, and are favored by recent theoretical research. Both broad and narrow low-velocity components of the lines can be produced with plausible wind parameters, something that traditional wind models have difficulty with. Line luminosities, blueshifts, and widths, as well as trends of these with accretion luminosity and disk inclination, are in general accordance with observations.

Keywords: Atomic spectroscopy, Protoplanetary disks
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Discovery of an Extremely Dense and Compact Object Embedded in the Prestellar Core G208.68-19.92-N2. The internal structure of the prestellar core G208.68-19.02-N2 (G208-N2) in the Orion Molecular Cloud 3 (OMC-3) region has been studied with the Atacama Large Millimeter/submillimeter Array. The dust continuum emission revealed a filamentary structure with a length of ~5000 au and an average H2 volume density of ~6 × 107 cm-3. At the tip of this filamentary structure, there is a compact object, which we call a nucleus, with a radius of ~150-200 au and a mass of ~0.1 M ⊙. The nucleus has a central density of ~2 × 109 cm-3 with a radial density profile of r -1.87±0.11. The density scaling of the nucleus is ~3.7 times higher than that of the singular isothermal sphere (SIS). This as well as the very low virial parameter of 0.39 suggests that the gravity is dominant over the pressure everywhere in the nucleus. However, there is no sign of CO outflow localized to this nucleus. The filamentary structure is traced by the N2D+ 3-2 emission, but not by the C18O 2-1 emission, implying the significant CO depletion due to high density and cold temperature. Toward the nucleus, the N2D+ also shows the signature of depletion. This could imply either the depletion of the parent molecule, N2, or the presence of the embedded very-low luminosity central source that could sublimate the CO in the very small area. The nucleus in G208-N2 is considered to be a prestellar core on the verge of first hydrostatic core (FHSC) formation or a candidate for the FHSC.

Keywords: Early stellar evolution, Star forming regions, Molecular clouds, Astrochemistry, Star formation, Collapsing clouds
Magnetic Fields in Giant Filaments Probed by the Velocity Gradient Technique: Regular Magnetic Field Interrupted by Magnetization Gaps. We study the magnetic field structures in six giant filaments associated with the spiral arms of the Milky Way by applying the velocity gradient technique (VGT) to the 13CO spectroscopic data from the GRS, FUGIN, and SEDIGSM surveys. Unlike dust-polarized emission, the VGT allows us to separate the foreground and background using the velocity information, from which the orientation of the magnetic field can be reliably determined. We find that in most cases the magnetic fields stay aligned with the filament bodies, which are parallel to the disk midplane. Among these, G29, G47, and G51 exhibit smooth magnetic fields, and G24, G339, and G349 exhibit discontinuities. The fact that most filaments have magnetic fields that stay aligned with the Galactic disk midplane suggests that Galactic shear may be responsible for shaping the filaments. The fact that the magnetic field can stay regular at the resolution of our analysis (≲10 pc), where the turbulence crossing time is short compared to the shear time, suggests that turbulent motion cannot effectively disrupt the regular orientation of the magnetic field. The discontinuities found in some filaments can be caused by processes including filament reassembly, gravitational collapse, and stellar feedback.

Keywords: Interstellar magnetic fields, Interstellar dynamics, Interstellar medium
Magnetic Hump Associated with Electron Vortex at Dipolarization Front. As the plasma boundary between two distinct plasma populations, dipolarization fronts (DFs) host abundant kinetic-scale substructures that change their normal directions and thus cause their deformation. However, studies on such deformation caused by an electron vortex have been lacking. Here, we present novel observations of a subion-scale magnetic hump (MHu) associated with an oblique electron vortex at a DF through strengthening three components of the magnetic field. A radial electric field in the MHu, showing bipolar variation, is also associated with the electron vortex as it is mainly ascribed to the electron convection term. There is apparent energy conversion ( $\overrightarrow{J}\cdot \overrightarrow{E}$ ~-0.3 nw m-3) from the particles to the electromagnetic field in the MHu's leading part, which is accompanied by inflow and outflow of electromagnetic energy (nonzero ${\rm{\nabla }}\cdot \overrightarrow{S}$ ). The other regions of the DF host opposite energy conversion ( $\overrightarrow{J}\cdot \overrightarrow{E}$ &gt; 0). Broadband parallel electrostatic waves are also observed in the MHu. Our study provides insights into the kinetic-scale processes at DFs.

Keywords: Space plasmas, Space weather, Planetary magnetospheres
A Search for Faint Resolved Galaxies Beyond the Milky Way in DES Year 6: A New Faint, Diffuse Dwarf Satellite of NGC 55. We report results from a systematic wide-area search for faint dwarf galaxies at heliocentric distances from 0.3 to 2 Mpc using the full 6 yr of data from the Dark Energy Survey (DES). Unlike previous searches over the DES data, this search specifically targeted a field population of faint galaxies located beyond the Milky Way virial radius. We derive our detection efficiency for faint, resolved dwarf galaxies in the Local Volume with a set of synthetic galaxies and expect our search to be complete to M  V  ∼ (‑7, ‑10) mag for galaxies at D = (0.3, 2.0) Mpc. We find no new field dwarfs in the DES footprint, but we report the discovery of one high-significance candidate dwarf galaxy at a distance of ${2.2}_{-0.12}^{+0.05}\,\mathrm{Mpc}$ , a potential satellite of the Local Volume galaxy NGC 55, separated by 47' (physical separation as small as 30 kpc). We estimate this dwarf galaxy to have an absolute V-band magnitude of $-{8.0}_{-0.3}^{+0.5}\,\mathrm{mag}$ and an azimuthally averaged physical half-light radius of ${2.2}_{-0.4}^{+0.5}\,\mathrm{kpc}$ , making this one of the lowest surface brightness galaxies ever found with $\mu =32.3\,\mathrm{mag}\,{\mathrm{arcsec}}^{-2}$ . This is the largest, most diffuse galaxy known at this luminosity, suggesting possible tidal interactions with its host.

Keywords: Local Group, Dwarf galaxies, Low surface brightness galaxies
Dynamical Stellar Mass-to-light Ratio Gradients: Evidence for Very Centrally Concentrated IMF Variations in ETGs?. Evidence from different probes of the stellar initial mass function (IMF) of massive early-type galaxies (ETGs) has repeatedly converged on IMFs more bottom heavy than in the Milky Way (MW). This consensus has come under scrutiny due to often contradictory results from different methods on the level of individual galaxies. In particular, a number of strong lensing probes are ostensibly incompatible with a non-MW IMF. Radial gradients of the IMF-related to gradients of the stellar mass-to-light ratio ϒ-can potentially resolve this issue. We construct Schwarzschild models allowing for ϒ-gradients in seven massive ETGs with MUSE and SINFONI observations. We find dynamical evidence that ϒ increases toward the center for all ETGs. The gradients are confined to subkiloparsec scales. Our results suggest that constant-ϒ models may overestimate the stellar mass of galaxies by up to a factor of 1.5. For all except one galaxy, we find a radius where the total dynamical mass has a minimum. This minimum places the strongest constraints on the IMF outside the center and appears at roughly 1 kpc. We consider the IMF at this radius characteristic for the main body of each ETG. In terms of the IMF mass-normalization α relative to a Kroupa IMF, we find on average an MW-like IMF &lt;α main&gt; = 1.03 ± 0.19. In the centers, we find concentrated regions with increased mass normalizations that are less extreme than previous studies suggested, but still point to a Salpeter-like IMF, &lt;α cen&gt; = 1.54 ± 0.15.

Keywords: Supermassive black holes, Galaxy dynamics, Stellar mass functions, Mass-to-light ratio, Galaxy kinematics, Galaxy evolution, Early-type galaxies
Recurrently Propagating Intensity Disturbances along Polar Plumes Observed in White Light and Extreme Ultraviolet. We study properties of intensity disturbances along polar coronal rays that are associated with plumes below. For this, we draw azimuth–time images of extreme ultraviolet (EUV) emission of 171 Å band observed by the SDO/AIA and white light (WL) observed by the SOHO/LASCO C2 in 2020 July. From the azimuth–time image, we define two tracks in which the EUV intensities were recurrently enhanced during two weeks. The two EUV tracks are rooted at 78.°8 and 81.°4 latitudes, but their projected azimuth angles are changed with time as the Sun rotates. Coherent WL tracks at different altitudes are determined by scaling the azimuth angles of the EUV tracks, accounting for the effect of inclination of coronal rays. From this, we construct time–distance images of WL intensities along WL tracks, whose projected azimuth angle changes along time and altitude, but the intensities are correlated with the EUV intensities measured below. The time–distance images of WL show repeated and inclined intensity features. The propagation speeds in the altitude range 2.3–6 solar radii are calculated to be 159 ± 8 km s‑1 and 300 ± 24 km s‑1. The EUV and WL intensities are found to be coherent at 1–2 day periods. It is also found that dynamic burst events along the EUV track are responsible for the enhanced emission. We conclude that the variation of the WL intensity along the polar coronal rays is related with the evolution of the EUV intensity below.

Keywords: Solar wind, The Sun, Solar coronal plumes
Reproduction Experiments of Radial Pyroxene Chondrules Using a Gas-jet Levitation System under Reduced Conditions. Reproduction experiments of radial pyroxene (RP) chondrules were carried out using an Ar-H2 or Ar gas-jet levitation system in a reducing atmosphere in order to simulate chondrule formation in the protoplanetary disk. The experiments reproduced RP-chondrule textures, consisting of sets of thin pyroxene crystals and mesostasis glass between crystals. However, iron partition coefficients between pyroxene and glassy mesostasis (DFe =Fe mol%pyroxene/Fe mol%mesostasis) in natural RP chondrules were much higher than that in the experimentally reproduced RP chondrules. The high DFe in natural RP chondrules suggests that iron was removed from the mesostasis melt at high temperatures after the growth of pyroxene crystals. We found that many small iron-metal inclusions had formed in the mesostasis glass, indicating that FeO in the high-temperature melt of mesostasis was reduced to metallic iron, and iron in the mesostasis diffused into the newly formed metal inclusions. The formation of the iron-metal inclusions in the mesostasis was reproduced by our experiments in a reducing atmosphere, confirming that DFe in natural RP chondrules increased after the growth of RP crystals. Therefore, the DFe of RP chondrules can be an indicator to constrain cooling rates and redox states during chondrule formation.

Keywords: Experimental techniques, Chondrules, Protoplanetary disks, Chondrites
A Statistical Study of Soft X-Ray Flares on Solar-type Stars. The statistical characteristics of stellar flares at optical bands have received extensive study, but they remain to be studied at soft X-ray bands, in particular for solar-type stars. Here, we present a statistical study of soft X-ray flares on solar-type stars, which can help in understanding the multiwavelength behaviors of stellar flares. We mainly use Chandra Source Catalog Release 2.0, which includes a number of flaring stars with denoted variability, and Gaia Data Release 3, which includes the necessary information for classifying stars. We also develop a set of methods for identifying and classifying stellar soft X-ray flares and estimating their properties. A detailed statistical investigation of 129 flare samples on 103 nearby solar-type stars as selected yields the following main results. (1) The flare energy emitted at the soft X-ray band in our sample ranges from ~1033 to ~1037 erg, and the majority of them are superflares, with the most energetic one having energy of ${6.0}_{-4.7}^{+3.2}\times {10}^{37}\ \mathrm{erg}$ . (2) The flare duration is related to its energy as formulated by ${T}_{\mathrm{duration},\mathrm{SXR}}\propto {E}_{\mathrm{flare},\mathrm{SXR}}^{\ 0.201\pm 0.024}$ , which is different from those derived at optical and near-IR bands, indicating distinct radiation mechanisms at different bands. (3) The frequency distribution of stellar flares as a function of energy is formulated as ${{dN}}_{\mathrm{flare}}/{{dE}}_{\mathrm{flare},\mathrm{SXR}}\propto {E}_{\mathrm{flare},\mathrm{SXR}}^{\ -1.77}$ , which is similar to the results found at other bands and on other types of stars, indicating that the energy emitted at the soft X-ray band could be a constant fraction of the full-band bolometric energy.

Keywords: Stellar x-ray flares, Stellar magnetic fields, Flare stars, Stellar activity, Stellar astronomy, Stellar physics, Stellar atmospheres, Stellar flares, Magnetic fields, X-ray stars
The Effective Field Theory of Large-scale Structures of a Fuzzy Dark Matter Universe. Ultralight scalar fields and their noninteracting class, i.e., the so-called fuzzy dark matter (FDM), are dark matter candidates introduced to solve the small-scale problems of the standard cold dark matter. In this paper, we investigate whether the physics of FDM, particularly the quantum pressure that leads to the suppression of structure formation on small scales, could leave significant imprints on the large-scale statistics of matter fluctuations. For this purpose, we utilize the Effective Field Theory of Large Scale Structures (EFT of LSS), wherein small-scale physics is integrated and represented on large scales by only a set of free parameters. These parameters can be determined by fitting them into the cosmological simulations. By fitting the EFT predictions to the simulation data, we determine the value of the speed of sound as a quantitative measure of how UV physics affects large-scale perturbation. We use the Gadget-2 code to study the evolution of 5123 particles in a box with a side length 250 h -1 Mpc. We exploit the suppressed FDM initial power for the FDM universe and perform N-body simulation sufficient to produce accurate-enough for our purpose-results on large scales. In particular, we perform three FDM simulations with different masses and compare their sound speed with the standard cold dark matter (CDM) simulation. We found no difference between the FDM and CDM sound speeds beyond the confidence intervals. However, a consistently increasing trend can be seen in the sound speed for lower masses. This result suggests further investigations using higher-resolution simulations.

Keywords: Cosmology, Dark matter distribution, Dark matter, Large-scale structure of the universe
First JWST Observations of JAGB Stars in the SN Ia Host Galaxies: NGC 7250, NGC 4536, NGC 3972. The J-region Asymptotic Giant Branch (JAGB) method is a standard candle that leverages the constant luminosities of color-selected, carbon-rich AGB stars, measured in the near-infrared at 1.2 μm. The Chicago-Carnegie Hubble Program has obtained JWST imaging of the SN Ia host galaxies NGC 7250, NGC 4536, and NGC 3972. With these observations, the JAGB method can be studied for the first time using JWST. Lee et al. demonstrated the JAGB magnitude is optimally measured in the outer disks of galaxies, because in the inner regions the JAGB magnitude can vary significantly due to a confluence of reddening, blending, and crowding effects. However, determining where the "outer disk" lies can be subjective. Therefore, we introduce a novel method for systematically selecting the outer disk. In a given galaxy, the JAGB magnitude is first separately measured in concentric regions, and the "outer disk" is then defined as the first radial bin where the JAGB magnitude stabilizes to a few hundredths of a magnitude. After successfully employing this method in our JWST galaxy sample, we find the JAGB stars are well segregated from other stellar populations in color-magnitude space, and have observed dispersions about their individual F115W modes of σ N7250 = 0.32 mag, σ N4536 = 0.34 mag, and σ N3972 = 0.35 mag. These measured dispersions are similar to the scatter measured for the JAGB stars in the LMC using 2MASS data (σ = 0.33 mag). In conclusion, the JAGB stars as observed with JWST clearly demonstrate their considerable power both as high-precision extragalactic distance indicators and as SN Ia supernova calibrators.

Keywords: Galaxy distances, Carbon stars, Observational cosmology, Distance indicators, Asymptotic giant branch stars, James Webb Space Telescope
Are Radio Minihalos Confined by Cold Fronts in Galaxy Clusters? Minihalos and Large-scale Sloshing in A3444 and MS 1455.0+2232. We present radio and X-ray studies of A3444 and MS1455.0+2232, two galaxy clusters with radio minihalos in their cool cores. A3444 is imaged using the Giant Metrewave Radio Telescope (GMRT) at 333, 607, and 1300 MHz and the Very Large Array at 1435 MHz. Most of the minihalo is contained within r &lt; 120 kpc, but a fainter extension, stretching out to 380 kpc southwest of the center, is detected at 607 MHz. Using Chandra, we detect four X-ray sloshing cold fronts: three in the cool core at r = 60, 120, and 230 kpc, and a fourth one at r = 400 kpc-in the region of the southwestern radio extension-suggesting that the intracluster medium (ICM) is sloshing on a cluster-wide scale. The radio emission is contained within the envelope defined by these fronts. We also analyzed archival 383 MHz GMRT and Chandra observations of MS 1455.0+2232, which exhibits a known minihalo with its bright part delineated by cold fronts inside the cool core, but with a faint extension beyond the core. Similarly to A3444, we find a cold front at r ~ 425 kpc, containing the radio emission. Thus the entire diffuse radio emission seen in these clusters appears to be related to large-scale sloshing of the ICM. The radio spectrum of the A3444 minihalo is a power law with a steep index α = 1.0 ± 0.1. The spectrum steepens with increasing distance from the center, as expected if the minihalo originates from reacceleration of relativistic particles by the sloshing-induced turbulence in the ICM.

Keywords: Galaxy clusters, Extragalactic astronomy, Intracluster medium, Radio astronomy
Jet Reorientation in Central Galaxies of Clusters and Groups: Insights from VLBA and Chandra Data. Recent observations of galaxy clusters and groups with misalignments between their central active galactic nucleus jets and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet-bubble connection in cooling cores, and the processes responsible for jet realignment. To investigate the frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and groups. Using Very Long Baseline Array radio data, we measure the parsec-scale position angle of the jets, and compare it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample and selected subsets, we consistently find that there is a 30%-38% chance to find a misalignment larger than ΔΨ = 45° when observing a cluster/group with a detected jet and at least one cavity. We determine that projection may account for an apparently large ΔΨ only in a fraction of objects (~35%), and given that gas dynamical disturbances (such as sloshing) are found in both aligned and misaligned systems, we exclude environmental perturbation as the main driver of cavity-jet misalignment. Moreover, we find that large misalignments (up to ~90°) are favored over smaller ones (45° ≤ ΔΨ ≤ 70°), and that the change in jet direction can occur on timescales between one and a few tens of Myr. We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we discuss several engine-based mechanisms that may cause these dramatic changes.

Keywords: Galaxy clusters, Supermassive black holes, Relativistic jets, Radio galaxies, Galaxy groups, Intracluster medium