Sazuna/UAT_keywords huggingface dataset:
ALMA High-resolution Observation for the Transitional Disk Around IRAS 04125+2902. Recently, the youngest transiting planet was discovered around the T Tauri star, IRAS 04125+2902, in the Taurus-Auriga star-forming region. This system is crucial for understanding the early stages of planet formation. We used Atacama Large Millimeter/submillimeter Array Band 6 data to investigate the IRAS 04125+2902 system in detail. The dust continuum emission reveals a ring-gap transitional disk structure with an inclination of 35.6 .° . In addition, two-dimensional super-resolution imaging based on Sparse Modeling and the one-dimensional modeling of disk brightness distribution suggest the existence of an inner emission, which may be attributed to an inner disk, although free─free emission from the central star is not ruled out. Furthermore, we identified the 12CO J = 2─1 emission, and the dynamical mass of the central star is estimated to be 0.7─1.0 M⊙. The asymmetry of the dust ring and the velocity distortion around the central star are, if at all, weak, suggesting that the inner disk, if it exists, is not highly inclined with respect to the outer disk. Radiative transfer calculations of dust continuum emission suggest that the inner and the outer disks may be misaligned by ∼10°, which may be confirmed in future observations with higher resolution and sensitivity. Our results suggest that IRAS 04125+2902 is a dynamically complex system, where the binary orbit, outer disk, inner disk, and planetary orbit are mutually misaligned, providing insight into the early orbital evolution of young systems.

Keywords: Exoplanet migration, Radio interferometry, Protoplanetary disks
SHELLQs-JWST Unveils the Host Galaxies of 12 Quasars at z &gt; 6. The advent of the James Webb Space Telescope (JWST) has opened new horizons in the study of quasar host galaxies during the reionization epoch (z &gt; 6). Building upon our previous initial measurements of stellar light from two quasar host galaxies at these redshifts, we now report the detection of the stellar light from the full Cycle 1 sample of 12 distant moderate-luminosity quasar (M1450 &gt; −24 mag) host galaxies at z &gt; 6 from the Hyper Suprime-Cam Subaru Strategic Program. Using JWST/NIRCam observations at 1.5 and 3.6 μm combined with 2D image decomposition analysis, we successfully detect the host galaxies in 11 of the 12 targets, underscoring the high detection rates achievable with moderate-luminosity quasars. Based on two-band photometry and spectral energy distribution fitting, we find that our host galaxies are massive, with log M*/M⊙ = 9.5─11.0. The effective radii range from 0.6 to 3.2 kpc, comparable to the sizes of inactive galaxies with similar masses at z ∼ 6 as measured with imaging from COSMOS-Web. Intriguingly, the two quasar hosts with post-starburst features, which reside at the high-mass end of our sample and exhibit relatively compact morphologies, have similar size and stellar mass surface densities to quiescent galaxies at z ∼ 4─5. These findings suggest that the so-called galaxy compaction scenario is already in place at the reionization epoch, in which gas inflows during starburst phases drive centrally concentrated star formation followed by rapid quenching, bridging the structural transition of massive galaxies from relatively extended star-forming disks to compact quiescent systems.

Keywords: AGN host galaxies, Early universe, Quasars
A Comprehensive Characterization of Galaxy-cool CGM Connections at z &lt; 0.4 with DESI Year 1 Data. We investigate the relationships between the cool circumgalactic medium (CGM), traced by Ca II absorption lines, and galaxy properties at z &lt; 0.4 using ∼900,000 galaxy─quasar pairs within 200 kpc from the Year 1 data of the Dark Energy Spectroscopic Instrument (DESI). This large data set enables us to obtain composite spectra with sensitivity reaching to the mÅ level and to explore the Ca II absorption as a function of stellar mass, star formation rate (SFR), redshift, and galaxy types, including active galactic nuclei (AGNs). Our results show a positive correlation between the absorption strength and stellar mass of star-forming galaxies with  &lt;W0CaII&gt;∝M∗0.5  over 3 orders of magnitude in stellar mass from ∼108 to 1011 M⊙, while such a mass dependence is weaker for quiescent galaxies. At a fixed mass, Ca II absorption is stronger around star-forming galaxies than quiescent ones especially within impact parameters &lt;30 kpc. Among star-forming galaxies, the Ca II absorption further correlates with SFR, following ∝SFR0.3. However, in contrast to the results at higher redshifts, stronger absorption is not preferentially observed along the minor axis of star-forming galaxies, indicating a possible redshift evolution of CGM dynamics resulting from galactic feedback. Moreover, no significant difference between the properties of the cool gas around AGNs and galaxies is detected. Finally, we measure the absorption profiles with respect to the virial radius of dark matter halos and show that the total Ca II mass in the CGM is comparable to the Ca mass in the ISM of galaxies.

Keywords: Extragalactic astronomy, Spectroscopy, Circumgalactic medium
The Cusp─Halo Relation. Simulations have established that each halo of collisionless dark matter is expected to contain a ρ = Ar−1.5 density cusp at its center. This prompt cusp is a relic of the halo's earliest moments and has a mass comparable to the cutoff scale in the spectrum of initial density perturbations. In this work, we provide a framework to predict, for each halo, the coefficient A of its central cusp. We also present a "cusp─Navarro─Frenk─White (cusp─NFW)" functional form that accurately describes the density profile of a halo with a prompt cusp at its center. Accurate characterization of each halo's central cusp is of particular importance in the study of warm dark matter models, for which the spectral cutoff is on an astrophysically relevant mass scale. To facilitate easy incorporation of prompt cusps into any halo modeling approach, we provide a code package that implements the cusp─halo relation and the cusp─NFW density profile.

Keywords: Warm dark matter, Galaxy dark matter halos, Dark matter, N-body simulations
Two Decades of Dust Evolution in SN 2005af through JWST, Spitzer, and Chemical Modeling. The evolution of dust in core-collapse supernovae (SNe), in general, is poorly constrained owing to a lack of infrared observations a few years after explosion. Most theories of dust formation in SNe heavily rely only on SN 1987A. In the last two years, the James Webb Space Telescope (JWST) has enabled us to probe the dust evolution in decades-old SNe, such as SN 2004et, SN 2005ip, and SN 1980K. In this paper, we present two decades of dust evolution in SN 2005af, combining early-time infrared observations with the Spitzer Space Telescope and recent detections by the JWST. We have used a chemical kinetic model of dust synthesis in SN ejecta to develop a template of dust evolution in SN 2005af. Moreover, using this approach, for the first time, we have separately quantified the dust formed in the pre-explosion wind that survived after the explosion and the dust formed in the metal-rich SN ejecta post-explosion. We report that in SN 2005af, predominantly carbon-rich dust formed in the ejecta, with a total mass of at least 0.02 M⊙. In the circumstellar medium, the surviving oxygen-rich dust amounts to about (3─6) × 10−3 M⊙, yielding a total dust mass of at least 0.025 M⊙.

Keywords: Core-collapse supernovae, Dust formation, James Webb Space Telescope, Circumstellar dust, Infrared photometry
Improving Solar Flare Nowcasting with the Hot Onset Precursor Event Technique. This study investigates the statistical behavior of plasma properties during hot onset precursor events (HOPEs) of solar flares and evaluates their potential for improving flare nowcasting. Two data sets are analyzed: (a) new soft X-ray (SXR) spectra of 25 flares (C2.6─M1.0) obtained from the Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) and (b) SXR irradiance data from 137 flares (C5.0─X7.1) recorded by the X-Ray Sensor on the Geostationary Operational Environmental Satellite (GOES-XRS). Plasma temperature, emission measure (EM), and low first ionization potential (e.g., Mg, Si, Fe) elemental abundance factors (AFs) are derived from DAXSS using Astrophysical Plasma Emission Code model fitting. Isothermal plasma temperature and EM are derived from GOES-XRS using the XRS-A/XRS-B ratio method. Results indicate that the HOPE phase exhibits elevated temperatures (10─15 MK) and an order-of-magnitude increase in EM before the impulsive phase. Elemental AFs show a transition from coronal to photospheric values as the flare progresses. Using GOES-XRS data, we develop an improved nowcasting algorithm that detects flares utilizing HOPE signatures. The algorithm is tested across three categories of flares (C5.0─M1.0, M1.0─X1.0, and X1.0+), consistently predicting flare alerts 5─15 minutes ahead of the flare peak. We also explore the possibility of approximate flare magnitude prediction by calculating the correlation between onset parameters and flare peak magnitude. This HOPE-based system shows potential for earlier warnings than current NOAA R3 alerts, which could be useful for high-frequency communication systems operators and targeted flare observation campaigns.

Keywords: Solar flare spectra, Solar x-ray emission, Solar abundances, Solar physics, Solar corona, Solar x-ray flares
TESS Subgiant and Lower-red-giant Asteroseismology in the Continuous Viewing Zones. Asteroseismology, the study of stellar oscillations, and stellar modeling both offer profound insights into the fundamental properties and evolution of stars. With pySYD, a new open-source Python package, we were able to constrain the asteroseismic global parameters, νmax and ∆ν, for 82 solar-like oscillating subgiant and lower red giant stars, filling in the region between the Kepler dwarfs and giants. Using asteroseismic scaling relations, we were able to compute seismic masses, radii, and surface gravities for our entire sample with average errors of 0.21 M⊙, 0.27 R⊙, and 0.06 dex, respectively. Using four stellar-modeling grids we determine and compare stellar ages for our sample. We find that our age distribution from stellar modeling is consistent with other local star samples. We find small consistent offsets from model predictions across our regime, but offsets were worse at higher gravities (log(g) ≥ 3.5 dex), suggesting the need for better calibration. Finally, we discuss our sample in the context of galactic archaeology and show how ages like these could be used to identify and study binary system evolution and galactic evolution in the future. All in all, we show that asteroseismology can be successfully performed with TESS data and can continue to make an impact on our understanding of stellar physics and galactic archaeology.

Keywords: Computational astronomy, Light curves, Stellar astronomy, Stellar physics, Stellar oscillations, Asteroseismology
GRMHD Study of Accretion onto Time-like Naked Singularities. Naked singularities (NkSs) are solutions to the Einstein field equations that violate the cosmic censorship conjecture. Recent studies indicate that these objects may serve as compelling mimickers of black hole (BH) shadows. In this work, we investigate the accretion dynamics of selected time-like NkSs using general relativistic magnetohydrodynamic simulations. Our objective is to determine whether NkSs exhibit distinct signatures compared to BHs. We find that, unlike BHs, NkSs exhibit a centrifugal barrier that prevents direct accretion of rotating matter onto the NkSs. Despite reduced magnetization in the funnel region, these objects are capable of generating jet powers comparable to those observed in BHs. Additionally, we observe that accreting matter releases gravitational energy as it is driven toward the NkSs, powering the strong outflow via local fluid pressure gradient or magnetic pressure forces.

Keywords: Accretion, Black hole physics, Hydrodynamical simulations, Naked singularities, Gravitation, Magnetohydrodynamical simulations
Dynamical Mechanism of Episodic Gas Accretion to the Central Region of Spiral Galaxies. We performed N-body/smoothed particle hydrodynamics simulations of isolated spiral galaxies with various bulge-to-disk mass ratios (Mbulge/Mdisk) from 0.02 to 0.2 to investigate mass transport from galactic scales (10 kpc) down to circumnuclear disk scales (≲100 pc). Our analysis revealed these main findings: (1) Gravitational torque from stellar spiral arms causes gas accretion with ∼1 M⊙ yr−1 along the gas spiral arms from a few kiloparsecs to a few 100 pc scale. The density of accreting gas is a few 100 cm−3, comparable to the gas arms. The pressure gradient force is over an order of magnitude weaker than the stellar gravitational torque. (2) Gravitational torque from barred structure causes episodic gas clump accretion with ∼1 M⊙ yr−1 on timescales of 10 Myr from the kiloparsec to a few 100 pc scale. The densities of these clumps exceed 700 cm−3, and this accretion occurs along elliptical orbits with a delayed phase relative to the bar potential. (3) Episodic gas clumpy accretion is important for galactic center instability, confirmed by Mbulge/Mdisk = 0.02 but not by Mbulge/Mdisk = 0.1 and 0.2. This difference occurs because in the bulge-dominated potentials, bar instability is suppressed, and rapid gas clump accretion does not occur. These findings suggest that gas clump accretion events driven by bars could be a source of high-density gas to the galactic center of the spiral galaxy, potentially promoting temporary activity in the galactic center.

Keywords: Barred spiral galaxies, Active galactic nuclei, Galaxy evolution, Spiral galaxies
Extreme-ultraviolet Wave and Quasiperiodic Pulsations during an Eruptive M-class Flare. In this paper, we report multiwavelength and multipoint observations of the prominence eruption originating from active region 11163, which generated an M3.5 class flare and a coronal mass ejection (CME) on 2011 February 24. The prominence lifts off and propagates nonradially in the southeast direction. Using the revised cone model, we carry out three-dimensional reconstructions of the ice-cream-like prominence. It is found that the latitudinal inclination angle decreases from ∼60° to ∼37°, indicating that the prominence tends to propagate more radially. The longitudinal inclination angle almost keeps constant (−6°). The highly inclined prominence eruption and the related CME drive an extreme-ultraviolet (EUV) wave, which propagates southward at speeds of ∼381.60 and ∼398.59 km s−1 observed in 193 and 304 Å, respectively. The M3.5 class flare presents quasiperiodic pulsations (QPPs) in soft X-ray, hard X-ray, EUV, and radio wavelengths with periods of 80−120 s. Contemporary with the flare QPPs, a thin current sheet and multiple plasmoids are observed following the eruptive prominence. Combining with the appearance of drifting pulsation structure, the QPPs are most probably generated by quasiperiodic magnetic reconnection and particle accelerations as a result of plasmoids in the current sheet.

Keywords: Solar oscillations, Solar flares, Solar prominences
Kinetic Simulations of Particle Acceleration in Relativistic Perpendicular Electron─Positron Shocks with Proton Admixture. Particle acceleration in relativistic shocks of electron─positron plasmas with proton admixture is investigated through two-dimensional particle-in-cell simulations. The upstream plasma, with a bulk Lorentz factor of 10 and a magnetization parameter of 0.02, includes a small fraction of protons (∼5% by number). A relativistic perpendicular shock is formed by reflecting the flow off a conducting wall. The shock structure, electromagnetic fields, and particle energy spectra are analyzed. The particle density and the magnetic field have fluctuations. In the far-downstream region of the shock, positrons are accelerated to energies comparable to protons and develop a hard nonthermal component with a spectral index of ∼2 in their energy spectrum, while electrons remain confined to lower energies. This asymmetry is attributed to the polarization properties of proton-driven electromagnetic waves, which favor positron acceleration. The results highlight the importance of plasma composition in shaping particle acceleration and nonthermal emission in relativistic shocks. These findings provide new insights into the microphysics of particle acceleration in astrophysical sources containing relativistic shocks.

Keywords: Shocks, Plasma astrophysics, High energy astrophysics
Simulating the Ring-shaped Line-of-sight Flows in Prominence-cavity Systems. Line-of-sight oriented flows with several red and blue Doppler-shifted rings in coronal cavities have been observed by the Coronal Multi-channel Polarimeter (CoMP) but rarely explained. In this paper, we perform pseudo-3D simulations with a Titov─Démoulin-modified magnetic flux rope (MFR) to study the corresponding flows in coronal cavities by forward modeling. Two types of field-aligned flows are found. The first type is converging flows, which are located in the magnetic field lines near the MFR axis, converging toward the magnetic dips and driven by the filament condensation, corresponding to the inner flows. The second type is unidirectional flows, which are located in the magnetic field lines near the MFR boundary, flowing from one footpoint to the other, and are driven by the asymmetric heating, corresponding to the outer flows. These inner and outer flows naturally form a nested structure with a velocity of several km s−1, leading to the formation of multiple rings observed in the cavity view. Synthetic Doppler images indicate two to four rings in our simulations, which is consistent with most of the observational situations by CoMP.

Keywords: Solar prominences, Solar magnetic fields, Magnetohydrodynamical simulations
Systematic Nonthermal Velocity Increase Preceding Soft X-Ray Flare Onset: A Large-scale Hinode/EIS Study. Nonthermal velocities, derived from spectral line broadening, can provide crucial insights into plasma dynamics before and during solar flares. To systematically study the preflare phase, we constructed a Hinode/Extreme-ultraviolet Imaging Spectrometer flare catalog of 1449 flares from 2011 to 2024. This enabled a large-scale analysis of flare loop footpoint nonthermal velocity evolution across different flare magnitudes (C, M, X-classes). Analyzing Fe VIII─Fe XXIV emission lines formed at log(T/K) ∼ 5.7─7.3 with piecewise linear fits in the preflare period, we find that nonthermal velocities consistently increase 4─25 minutes before Geostationary Operational Environmental Satellite (GOES) soft X-ray start in C and M-class flares. Onset timing patterns vary with flare magnitude: smaller flares show temperature-dependent progression, while larger flares exhibit more compressed, near-simultaneous onsets across temperatures. While our limited X-class sample (N = 18) also show onset before GOES, larger statistics are needed to confirm its behavior. M-class flares show a systematic precursor nonthermal velocity onset ∼30─60 minutes before GOES peak. In a subset of M-class flares (2011─2018), coronal-mass-ejection (CME)-associated events show earlier and more uniform precursor onsets (45─74 minutes before peak) than non-CME events, of which only some lines display a precursor, suggesting a strong link between extended preflare nonthermal broadening and successful eruptions. This large scale study establishes preflare nonthermal velocity increase at footpoints as a common precursor observable before any X-ray signature.

Keywords: Solar atmosphere, Solar flares, Solar energetic particles, Solar physics, Solar corona, Solar coronal mass ejections
Periodic Variations in Visible Light Brightness as Tracers of Fine Coronal Structures. The quiescent or dynamic nature of fine-scale raylike features in the Sun corona, observed in visible light, is still an open question. Here, we show that most of the daily and hourly periodic variations in visible light brightness of the high corona (up to 15 R⊙) are aligned to the tip of streamers and are consistent with the periodicity of plasma release from simulations of tearing-induced magnetic reconnection at the heliospheric current sheet. The areas in which we detect periodicities can be used as tracers of nonquiescent fine coronal rays. This also allows their distinction from coronal rays more likely to be real quiescent features or associated with smaller and/or faster unresolved brightness variations. In the low- and middle-corona (down to 1.4 R⊙) similar brightness variations are observed along loop-like and cusp-like features marking boundaries of streamers, which then connect to radial features in the high corona. This suggests the presence of additional mechanisms in the low- and middle-corona periodically releasing density structures in the solar wind. The periodicity distributions show a solar cycle modulation with shorter periods (smaller structures) during solar maximum. Periodicities are observed within streamers during solar minimum but are visible at all latitudes, even extending radially from the poles, during solar maximum.

Keywords: Solar cycle, Astronomical techniques, Quiet sun, Solar corona
The Aromatic Infrared Bands around the Wolf─Rayet Binary WR 140 Revealed by JWST. We have analyzed the aromatic infrared bands (AIBs) in the 6─11.2 μm range around the Wolf─Rayet (WR) binary WR 140 (d = 1.64 kpc) obtained with the James Webb Space Telescope Mid-Infrared Instrument Medium-Resolution Spectrometer (MRS). In WR 140's circumstellar environment, we have detected AIBs at 6 and 7.7 μm, which are attributed to C─C stretching modes. These features have been detected in the innermost dust shell (Shell 1; ∼2100 au from WR 140), the subsequent dust shell (Shell 2; ∼5200 au), and "off-shell" regions in the MRS coverage. The 11.2 μm AIB, which is associated with the C─H out-of-plane bending mode, has been tentatively detected in Shell 2 and the surrounding off-shell positions around Shell 2. We compared the AIB features from WR 140 to spectra of established AIB feature classes A, B, C, and D. The detected features around WR 140 do not agree with these established classes. The peak wavelengths and full width half maxima of the 6 and 7.7 μm features are, however, consistent with those of R Coronae Borealis stars with hydrogen-poor conditions. We discuss a possible structure of carbonaceous compounds and environments where they form around WR 140. It is proposed that hydrogen-poor carbonaceous compounds initially originate from the carbon-rich WR wind, and the hydrogen-rich stellar wind from the companion O star may provide hydrogen to these carbonaceous compounds.

Keywords: WC stars, Infrared spectroscopy, Astrochemistry, James Webb Space Telescope, Wolf-Rayet stars