Sazuna/UAT_keywords huggingface dataset:
Wave Period Variability in a Quiescent Solar Prominence. On 2022 September 26, we observed a quiescent solar prominence with Hα imaging spectroscopy using the Solar Dynamics Doppler Imager (SDDI) on board the Solar Magnetic Activity Research Telescope (SMART). Unlike earlier works that detected 4 and 15 minute oscillations through long-slit, 1D wavelet methods, we adapt the wavelet analysis to 3D data to explore the full prominence structure. Complementary data from Solar Dynamics Observatory/Atmospheric Imaging Assembly (304, 171 Å) STEREO-A Extreme Ultraviolet Imager (EUVI; 304 Å), and Solar Orbiter Extreme Ultraviolet Imager/Full Sun Imager (304, 174 Å) enable a multiview, multithermal investigation of wave periodicity across the prominence. Our aim is to characterize how oscillatory periods are distributed in plasma at different temperatures and viewing angles, thereby assessing wave propagation and variability throughout the prominence body. We analyze time series of Doppler signal from SMART/SDDI Hα observations alongside extreme-ultraviolet intensity variations from space-based instruments. We detect oscillatory plasma motions with periods spanning 3─74 minutes. Strong periodicity at 20, 31, and 53 minutes dominates in neutral plasma (Hα), while 13 and 74 minute oscillations are pronounced in the 304 Å passband, concentrated mainly in the central prominence. Additional short-period fluctuations include weaker 3─6 minute oscillations and rapid 30 s transverse waves in Doppler signals near the solar surface. These findings highlight the richness of wave periodicity in quiescent prominences, revealing a dynamic superposition of long- and short-period oscillations and kink-like disturbances. This multi-instrument, 3D perspective advances our understanding of how prominence plasma supports and modulates diverse wave modes.

Keywords: Solar atmosphere, Solar prominences, Helioseismology, Active sun, Solar filaments, Wavelet analysis, Solar oscillations
The Velocity Map Asymmetry of Ionized Gas in MaNGA. II. Correlation between Velocity Map Morphology, Star Formation, and Metallicity in Regular Disk Galaxies. The morphology of ionized gas velocity maps provides a direct probe of the internal gas kinematics of galaxies. Using integral field spectroscopy from SDSS-IV MaNGA, we analyze a sample of 528 low-inclination, regular disk galaxies to investigate the correlations between velocity map morphology, star formation rate, and gas-phase metallicity. We quantify velocity map morphology using harmonic expansion and adopt two complementary diagnostics: the global kinematic asymmetry, which traces nonaxisymmetric perturbations, and the first-order term ratio, which captures axisymmetric radial motions. We find that galaxies with higher kinematic asymmetry are more likely to deviate from the scaling relations, typically lying either above or below the star formation main sequence and systematically below the mass─metallicity relation. In contrast, the first-order term ratio shows only a correlation with gas-phase metallicity in the low-mass range and no significant dependence on star formation rate. Moreover, galaxies below the mass─metallicity relation generally exhibit higher H I gas fractions. These results suggest that external gas accretion is the primary driver of the observed phenomena: inflowing metal-poor gas increases velocity map asymmetry in disk galaxies, dilutes the metallicity, and triggers enhanced star formation. Feedback-driven outflows, bar- and spiral-driven inflows, and galaxy mergers may also contribute but likely play a secondary role.

Keywords: Galaxy kinematics, Galaxy evolution
Contact-binary Evolution with Energy Transfer and Saturated Magnetic Braking. The evolution of low-mass contact binaries is influenced by angular momentum loss, mass and energy transfer (ET), and the nuclear evolution of the components. They have periods shorter than 1 day, and we expect their period evolution to be dominated by magnetic braking (MB). Evidence for saturated MB was presented by studying the period distribution of detached eclipsing binaries. This means the strength of MB likely does not cause a steep period-shrinking relation derived from the widely used Skumanich law. We find further evidence for saturated MB by considering evolutionary models of low-mass contact binaries. We also show that ET must play an important role over a wide parameter range in producing the observed low mass ratios of contact binaries.

Keywords: Binary stars, Contact binary stars
Understanding the Origins of Super-puff Planets: A New Mass-loss Regime Coupled to Planetary Evolution. Super-puffs are a class of low-mass, large-radius planets that have challenged planet formation and evolution models. Their high inferred H/He mass fractions, required to explain their physical sizes, would lead to rapid atmospheric escape, raising questions about their long-term retention. Recent modeling work indicates that low-mass planets typically require 50% less H/He mass to match their observed radius, due to the significant roles of the radiative atmosphere and interior heating from the rock/iron core. Here, through a new quantitative analysis of X-ray and EUV (XUV)─driven escape in sub-Neptunes, we find that previous studies overestimated mass loss, as scaling laws in low-gravity regimes deviate greatly from the widely used energy-limited regime. We define a new regime, thermal-energy-mediated photoevaporation, in which thermal-energy conversion critically sets the mass-loss rate. These effects make super-puffs more resilient to mass loss than previously thought. We develop a coupled evolution model integrating this updated thermal evolution framework with a 1D hydrodynamic photoevaporation model. Applying this novel, joint model to observed super-puffs and young low-density planets, we find that their masses, radii, and transit pressures align with predictions assuming either a clear or hazy atmosphere. This indicates that super-puffs have undergone a combination of boil-off and photoevaporative mass loss, with boil-off dominating the process. Our results indicate that low-density planets typically possess both a thick convective envelope and substantial radiative atmosphere, which contribute to their large radii. For this to occur, these planets must have intermediate masses of 5─10 M⊕ and receive stellar insolation ≲30 F⊕, favoring FG-type stars over M dwarfs.

Keywords: Exoplanet evolution, Atmospheric dynamics, Planetary atmospheres, Planetary structure
Discovery of a Little Red Dot Candidate at z ≳ 10 in COSMOS-web Based on MIRI-NIRCam Selection. JWST has revealed a new high-redshift population called little red dots (LRDs). Since LRDs may be in the early phase of black hole growth, identifying them in the early Universe is crucial for understanding the formation of the first supermassive black holes. However, no robust LRD candidates have been identified at z &gt; 10, because commonly used NIRCam photometry covers wavelengths up to ∼5 μm and is insufficient to capture the characteristic V-shaped spectral energy distributions (SEDs) of LRDs. In this study, we present the first search for z ≳ 10 LRD candidates using both NIRCam and MIRI imaging from COSMOS-Web, which provides the largest joint NIRCam-MIRI coverage to date (0.20 deg2). Taking advantage of MIRI/F770W to remove contaminants, we identify one robust candidate, CW-LRD-z10 at  zphot=10.5−0.6+0.7  with  MUV=−19.9−0.2+0.1mag . CW-LRD-z10 exhibits a compact morphology, a distinct V-shaped SED, and a nondetection in F115W, all consistent with being an LRD at z ∼ 10. Based on this discovery, we place the first constraint on the number density of LRDs at z ∼ 10 with MUV ∼ −20 of  1.2−1.0+2.7×10−6Mpc−3mag−1 , suggesting that the fraction of LRDs among the overall galaxy population increases with redshift, reaching ∼3% at z ∼ 10. Although deep spectroscopy is necessary to confirm the redshift and the nature of CW-LRD-z10, our results imply that LRDs may be a common population at z &gt; 10, playing a key role in the first supermassive black hole formation.

Keywords: Galaxy formation, High-redshift galaxies, Active galactic nuclei, Galaxy evolution
A Mid-infrared Spectroscopic Study of Young Stellar Objects in the SMC Region NGC 346: JWST Detects Dust, Accretion, Ices, and Outflows. We present mid-infrared spectroscopic observations of intermediate-to-high-mass young stellar objects (YSOs) in the low-metallicity star-forming region NGC 346 located within the Small Magellanic Cloud (SMC). We conduct these integral field unit observations with the Medium Resolution Spectroscopy mode of the Mid-Infrared Instrument on board JWST. The brightest and most active star-forming region in the SMC, NGC 346, has a metallicity of ∼1/5 Z⊙, analogous to the era when star formation in the early Universe (z ≃ 2) peaked. We discuss the emission and absorption features present in the spectral energy distributions (SEDs) of five YSOs with coverage from 4.9 to 27.9 μm and three other sources with partial spectral coverage. Via SED model fitting, we estimate their parameters, finding masses ranging from 2.9 to 18.0 M⊙. These targets show dusty silicates, polycyclic aromatic hydrocarbons, and ices of CO2, CO, H2O, and CH3OH in their protostellar envelopes. We measure emission from H2 and atomic fine-structure lines, suggesting the presence of protostellar jets and outflows. We detect H I lines, indicating ongoing accretion, and estimate accretion rates for each source that range from 2.50 × 10−6 to 2.23 × 10−4 M⊙ yr−1, based on the H I (7─6) line emission. We present evidence for a ∼30,000 au protostellar jet traced by fine-structure, H I, and H2 emission about YSO Y535—the first mid-infrared detection of a resolved protostellar outflow in the SMC and the most distant yet detected by JWST.

Keywords: Dust composition, Polycyclic aromatic hydrocarbons, Stellar jets, Star forming regions, Small Magellanic Cloud, Young stellar objects, Star formation, Protostars, Magellanic Clouds
Measurement and Modeling of Electron Temperature in Laboratory Photoionized Plasmas Relevant to Astrophysics. The electron temperature of photoionized plasmas characterizes the thermalization of photoelectrons, impacts the charge-state distribution, emissivity, and opacity through atomic recombination processes, and is needed to perform detailed comparisons with theory predictions. We discuss temperature measurements in laboratory photoionized plasmas and a comparison with model calculations done with several theory approximations and codes. These include a radiation-hydrodynamics simulation and two nonequilibrium heating and ionization models that tracked the evolution of the internal energy of the electrons. Furthermore, for the same physics model and X-ray flux time history, calculations were performed assuming steady-state or time-dependent conditions. The time history of steady-state results correlates with that of the X-ray flux, while that of the time-dependent cases does not, and it is qualitatively and quantitatively different from the steady-state case. Steady-state results significantly overestimated temperature measurements, while time-dependent results produced better approximations, which suggests the importance of transient effects in the experiment and also the need for time-resolved measurements.

Keywords: Photoionization, Laboratory astrophysics, Plasma physics
Challenging the Active Galactic Nucleus Scenario for JWST/NIRSpec Little Red Dot and Non─Little Red Dot Broad Hα Emitters in Light of Nondetection of NIRCam Photometric Variability and X-Ray. JWST has uncovered a substantial population of high-z (z ≳ 4) galaxies exhibiting broad Hα emission lines with a full width at half-maximum exceeding 1000 km s−1. This population consists of a well-known subset called little red dots (LRDs) and the remaining non-LRDs. If all of these broad Hα emitters were attributed to type 1─1.9 active galactic nuclei (AGNs), it would imply a significantly higher number density of low-luminosity AGNs than extrapolated from that of more luminous AGNs. Here, we have examined the rest-frame ultraviolet (UV)-optical flux variability of three LRD and two non-LRD broad Hα emitters using multiepoch, multiband JWST/NIRCam imaging data. The rest-frame temporal sampling interval of the NIRCam data (∼400─500 days/(1 + z)) is comparable to typical variability timescales of AGNs with black hole masses of MBH ∼ 107 M⊙; thus, the flux variations should be detectable if AGNs were present. However, no measurable flux variation over the rest-frame wavelength range of λrest ∼ 1500─9000 Å has been detected, placing stringent upper limits on the variability amplitudes. This result, combined with the X-ray faintness confirmed by the ultradeep Chandra data, indicates that, under the AGN scenario, we need to postulate peculiar Compton-thick broad-line AGNs with either (a) an intrinsically nonvariable AGN disk continuum, (b) a host galaxy-dominated continuum, or (c) scattering-dominated AGN emission. Alternatively, (d) they could be non-AGNs where the broad-line emission originates from unusually fast and dense/low-metallicity star formation-driven outflows or inelastic Raman scattering of stellar UV continua by neutral hydrogen atoms.

Keywords: Active galactic nuclei, High-redshift galaxies
How Many Bursts Does It Take to Form a Core at the Center of a Galaxy?. We present a novel method for systematically assessing the impact of the central potential fluctuations associated with bursty outflows on the structures of dark matter halos for classical and ultrafaint dwarf (UFD) galaxies. Specifically, we use dark-matter-only simulations augmented with a manually added massive particle that modifies the central potential and approximately accounts for a centrally concentrated baryonic component. This approach enables precise control over the magnitude, frequency, and timing of rapid outflow events. We demonstrate that this method can reproduce the established result of core formation for systems that undergo multiple episodes of bursty outflows. In contrast, we also find that equivalent models involving only single (or a small number of) burst episodes do not form cores with the same efficacy. This is important because many UFDs in the local Universe are observed to have tightly constrained star formation histories that are best described by a single early burst of star formation. Using a suite of cosmological zoom-in simulations, we identify the regimes in which single bursts can and cannot form a cored density profile. Our results suggest that it may be difficult to form cores in UFD-mass systems with a single early burst, regardless of its magnitude.

Keywords: Galaxy dark matter halos, Cold dark matter, Galaxy structure
Radiation GRMHD Models of Accretion onto Stellar-mass Black Holes. I. Survey of Eddington Ratios. We summarize results from a survey of radiation-dominated black hole accretion flows across a wide range of mass accretion rates, as well as two values of black hole spin and initial magnetic field geometry. These models apply an algorithm targeting direct solutions to the radiation transport equation in full general relativity and have been enabled by access to modern exascale computing systems. Super-Eddington accretion flows form geometrically thick radiation-pressure-supported disks that drive powerful equatorial outflows. A narrow funnel-shaped photosphere in the inner region results in very low radiative efficiencies in this regime. The structure of near- and sub-Eddington accretion depends on whether there is net vertical magnetic flux at the midplane of the disk. With net flux, the disk forms a thin, dense layer at the midplane surrounded by a magnetically dominated corona, whereas without net flux, the disk remains magnetically dominated everywhere. Although none of our models achieve the magnetically arrested disk regime, those with net vertical flux and a rapidly spinning black hole still produce powerful relativistic jets. Our calculations adopt simple opacity models (with scalings appropriate to stellar-mass black hole accretion). We discuss the application of our results to observations of X-ray binaries and ultraluminous X-ray sources such as Cyg X-3 and SS433. We also speculate on the application of our super-Eddington models to the interpretation of little red dots recently discovered by JWST.

Keywords: Accretion, Black hole physics, X-ray binary stars, Radiative magnetohydrodynamics, Ultraluminous x-ray sources, General relativity
From Wide Triples to Ultracompact X-ray Binaries: Multimessenger Signatures of Dynamically Formed Black Hole─White Dwarf Systems in the LISA Band. Ultracompact X-ray binaries (UCXBs) are a subclass of low-mass X-ray binaries characterized by tight orbits and degenerate donors, which pose significant challenges to our understanding of their formation. Recent discoveries of black hole (BH) candidates with main-sequence or red giant companions suggest that BH─white dwarf (BH─WD) binaries are common in the Galactic field. Motivated by these observations and the fact that most massive stars are born in triples, we show that wide BH─WD systems can naturally form UCXBs through the eccentric Kozai─Lidov (EKL) mechanism. Notably, EKL-driven eccentricity excitations combined with gravitational wave (GW) emission and WD dynamical tides can effectively shrink and circularize the orbit, leading to mass-transferring BH─WD binaries. These systems represent promising multimessenger sources in both X-ray and GW observations. Specifically, we predict that the wide triple channel can produce ∼3─27 (∼1─5) detectable UCXBs in the Milky Way (Andromeda galaxy), including ∼1 system observable by the mHz GW detection of LISA. If the final WD mass can reach sufficiently small values, this channel could contribute up to ∼103 UCXBs in the Galaxy. Furthermore, the identification of tertiary companions in observed UCXBs would provide direct evidence for this formation pathway and yield unique insights into their dynamical origins.

Keywords: Low-mass x-ray binary stars, Gravitational waves
The Photometric Analysis of the Environment Around Two Dusty Star-forming Galaxies at z ∼ 2. Studying the environments of dusty star-forming galaxies (DSFGs) provides insight into whether these luminous systems are reliable signposts of large-scale overdensities. Evidence suggests that individual DSFGs can trace overdense environments, although this association may not be universal. To test this, we investigate the environments surrounding two luminous, gravitationally lensed DSFGs (SDP.17b at zspec = 2.3049 and HELMS-55 at zspec = 2.2834). Using Gemini South Flamingos-2 (F2) Ks-band imaging together with ancillary Subaru Hyper Suprime-Cam and Hubble Space Telescope multiband photometry, we obtain photometric redshifts, zphot, as well as star formation rates and stellar mass estimates for companion galaxies of the DSFGs. At least 5 ± 2 and 15 ± 3 companion galaxies exist with consistent zphot (dz ≤ 0.2) within a projected separation of 5.5 cMpc of SDP.17b and HELMS-55, respectively. These correspond to galaxy overdensities of δ = 0.1 ± 0.2 and δ = 1.0 ± 0.3, with significances of (0.2 ± 0.4)σ and (2.2 ± 0.6)σ, respectively. On the  MH2 -overdensity-significance plane, HELMS-55 may follow the positive correlation between the gas mass and the overdensity significance, while SDP.17b lies well above the relation despite its large gas reservoir, making it a potential outlier. Based on this study of two DSFGs, our photometric analysis suggests that DSFGs can trace the outskirts of protoclusters or associated large-scale structures. However, our small sample prevents firm conclusions about their ability to pinpoint dense cluster cores. Future multi-object spectroscopic observations are required to confirm the membership and star formation properties of the companion galaxies.

Keywords: Galaxy clusters, Galaxy environments, High-redshift galaxy clusters, Protoclusters, Galaxy photometry, Galaxy evolution, Galaxies
Unbound Tails and Compressed Heads: A JCMT Study of the SFO 38 Cloud. SFO 38, located in the Cepheus molecular cloud within the northern part of the H II region IC 1396, is shaped by intense ultraviolet (UV) radiation from the nearby O6.5V-type star HD 206267 and represents a classic example of a bright-rimmed cloud undergoing radiatively driven implosion (RDI). While previous studies have examined the southern globule using CS and 13CO (1─0), we present a refined analysis using high-resolution JCMT-HARP observations in the 12CO, 13CO, and C18O (J = 3 → 2) lines, deriving key physical parameters along with virial mass and turbulence properties of the southern head. We also perform the first detailed investigation of the northeastern and northwestern tails, determining their morphological dimensions and internal conditions, including excitation temperature, column density, mass, and volume density. Spectral and stability analyses reveal that the tail regions are gravitationally unbound and dynamically expanding, explaining the lack of active star formation. Our results further shed light on the evolutionary fate of these structures, assessing whether they may accumulate sufficient material to become future sites of star formation or remain quiescent. Overall, this work highlights the dual role of RDI in this bright-rimmed cloud: while it triggers star formation in the dense head, it simultaneously disperses and dynamically reshapes the extended tails.

Keywords: A subgiant stars
X-Ray Observations of Nova Scorpii 2023 (V1716 Sco) in Outburst. Nova Scorpii 2023 (V1716 Sco) was first detected as a luminous supersoft X-ray source (SSS) 93 days after outburst and continued emitting soft X-rays for over 2 months, until it was too close to the Sun to observe. The nova was monitored with the Swift X-ray Telescope and the Neutron Star Interior Composition Explorer (NICER) on the International Space Station, and in long exposures with the Chandra High Resolution Camera and Low Energy Transmission Grating (LETG) on days 128, 129, and 183─185 after optical maximum. Swift detected a rapidly decaying SSS when observations resumed, constraining the phase of constant bolometric luminosity to ∼9 months. The SSS flux was irregularly variable. A nearly threefold increase in flux was observed between 2023 August and October in the 15─35 Å range, from 3.5 × 10−11 to 9.4 × 10−11 erg cm−2 s−1. The SSS duration and effective temperature derived from the October LETG spectra indicate a massive white dwarf (WD) with temperature fitting nova evolutionary tracks for a ≍1.2 M⊙ WD; emission lines superimposed on the WD continuum are attributed to surrounding shocked ejecta. We present a timing study based on Chandra and archival NICER data. The irregular variability timescale was days, but a ∼77.9 s periodic modulation in the SSS flux with varying amplitude was measured in many observations. Our analysis shows that this period was stable; short drifts derived with NICER, but not in long, uninterrupted Chandra exposures, are artifacts of measuring variable amplitude modulation. We suggest the modulations are associated with the WD rotation.

Keywords: X-ray astronomy, High energy astrophysics, White dwarf stars, Novae, Time domain astronomy, Cataclysmic variable stars