Sazuna/UAT_keywords huggingface dataset:
Unveiling the Dual Nature of V1180 Cas: UXor-like Dips and EXor-like Bursts across a Decade. We present a detailed analysis of the long-term photometric and spectroscopic evolution of V1180 Cas over a decade, aiming to identify the dominant mechanisms behind its variability. We combine multiband light curves from 1999 to 2025 with over 30 epochs of optical to near-infrared (NIR) spectroscopy (0.5─2.5 μm), analyzing variability patterns, color behavior, and emission line diagnostics. We investigate the temporal evolution of accretion and outflow indicators and their correlation with photometric states. The light curve reveals a transition from sporadic early dimming events to a quasi-periodic pattern since 2018, with 11 major dips showing asymmetry and stochastic substructure. Color─magnitude diagrams show classic UXor-like blueing during deep minima, while NIR and mid-infrared color changes indicate thermal evolution of the disk. Spectroscopic analysis reveals persistent hydrogen, Ca II, He I, and forbidden line emission. Accretion diagnostics track photometric variability, and forbidden lines often intensify during dips, implying a physical link between extinction and outflows. Estimated accretion rates range from ∼10−8 to 10−7 M⊙ yr−1; the outflow rate and density diagnostics are consistent with disk winds and shock-excited jets. V1180 Cas demonstrates dual-mode variability driven by both variable circumstellar extinction and episodic accretion events. The hybrid UXor/EXor behavior, combined with evolving disk signatures and persistent outflows, suggests a young stellar object undergoing coupled accretion─extinction─outflow evolution. Continued monitoring will be essential to fully resolve the physical processes shaping its variability.

Keywords: Classical T Tauri stars, Stellar winds, Pre-main sequence stars, Star formation, Spectroscopy, Photometry
High-frequency Continuous Gravitational Wave Search in LIGO O3 Public Data with Einstein@Home. We search for nearly monochromatic gravitational-wave signals with frequencies 800.0 Hz ≤ f ≤ 1686.0 Hz and spin-down  −2.7×10−9Hzs−1≤ḟ≤0.2×10−9Hzs−1 . We use LIGO O3 public data from the Hanford and Livingston detectors, and deploy this search on the Einstein@Home volunteer-computing project. This is the most sensitive search carried out to date in this parameter space. Our results are consistent with a nondetection. We set upper limits on the gravitational-wave amplitude h0 and translate these to upper limits on neutron star ellipticity and on r-mode amplitude. The most stringent upper limits are at 800 Hz, with h0 = 1.32 × 10−25 at the 90% confidence level. Searching in the high-frequency bands allows us to probe astrophysically interesting ellipticities with our results, excluding isolated neutron stars rotating faster than 2.5 ms with ellipticities  ϵ≥1.96×10−8d100pc  within a distance d from Earth. Our results also exclude r-mode amplitudes  α≥7×10−7d100pc  for neutron stars spinning faster than 400 Hz.

Keywords: Gravitational wave astronomy, Neutron stars, Gravitational waves
HSTPROMO Internal Proper-motion Kinematics of Dwarf Spheroidal Galaxies. II. Velocity Anisotropy and Dark Matter Cusp Slope of Sculptor. We analyze three epochs of Hubble Space Telescope imaging over 20 yr for the Sculptor dwarf spheroidal galaxy, measuring precise proper motions for 119 stars and combining them with 1760 existing line-of-sight (LOS) velocities. This catalog yields the first radially resolved 3D velocity dispersion profiles for Sculptor. We confirm mild oblate rotation, with major-axis velocities reaching ∼2 km s−1 beyond  20.'0 . Using a methodology similar to that in the first paper in this series, we solve the Jeans equations in oblate axisymmetric geometry to infer the galaxy's mass profile. Our modeling reveals a significant degeneracy due to the unknown galaxy inclination, which is overlooked under spherical symmetry assumptions. This degeneracy allows acceptable fits across a range of dark matter profiles, from cuspy to cored. While we do not directly constrain the inclination with our Jeans models, higher-order LOS velocity moments provide useful additional constraints: comparisons with SCALEFREE models from J. H. J. de Bruijne et al. favor highly flattened (more face-on) configurations. Adopting an inclination well consistent with these comparisons ( i=57.°1 ), we find, alongside radial velocity anisotropy, a dark matter density slope of  Γdark=0.29−0.41+0.31  within the radial extent of the 3D velocity data (i.e., within ∼120─240 pc), ruling out a cusp with Γdark ≤ −1 at 99.8% confidence. This confidence increases for lower inclinations and decreases drastically for nearly edge-on configurations. The results qualitatively agree with Λ cold dark matter, self-interacting dark matter, and fuzzy dark matter scenarios that predict core formation, while our specific measurements provide quantitative constraints on the prescriptions of feedback, cross sections, or particle masses required by these models, respectively.

Keywords: Galaxy dynamics, Dwarf galaxies, Astronomy data analysis, Galaxy structure, Galaxy kinematics, Proper motions, Dark matter
Fundamental Understanding of Magnetic Reconnection via Spiral CT Scan. IV. Whistler Waves. For the first time, we reveal the distribution of whistler waves around a reconnection X-line by using the spiral CT scan technique, which is a novel technique analogous to that used in hospitals. This X-line was detected by the Magnetospheric Multiscale mission at the terrestrial magnetopause and has been widely believed to host a non-guide-field reconnection. With the help of this advanced technique, we find that (1) Whistler waves exist near the X-point and in the inflow region, but do not exist around the magnetosheath-side separatrix line; (2) generally, the whistler-wave power is strong near the X-point, medium in the magnetosheath inflow region, and weak in the magnetosphere inflow region; (3) the wave normal angle is quasi-perpendicular near the X-point, oblique in the magnetosphere inflow region, and quasi-parallel in the magnetosheath inflow region; and (4) the Poynting flux has random directions, meaning that these whistlers are generated locally. These whistler waves contribute significantly to the electron demagnetization, and therefore they may trigger the occurrence of magnetic reconnection.

Keywords: Space plasmas, Solar magnetic reconnection, Plasma physics
Young Planets around Young Accreting Stars. I. Migration and Inner Stalling Orbits. Planet migration in protoplanetary disks significantly influences exoplanet architectures. We investigate various migration mechanisms for young planets close to young stars. To quantify the stochastic migration driven by turbulent disks, we incorporate planets into existing 3D MHD-disk simulations of magnetospheric accretion. We further model these turbulent torques analytically using a modified Gaussian process. Migration timescales for other processes, including the smooth Type I/II migration, planet─star tidal and magnetic interactions, and aerodynamical drag with the magnetosphere are also estimated analytically. Given that our simulation reveals a very low surface density for this very inner MHD-turbulent region, the resulting disk migration here is significantly slower than previously estimated. Earth-mass planets have migration timescales tmig ≳ 108 yr in this region. Thus, they are unlikely to migrate past the dead zone inner boundary (RDZIB) into the MHD-region before the disk dissipates. Only giant planets could migrate inward within the turbulent disk, and may stall at the magnetospheric truncation radius (RT). A simplified planet population synthesis demonstrates that, at the end of the disk phase, all planets around solar-mass stars typically stall at ≲0.1 au, since RT ∼ RDZIB. However, around 2 M⊙ stars, higher-mass planets stall significantly closer to the star compared to low-mass planets, due to RT ≪ RDZIB. These results are consistent with recent exoplanet demographics around different types of stars. Finally, the turbulence in our simulations may not be sufficient to break resonant planet pairs according to previous analytical criteria, which, on the other hand, needs to be confirmed by future 3D simulations.

Keywords: Accretion, Planetary-disk interactions, Protoplanetary disks, Planetary migration, Magnetohydrodynamical simulations
A XRISM/Resolve View of the Dynamics in the Hot Gaseous Atmosphere of M87. The XRISM/Resolve microcalorimeter directly measured the gas velocities in the core of the Virgo Cluster, the closest example of active galactic nucleus (AGN) feedback in a cluster. This proximity allows us to resolve the kinematic impact of feedback on scales down to 5 kpc. Our spectral analysis reveals a high velocity dispersion of  σv=262−38+45  km s−1 near the AGN, which steeply declines to ∼60 km s−1 between 5 and 25 kpc in the northwest direction. The observed line-of-sight bulk velocity in all regions is broadly consistent with the central galaxy, M87, with a mild trend toward blueshifted motions at larger radii. Systematic uncertainties have been carefully assessed and do not affect the measurements. The central velocities, if attributed entirely to isotropic turbulence, correspond to a transonic intracluster medium at sub-6 kpc scales with 3D Mach number  0.69-0.11+0.14  and a nonthermal pressure fraction of  21-5+7% . Simple models of weak shocks and sound waves and calculations assuming isotropic turbulence both support the hypothesis that the velocity field reflects a mix of shock-driven expansion and turbulence. Compared to other clusters observed by XRISM to date, M87's central region stands out as the most kinematically disturbed, exhibiting both the highest velocity dispersion and the largest 3D Mach number, concentrated at the smallest physical scales.

Keywords: Galaxy clusters, X-ray astronomy, High resolution spectroscopy, Virgo Cluster, Intracluster medium
Thermal Baroclinic Instabilities in Accretion Disks. II. Numerical Experiments for the Goldreich─Schubert─Fricke Instability and the Convective Overstability in Disks around Young Stars. The linear stability analysis of a stratified rotating fluid (see Paper I) showed that disks with a baroclinic stratification under the influence of thermal relaxation will become unstable to thermal instabilities. One instability is the Goldreich─Schubert─Fricke (GSF) instability, which is the local version of the vertical shear instability (VSI), and the other is a thermal overstability, the convective overstability (COS). In this paper we reproduce the analytic predicted growth rates for both instabilities in numerical experiments of small axisymmetric sections of vertically isothermal disks with a radial temperature gradient, especially for cooling times longer than the critical cooling time for VSI. In this cooling time regime our simulations reveal the simultaneous and independent growth of both modes: COS and GSF instability. We consistently observe that GSF modes exhibit a faster growth rate compared to COS modes. Near the midplane, GSF modes eventually stop growing, while COS modes continue to grow and ultimately dominate the flow pattern. Away from the midplane, we find GSF modes to saturate, when bands of constant angular momentum have formed. In these bands we observe the formation and growth of eddies driven by the baroclinic term, further enhancing the velocity perturbations. In geophysics this effect is known as horizontal convection or sea-breeze instability. Three-dimensional simulations will have to show whether similar effects will occur when axisymmetry is not enforced. Our local simulations help to reveal the numerical resolution requirements to observe thermal instabilities in global simulations of disks around young stars.

Keywords: Hydrodynamical simulations, Solar nebulae, Solar system formation, Hydrodynamics, Protoplanetary disks, Circumstellar disks, Astrophysical fluid dynamics
Millimeter-wave Rotational Spectroscopy and Interstellar Search for 2-Mercaptoethanol (HSCH<SUB>2</SUB>CH<SUB>2</SUB>OH). Sulfur is one of the most abundant elements in the interstellar medium (ISM) and a key component for life, yet little is understood about its chemistry in the ISM. While increasingly larger molecules containing sulfur and oxygen are being observed in the ISM, the largest organic molecule containing oxygen and sulfur, monothioformic acid (HC(O)SH), was only recently detected. There is still no identification of a complex organic molecule (COM, carbon-bearing molecule with six or more atoms) containing both oxygen- and sulfur-bearing functional groups. We extended the laboratory rotational spectrum of 2-mercaptoethanol (HSCH2CH2OH), one of the simplest saturated COMs containing both oxygen and sulfur, into millimeter/submillimeter wavelengths, providing an improved spectral catalog at frequencies required for its interstellar identification. Millimeter/submillimeter transitions were measured for 2-mercaptoethanol from ∼82 to 450 GHz. Using the resulting spectral catalog, we searched for its rotational emission toward the Galactic Center molecular cloud G+0.693-0.027, the high-mass star-forming region Sgr B2(N), the cold dark core TMC-1, the hot core in Orion, and toward the hot corino surrounding the low-mass protostar IRAS 16293-2422B. An extensive analysis of 8584 transitions of 2-mercaptoethanol with  Jmax″  = 104, and  Kamax″  = 64 is provided. The resulting fit includes a full set of quartic, sextic, and octic distortion constants. We report the nondetection of 2-mercaptoethanol and provide column density upper limits toward each source. While our interstellar search for 2-mercaptoethanol did not result in a detection, the upper limits on its column density provide important constraints for chemical models on the formation of oxygen- and sulfur-bearing COMs.

Keywords: Millimeter-wave spectroscopy, Molecular spectroscopy, Interstellar medium
Wind-fed Supermassive Black Hole Accretion in the Ultracompact Dwarf Galaxy M60-UCD1. Ultracompact dwarf galaxies (UCDs) are thought to be remnants of stripped galactic nuclei, among which a handful are known to host a central supermassive black hole (SMBH). As in stripped nuclear star clusters, the SMBHs in UCDs may be fed by stellar winds from old stellar populations, in the absence of substantial gas reservoirs and galactic inflows. In this work, we investigate such a wind-fed accretion scenario for M60-UCD1, which harbors a confirmed 2 × 107 M⊙ SMBH and exhibits X-ray emission suggestive of SMBH accretion signature. Using three-dimensional hydrodynamical simulations, we simulate the SMBH accreting stellar winds from approximately 1500 asymptotic giant branch stars, and explore the role of ram pressure from the ambient interstellar or intracluster medium. After 5 Myr, the majority of the stellar winds form a cold gas disk (∼1000 M⊙) within ∼10 pc as well as the SMBH's gravitational sphere of influence. Within the inner 104 rg, this disk transitions into a hot (∼107─109 K), geometrically thick corona that dominates the X-ray emission. The SMBH achieves an accretion rate of ∼10−5 M⊙ yr−1, yielding an X-ray luminosity of ∼7 × 1037 erg s−1, consistent with observations. Including ram pressure stripping reduces both the accretion rate and luminosity by about a factor of 2. Our results suggest that the X-ray counterpart of M60-UCD1 originates from a weakly accreting SMBH fed by stellar winds, with broader insights into the feeding mechanisms of central massive black holes and the origins of X-ray sources in other UCDs.

Keywords: Accretion, Supermassive black holes, Hydrodynamical simulations, Stellar winds, Ultracompact dwarf galaxies, Star clusters
Ring-gap Structures in the Class I Circumstellar Disk of CrA IRS 2 Associated with the Magnetic Flux-driven Bubble. Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations with 0 .″ 1 resolution have revealed characteristic substructures in circumstellar disks around young Class I sources, providing clues to the early stages of morphological disk evolution. In this paper, we applied PRIISM imaging to ALMA archival Band 6 continuum data of the circumstellar disk around the Class I protostar CrA IRS 2, located in the Corona Australis molecular cloud, which is associated with an extended gas ring attributed to magnetic flux advection driven by interchange instability. The dust continuum image, with 1.5 times higher spatial resolution than conventional imaging, revealed for the first time an early-phase circumstellar disk with both inner central hole and outer ring-gap structures, making CrA IRS 2 the youngest system known to exhibit such features based on its bolometric temperature of Tbol = 235 K. To examine planet─disk interaction as one possible origin of the outer ring-gap structure, we found the measured depth and width to be consistent with planet─disk interaction models, suggesting the existence of a giant planet with a mass of 0.1─1.8 MJup. The additional mechanism required for rapid planet formation could be the magnetic flux dissipation driven by the interchange instability, which suppresses magnetorotational-instability-driven turbulence and extends the dead zone, allowing efficient dust growth and the early formation of planets. This system thus provides new insight into how substructures and planet formation can emerge during the early, accreting phase of disk evolution.

Keywords: Radio interferometry, Magnetic fields, Protoplanetary disks, Circumstellar disks
The Timescales of Embedded Star Formation as Observed in STARFORGE. Star formation occurs within dusty molecular clouds that are then disrupted by stellar feedback. However, the timing and physical mechanisms that govern the transition from deeply embedded to exposed stars remain uncertain. Using the STARFORGE simulations, we analyze the evolution of "embeddedness," identifying what drives emergence. We find the transition from embedded to exposed is fast for individual stars, within 1.3 Myr after the star reaches its maximum mass. This rapid transition is dominated by massive stars, which accrete while remaining highly obscured until their feedback eventually balances, then overcomes, the local accretion. For these massive stars, their maximum mass is reached simultaneously with their emergence. Once these stars are revealed, their localized, pre-supernova feedback then impacts the cloud, driving gas clearance. Because massive stars dominate the luminosity, their fast, local evolution dominates the light emergence from the dust. We calculate the dependence of these processes on the mass of the cloud and find that emergence always depends on when massive stars form, which scales with the cloud's free-fall time. We also measure the evolution of dust and Hα luminosities, where for ∼2 Myr, these tracers outshine the emerging stellar continuum, reaching their peak when gas and dust remain tightly coupled to the massive stars. These results closely resemble observationally observed lifetimes, tying the observable dust and line emission directly to the same localized processes that drive stellar emergence, evidence that our simulated de-embedding physics is representative of real star-forming regions. Thus, because the initial embedding of the most luminous stars is highly local, the emergence of stars is a faster, earlier, more local event than the overall disruption of the cloud by gas expulsion.

Keywords: Protoclusters, Star formation, Stellar associations, Star clusters
A Comprehensive Photometric Study of the Eclipsing SU UMa-type Cataclysmic Variable OY Carinae. We present a comprehensive photometric study of the eclipsing dwarf nova OY Car based on ground-based observations and archival data from the Transiting Exoplanet Survey Satellite (TESS) and AAVSO. Eclipse timing analysis reveals a secular increase in the orbital period at a rate of +5.70 × 10−13 s s−1, superimposed with a cyclic variation with an amplitude of 57.11 s and a period of 33.41 yr. This period increase cannot be attributed to either mass transfer or a period bouncer, suggesting the presence of an unrecognized mechanism. The cyclic oscillation is most effectively interpreted as a gravitational perturbation from an undetected circumbinary object. The potential tertiary companion is estimated to be a giant planet with a mass of 11.5(±3.1)MJup in a circular orbit. The TESS light curve captures one superoutburst and one normal outburst. Analysis of the eclipse depth versus the out-of-eclipse flux reveals a linear correlation during quiescence, but with a lower slope before the superoutburst, consistent with disk structure changes predicted by the thermal-tidal instability model. Deviations from linearity during outbursts manifest as hysteresis loops, indicative of significant disk expansion. Eclipse analysis reveals that the normal outburst is of the outside-in type, while the superoutburst exhibits a quasi-periodic O ─ C modulation indicating a precessing eccentric disk. We derive a mean superhump period of 0.06456 day via the beat relation, which yields a mass ratio of q = 0.1049 using an empirical relation. We also study the superhump evolution, identifying the standard three-stage evolution. The positive period derivative in stage B and the discrepancy between dynamical and empirical mass ratio estimates confirm the significant influence of pressure effects on the accretion disk precession.

Keywords: Close binary stars, Compact binary stars, Interacting binary stars, Dwarf novae, SU Ursae Majoris stars, Eclipsing binary stars, Cataclysmic variable stars
Beyond UV: Rest-frame B-band and Apparent Luminosity Functions of z = 5─9 Galaxies. We present new measurements of galaxy luminosity functions (LFs) from JWST/NIRCam imaging over the redshift range z = 4.5─9.7, using photometric catalogs from JADES and public extragalactic fields. Our analysis includes rest-frame UV and B-band LFs, as well as apparent LFs in F090W, F115W, F200W, F356W, and F444W. We present the first constraints on the rest-frame B-band LF at z ∼ 7─8 and extend existing measurements at z ∼ 5 to MB = −18 mag. The B-band LFs evolve more strongly with redshift than UV LFs, though both decline more gradually than predicted by simulations at z &gt; 5. No single existing simulation reproduces all observed trends, with discrepancies likely driven by assumptions about binary evolution and stellar population synthesis models. The apparent LFs in F356W and F444W show hints of a bright-end excess at all redshifts, extending to fainter magnitudes at higher redshift. While extreme emission-line galaxies may partially account for it, the excess may also indicate a population of moderately red, optically bright sources—potentially dusty star-forming galaxies or obscured AGNs. Finally, we find that rest-frame B-band luminosity correlates more tightly with stellar mass than UV, making it a powerful tracer of mass assembly and reinforcing the diagnostic value of rest-frame optical LFs in uncovering the physical processes that drive early galaxy formation.

Keywords: Luminosity function, Galaxy luminosities, Galaxy properties, Scaling relations