Sazuna/UAT_keywords huggingface dataset:
Water-rich Disks around Late M Stars Unveiled: Exploring the Remarkable Case of Sz 114. We present an analysis of the JDISCS JWST/MIRI-MRS spectrum of Sz 114, an accreting M5 star surrounded by a large dust disk with a shallow gap at ~39 au. The spectrum is molecule-rich; we report the detection of water, CO, CO2, HCN, C2H2, and H2. The only identified atomic/ionic transition is from [Ne II] at 12.81 μm. A distinct feature of this spectrum is the forest of water lines with the 17.22 μm emission surpassing that of most mid-to-late M star disks by an order of magnitude in flux and aligning instead with disks of earlier-type stars. Moreover, the flux ratios of C2H2/H2O and HCN/H2O in Sz 114 also resemble those of earlier-type disks, with a slightly elevated CO2/H2O ratio. While accretional heating can boost all infrared lines, the unusual properties of Sz 114 could be explained by the young age of the source, its formation under unusual initial conditions (a large massive disk), and the presence of dust substructures. The latter delays the inward drift of icy pebbles and helps preserve a lower C/O ratio over an extended period. In contrast, mid-to-late M-star disks-which are typically faint, small in size, and likely lack significant substructures-may have more quickly depleted the outer icy reservoir and already evolved out of a water-rich inner disk phase. Our findings underscore the unexpected diversity within mid-infrared spectra of mid-to-late M-star disks, highlighting the need to expand the observational sample for a comprehensive understanding of their variations and thoroughly test pebble drift and planet formation models.

Keywords: Molecular gas, Molecular spectroscopy, Planetary system formation, Infrared astronomy, Pre-main sequence stars, Protoplanetary disks, Circumstellar disks
Early-time Ultraviolet and Optical Hubble Space Telescope Spectroscopy of the Type II Supernova 2022wsp. We report early-time ultraviolet (UV) and optical spectroscopy of the young, nearby Type II supernova (SN) 2022wsp obtained by the Hubble Space Telescope (HST)/STIS at about 10 and 20 days after the explosion. The SN 2022wsp UV spectra are compared to those of other well-observed Type II/IIP SNe, including the recently studied Type IIP SN 2021yja. Both SNe exhibit rapid cooling and similar evolution during early phases, indicating a common behavior among SNe II. Radiative-transfer modeling of the spectra of SN 2022wsp with the TARDIS code indicates a steep radial density profile in the outer layer of the ejecta, a solar metallicity, and a relatively high total extinction of E(B - V) = 0.35 mag. The early-time evolution of the photospheric velocity and temperature derived from the modeling agree with the behavior observed from other previously studied cases. The strong suppression of hydrogen Balmer lines in the spectra suggests interaction with a preexisting circumstellar environment could be occurring at early times. In the SN 2022wsp spectra, the absorption component of the Mg II P Cygni profile displays a double-trough feature on day +10 that disappears by day +20. The shape is well reproduced by the model without fine-tuning the parameters, suggesting that the secondary blueward dip is a metal transition that originates in the SN ejecta.

Keywords: Ultraviolet spectroscopy, Spectroscopy
CI Traces the Disk Atmosphere in the IM Lup Protoplanetary Disk. The central star and its energetic radiation fields play a vital role in setting the vertical and radial chemical structure of planet-forming disks. We present observations that, for the first time, clearly reveal the UV-irradiated surface of a protoplanetary disk. Specifically, we spatially resolve the atomic-to-molecular (C I-to-CO) transition in the IM Lup disk with Atacama Large Millimeter/submillimeter Array archival observations of [C I] 3P1-3P0. We derive a C I emitting height of z/r ≳ 0.5 with emission detected out to a radius of ≈600 au. Compared to other systems with C I heights inferred from unresolved observations or models, the C I layer in the IM Lup disk is at scale heights almost double that of other disks, confirming its highly flared nature. C I arises from a narrow, optically thin layer that is substantially more elevated than that of 12CO (z/r ≈ 0.3-0.4), which allows us to directly constrain the physical gas conditions across the C I-to-CO transition zone. We also compute a radially resolved C I column density profile and find a disk-averaged C I column density of 2 × 1016 cm-2, which is ≈3-20× lower than that of other disks with spatially resolved C I detections. We do not find evidence for vertical substructures or spatially localized deviations in C I due, e.g., to either an embedded giant planet or a photoevaporative wind that have been proposed in the IM Lup disk, but emphasize that deeper observations are required for robust constraints.

Keywords: Planet formation, Photodissociation regions, Astrochemistry, Protoplanetary disks, High angular resolution
A Primordial Origin for the Gas-rich Debris Disks around Intermediate-mass Stars. While most debris disks consist of dust with little or no gas, a fraction have significant amounts of gas detected via emission lines of CO, ionized carbon, and/or atomic oxygen. Almost all such gaseous debris disks known are around A-type stars with ages up to 50 Myr. We show, using semianalytic disk evolution modeling, that this can be understood if the gaseous debris disks are remnant protoplanetary disks that have become depleted of small grains compared to the interstellar medium. Photoelectric heating by the A stars' far-UV (FUV) radiation is then inefficient, while the stars' extreme-UV (EUV) and X-ray emissions are weak owing to a lack of surface convective zones capable of driving magnetic activity. In this picture, it is relatively difficult for stars outside the range of spectral types from A through early B to have such long-lived gas disks. Less-massive stars have stronger magnetic activity in the chromosphere, transition region, and corona with resulting EUV and X-ray emission, while more-massive stars have photospheres hot enough to produce strong EUV radiation. In both cases, primordial disk gas is likely to photoevaporate well before 50 Myr. These results come from 0D disk evolution models where we incorporate internal accretion stresses, MHD winds, and photoevaporation by EUV and X-ray photons with luminosities that are functions of the stellar mass and age. A key issue this work leaves open is how some disks become depleted in small dust so that FUV photoevaporation slows. Candidates include the grains' growth, settling, radial drift, radiation force, and incorporation into planetary systems.

Keywords: A stars, Extreme ultraviolet astronomy, Protoplanetary disks, Interstellar medium, Exoplanet formation, Debris disks, Stellar evolution
Investigations of Flaring Plasma Parameters during an M-class Flare Using the Differential Evolution Method and XSM/Chandrayaan-2 Observations. We employ the differential evolution (DE) method to analyze observations from the Solar X-Ray Monitor on board the Chandrayaan-2 spacecraft. DE belongs to the family of evolutionary algorithms that find solutions using mechanisms inspired by biological processes. This approach enables us to simultaneously calculate the distribution of the differential emission measure and elemental abundances through an iterative process. We establish a model for the emission sources of flaring plasma, incorporating temperature, emission measure, and abundances of eight elements: Mg, Al, Si, S, Ar, Ca, Fe, and Ni, for an M3.9 GOES-class solar flare that occurred on 2021 May 7 (SOL2021-05-07T19:04). Our analysis covers various phases of the flare, determining the evolution of temperature, emission measure, and elemental abundances. Additionally, utilizing data from the Spectrometer Telescope for Imaging X-rays on board the Solar Orbiter, we investigate the evolution of hard X-ray source morphology, source volume, electron density, and thermal behavior of the flaring plasma throughout the event. The results reveal notable variations in elemental abundances between photospheric and coronal values during different flare phases. This emphasizes the significance of elemental abundance information in comprehending X-ray emissions during solar flares.

Keywords: Solar abundances, The Sun, Solar corona, Solar x-ray flares
Day–Night Transport-induced Chemistry and Clouds on WASP-39b: Gas-phase Composition. JWST has recently detected the first robust photochemical product on an exoplanet: sulfur dioxide (SO2) on WASP-39b. The data from the NIRISS instrument also reveal signs of partial coverage of clouds. Most of the previous studies have focused on interpreting spectral data with 1D models. To explore how the chemical species and cloud particles are altered by global circulation, we applied a 2D photochemical model and a 2D microphysical cloud model separately to postprocess the thermal and dynamical structures simulated by a 3D general circulation model of WASP-39b. We found that SO2 produced by photochemistry on the dayside can be transported to the nightside owing to the efficient replenishment of horizontal transport. The morning–evening limb differences in methane (CH4) abundances predicted by the 1D models disappeared after horizontal transport is included. Similarly, the inclusion of horizontal transport also reduced the limb differences in SO2. Our modeling results suggest that the fast zonal wind results in minimal or negligible limb asymmetry in composition. Based on the synthetic spectra generated by our 2D atmosphere simulations, we propose that observing SO2 absorption in the emission spectra of WASP-39b at different phases may offer opportunities to probe the horizontal quenching process of photochemical products. We will focus on the gas-phase chemistry in this paper and leave the results regarding clouds in the subsequent paper as part of the series.

Keywords: Exoplanet atmospheric composition , Extrasolar gaseous planets, Exoplanet atmospheres
Digging into the Interior of Hot Cores with ALMA: Spiral Accretion into the High-mass Protostellar Core G336.01-0.82. We observed the high-mass star-forming core G336.01-0.82 at 1.3 mm and 0.″05 (~150 au) angular resolution with the Atacama Large Millimeter/submillimeter Array (ALMA) as part of the Digging into the Interior of Hot Cores with ALMA survey. These high-resolution observations reveal two spiral streamers feeding a circumstellar disk at opposite sides in great detail. Molecular line emission from CH3OH shows velocity gradients along the streamers consistent with infall. Similarly, a flattened envelope model with rotation and infall implies a mass larger than 10 M ☉ for the central source and a centrifugal barrier of 300 au. The location of the centrifugal barrier is consistent with local peaks in the continuum emission. We argue that gas brought by the spiral streamers is accumulating at the centrifugal barrier, which can result in future accretion burst events. A total high infall rate of ~4 × 10-4 M ☉ yr-1 is derived by matching models to the observed velocity gradient along the streamers. Their contribution accounts for 20%-50% the global infall rate of the core, indicating streamers play an important role in the formation of high-mass stars.

Keywords: Massive stars, Star forming regions, Star formation
Discovery of the Closest Ultra-stripped Supernova: SN 2021agco in UGC 3855. We present the discovery and studies of the helium-rich, fast-evolving supernova (SN) 2021agco at a distance of ~40 Mpc. Its early-time flux is found to rise from half peak to the peak of -16.06 ± 0.42 mag in the r band within ${2.4}_{-1.0}^{+1.5}$ days, and the post-peak light curves also decline at a much faster pace relative to normal stripped-envelope supernovae (SNe) of Type Ib/Ic. The early-time spectrum of SN 2021agco (t ≈ 1.0 days after the peak) is characterized by a featureless blue continuum superimposed with a weak emission line of ionized C III, and the subsequent spectra show prominent He I lines. Both the photometric and spectroscopic evolution show close resemblances to SN 2019dge, which is believed to have an extremely stripped progenitor. We reproduce the multicolor light curves of SN 2021agco with a model combining shock-cooling emission with 56Ni decay. The best-fit results give an ejecta mass of ≈0.3 M ⊙ and a synthesized nickel mass of ≈2.2 × 10-2 M ⊙. The progenitor is estimated to have an envelope radius of R env ≈ 80 R ⊙ and a mass of M env ≈ 0.10 M ⊙. All these suggest that SN 2021agco can be categorized as an ultra-stripped SN Ib, representing the closest object of this rare subtype. This SN is found to explode in the disk of a Sab-type galaxy with an age of ~10.0 Gyr and low star-forming activity. Compared to normal SNe Ib/c, the host galaxies of SN 2021agco and other ultra-stripped SNe tend to have relatively lower metallicity, which complicates the properties of their progenitor populations.

Keywords: Type Ib supernovae, Transient sources, Supernovae
The Effect of the Parametric Decay Instability on the Morphology of Coronal Type III Radio Bursts. The nonlinear evolution of Alfvén waves in the solar corona leads to the generation of Alfvénic turbulence. This description of the Alfvén waves involves parametric instabilities where the parent wave decays into slow mode waves giving rise to density fluctuations. These density fluctuations, in turn, play a crucial role in the modulation of the dynamic spectrum of type III radio bursts, which are observed at the fundamental of local plasma frequency and are sensitive to the local density. During observations of such radio bursts, fine structures are detected across different temporal ranges. In this study, we examine density fluctuations generated through the parametric decay instability (PDI) of Alfvén waves as a mechanism to generate striations in the dynamic spectrum of type III radio bursts using magnetohydrodynamic simulations of the solar corona. An Alfvén wave is injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components, which subsequently undergo the PDI instability. The type III burst is modeled as a fast-moving radiation source that samples the background solar wind as it propagates to emit radio waves. We find the simulated dynamic spectrum to contain striations directly affected by the multiscale density fluctuations in the wind.

Keywords: Magnetohydrodynamics, Solar physics, Solar radio emission, Alfven waves, Radio bursts, Solar corona
Real-time Experimental Demonstrations of a Photonic Lantern Wave-front Sensor. The direct imaging of an Earth-like exoplanet will require sub-nanometric wave-front control across large light-collecting apertures to reject host starlight and detect the faint planetary signal. Current adaptive optics systems, which use wave-front sensors that reimage the telescope pupil, face two challenges that prevent this level of control: non-common-path aberrations, caused by differences between the sensing and science arms of the instrument; and petaling modes: discontinuous phase aberrations caused by pupil fragmentation, especially relevant for the upcoming 30 m class telescopes. Such aberrations drastically impact the capabilities of high-contrast instruments. To address these issues, we can add a second-stage wave-front sensor to the science focal plane. One promising architecture uses the photonic lantern (PL): a waveguide that efficiently couples aberrated light into single-mode fibers (SMFs). In turn, SMF-confined light can be stably injected into high-resolution spectrographs, enabling direct exoplanet characterization and precision radial velocity measurements; simultaneously, the PL can be used for focal-plane wave-front sensing. We present a real-time experimental demonstration of the PL wave-front sensor on the Subaru/SCExAO testbed. Our system is stable out to around ±400 nm of low-order Zernike wave-front error and can correct petaling modes. When injecting ~30 nm rms of low-order time-varying error, we achieve ~10× rejection at 1 s timescales; further refinements to the control law and lantern fabrication process should make sub-nanometric wave-front control possible. In the future, novel sensors like the PL wave-front sensor may prove to be critical in resolving the wave-front control challenges posed by exoplanet direct imaging.

Keywords: Astronomical instrumentation, Adaptive optics
Time-variable Jet Ejections from RW Aur A, RY Tau, and DG Tau. We present Gemini-NIFS, Very Large Telescope-SINFONI, and Keck-OSIRIS observations of near-IR [Fe II] emission that are associated with well-studied jets from three active T Tauri stars-RW Aur A, RY Tau, and DG Tau-taken from 2012 to 2021. We primarily cover the redshifted jet from RW Aur A and the blueshifted jets from RY Tau and DG Tau, in order to investigate long-term time variabilities that are potentially related to the activities of mass accretion and/or the stellar magnetic fields. All of these jets consist of several moving knots, with tangential velocities of 70-240 km s-1, which were ejected from the star with different velocities and at irregular time intervals. Via comparisons with the literature, we identify significant differences in the tangential velocities between 1985-2008 and 2008-2021 for the DG Tau jet. The sizes of the individual knots appear to increase with time, and, in turn, their peak brightnesses in the 1.644 μm emission decreased by up to a factor of ~30 during the epochs of our observations. The variety of decay timescales measured in the [Fe II] 1.644 μm emission could be attributed to different preshock conditions should the moving knots be unresolved shocks. However, our data do not exclude the possibility that these knots are due to nonuniform density/temperature distributions with another heating mechanism, or, in some cases, due to stationary shocks without proper motions. Spatially resolved observations of these knots with significantly higher angular resolutions will be necessary to better understand their physical nature. * Based on observations obtained at the Gemini Observatory, the European Southern Observatory (under ESO program 2100.C-5015), and the W. M. Keck Observatory.

Keywords: T Tauri stars, Stellar jets
Pulsar-candidate Selection Using a Generative Adversarial Network and ResNeXt. Pulsar research has been a hot topic in the area of astronomy since they were first discovered. Pulsar discovery is fundamental for pulsar research. While pulsars are now visible across the electromagnetic spectrum, pulsar searches with modern radio telescopes are most promising. As the performance of astronomical instruments improves, the number of pulsar candidates detected by modern radio telescopes grows at an exponential rate. The application of artificial intelligence to the field of pulsar-candidate identification can automatically and efficiently address the identification problem with enormous amounts of data. However, there are still significant challenges in enhancing the accuracy of deep-learning-based pulsar-candidate identification. These problems result primarily from the fact that real pulsar data is scarce: the number of candidates that can be successfully identified as real pulsars (positive samples) is much smaller than those candidates that turn out to not be pulsars but instead radio-frequency interference or noise (negative samples). This makes it difficult to train a machine-learning model that can accurately select those candidates that are real pulsars. Therefore a novel pulsar-candidate identification framework is proposed that combines a deep convolutional generative adversarial neural network (DCGAN) and a deep aggregation residual network (ResNeXt). To overcome sample imbalance, the DCGAN is utilized to generate images that approximate real pulsars, while observed and generated candidates are employed together to train the pulsar-candidate identification model ResNeXt. Experiments on the HTRU Medlat data set back up the framework's performance. The precision, recall, and F1-score of the framework are 100%.

Keywords: Astronomy data analysis, Pulsars
A Scheme of Full Kinetic Particle-in-cell Algorithms for GPU Acceleration Using CUDA Fortran Programming. The emerging computable devices, graphical processing units (GPUs), are gradually applied in the simulations of space physics. In this paper, we introduce an approach that implements full kinetic particle-in-cell simulations on GPU architecture devices using the CUDA Fortran language programming for the first time. Using the latest high-performance computing NVIDIA GPUs, this program, which follows the second-order leap-frog iteration method, can speed up the computing process by a factor of 150-285 on a single device compared with the time cost of running with a single core of an Intel Xeon Gold processor. Our scheme improves fast accessibility to the simulation results and provides valuable assistance in studying the physical process.

Keywords: GPU computing, Solar magnetic reconnection
A Catalog of Candidate Double and Lensed Quasars from Gaia and WISE Data. Making use of strong correlations between closely separated multiple or double sources and photometric and astrometric metadata in Gaia Early Data Release 3 (EDR3), we generate a catalog of candidate double- and multiply imaged lensed quasars and active galactic nuclei (AGNs), comprising 3140 systems. It includes two partially overlapping parts: a sample of distant (redshifts mostly greater than 1) sources with perturbed data; and systems that have been resolved into separate components by Gaia at separations less than 2″. For the first part, which is roughly one-third of the published catalog, we synthesized 0.617 million redshifts using multiple machine-learning prediction and classification methods, using independent photometric and astrometric data from Gaia EDR3 and the Wide-field Infrared Survey Explorer, with accurate spectroscopic redshifts from the Sloan Digital Sky Survey (SDSS) as a training set. Using these synthetic redshifts, we estimate a 4.9% rate of interlopers with spectroscopic redshifts below 1 in this part of the catalog. Unresolved candidate double and dual AGNs and quasars are selected as sources with a marginally high BP/RP excess factor (phot_bp_rp_excess_factor), which is sensitive to source extent, limiting our search to high-redshift quasars. For the second part of the catalog, additional filters on measured parallax and near-neighbor statistics are applied to diminish the propagation of the remaining stellar contaminants. The estimated rate of the positives (double or multiple sources) is 98%, and the estimated rate of dual (physically related) quasars is greater than 54%. A few dozen serendipitously found objects of interest are discussed in more detail, including known and new lensed images, planetary nebulae, young IR stars of peculiar morphology, and quasars with catastrophic redshift errors in SDSS.

Keywords: Double quasars, Active galactic nuclei, Astrometry, Gaia