Sazuna/UAT_keywords huggingface dataset:
MINDS. JWST-MIRI Observations of a Spatially Resolved Atomic Jet and Polychromatic Molecular Wind toward SY Cha. The removal of angular momentum from protostellar systems drives accretion onto the central star and may drive the dispersal of the protoplanetary disk. Winds and jets can contribute to removing angular momentum from the disk, though the dominant process remains unclear. To date, observational studies of resolved disk winds have mostly targeted highly inclined disks. We report the detection of extended H2 and [Ne II] emission toward the young stellar object SY Cha with the JWST Mid-InfraRed Instrument Medium-Resolution Spectrometer (MIRI-MRS). This is one of the first polychromatic detections of extended H2 toward a moderately inclined, i = 51 1, Class II source. We measure the semiopening angle of the H2 emission and build a rotation diagram to determine the H2 excitation temperature and abundance. We find a wide semiopening angle, high temperature, and low column density for the H2 emission, all of which are characteristic of a disk wind. We derive a molecular wind mass loss rate of 3 ± 2 × 10‑9 M⊙ yr‑1, which is high compared to the previously derived stellar accretion rate of 6.6 × 10‑10 M⊙ yr‑1. This suggests either that the stellar accretion and the disk wind are driven by different mechanisms or that accretion onto the star is highly variable. These observations demonstrate MIRI-MRS's utility in expanding studies of resolved disk winds beyond edge-on sources.

Keywords: Molecular gas, Stellar jets, Protoplanetary disks, Infrared spectroscopy
Stability and Convergence of Nuclear Detonations in White Dwarf Collisions. We investigate the numerical stability of thermonuclear detonations in 1D accelerated reactive shocks and 2D binary collisions of equal-mass magnetized and unmagnetized white dwarf stars. To achieve high resolution at initiation sites, we devised geometric gridding and mesh velocity strategies specially adapted to the unique requirements of head-on collisional geometries, scenarios in which one expects maximum production of iron-group products. We study the effects of grid resolution and the limiting of temperature, energy generation, and reactants for different stellar masses, separations, magnetic fields, initial compositions, detonation mechanisms, and limiter parameters across a range of cell sizes from 1 to 100 km. Our results set bounds on the parameter space of limiter amplitudes for which both temperature- and energy-limiting procedures yield consistent and monotonically convergent solutions. Within these bounds, we find that grid resolutions of 5 km or better are necessary for uncertainties in total released energy and iron-group products to drop below 10%. Intermediate-mass products (e.g., calcium) exhibit similar convergence trends but with somewhat greater uncertainty. These conclusions apply equally to pure C/O white dwarfs, multispecies compositions (including helium shells), magnetized and unmagnetized cores, and either single or multiple detonation scenarios.

Keywords: White dwarf stars, Nuclear astrophysics
Semianalytical Fokker─Planck Models for Nuclear Star Clusters. We study the dynamics of nuclear star clusters, the dense stellar environments surrounding massive black holes in the centers of galaxies. We consider angular momentum diffusion due to two-body scatterings among stellar objects and energy advection due to gravitational-wave emission upon interaction with the central massive black hole. Such dynamics are described by a 2D Fokker─Planck (FP) equation in energy─angular momentum space. Focusing on the transition between the diffusion-dominated region and the advection-dominated one, we utilize self-similarity to obtain a full solution for the steady-state FP equation. This solution provides the density and flux of the stellar objects in nuclear star clusters. This improves the rate estimates for extreme-mass ratio inspirals, and has interesting implications for a new class of galactic center transients called quasiperiodic eruptions.

Keywords: Supermassive black holes, Stellar mass black holes, Stellar dynamics, Gravitational wave sources, Galaxy nuclei, X-ray transient sources
Magnetorotational Instability in Collisional Weakly Ionized Plasma with Distinct Species Velocities. In a differential rotating system, we use the incompressible multifluid model to investigate the dynamics of a weakly ionized plasma placed in a vertical background magnetic field with radial shearing. The equilibrium current is taken into account. The differences in velocities between charged species and neutrals are supposed to be related to the collisions. The analytical expression of the general local dispersion relation is derived and the effect of the shearing magnetic field is demonstrated in three different limiting cases. Momentum transfer to neutrals is neglected in the first case, and the instability criteria are provided with the involvement of magnetic field shearing. In the magnetohydrodynamic (MHD) case, the previous results are reproduced when setting the equilibrium current density to zero, and the magnetic field structure is depicted to restrain/reinforce the instability in the Keplerian system with decaying/increasing shearing. In the last case, the finite collisions with weak ionization and ion Hall effects generate another unstable vertical mode compared with the MHD case and also alleviate the unstable waves propagated between the horizontal and vertical directions.

Keywords: Magnetohydrodynamics
Blowin' in the Nonisothermal Wind: Core-powered Mass Loss with Hydrodynamic Radiative Transfer. The mass loss rates of planets undergoing core-powered escape are usually modeled using an isothermal Parker-type wind at the equilibrium temperature, Teq. However, the upper atmospheres of sub-Neptunes may not be isothermal if there are significant differences between the opacity to incident visible and outgoing infrared radiation. We model bolometrically driven escape using AIOLOS, a hydrodynamic radiative-transfer code that incorporates double-gray opacities, to investigate the process's dependence on the visible-to-infrared opacity ratio, γ. For a value of γ ≈ 1, we find that the resulting mass loss rates are well approximated by a Parker-type wind with an isothermal temperature T = Teq/21/4. However, we show that over a range of physically plausible values of γ, the mass loss rates can vary by orders of magnitude, ranging from 10‑5× the isothermal rate for low γ to 105× the isothermal rate for high γ. The differences in mass loss rates are largest for small planet radii, while for large planet radii, mass loss rates become nearly independent of γ and approach the isothermal approximation. We incorporate these opacity-dependent mass loss rates into a self-consistent planetary mass and energy evolution model and show that lower/higher γ values lead to more/less hydrogen being retained after core-powered mass loss. In some cases, the choice of opacities determines whether or not a planet can retain a significant primordial hydrogen atmosphere. The dependence of escape rate on the opacity ratio may allow atmospheric escape observations to directly constrain a planet's opacities and therefore its atmospheric composition.

Keywords: Hydrodynamical simulations, Atmospheric structure, Radiative transfer, Exoplanet atmospheric evolution, Exoplanet atmospheres, Exoplanet atmospheric structure
Multiwavelength Variability Analysis of the Blazar PKS 0727-11: An ~ 168 day Quasiperiodic Oscillation in the γ-Ray. We performed variability analysis of the multiwavelength light curves (LCs) for the flat-spectrum radio quasar PKS 0727-11. Using the generalized Lomb–Scargle periodogram, we identified a possible quasiperiodic oscillation (QPO) of ~168.6 days (persisted for six cycles, with a significance of 3.8σ) in the γ-ray LC during the flare period (MJD 54687–55738). It is the first time that periodic variations have been detected in this source, and further supported by other methods: weighted wavelet z-transform, phase dispersion minimization, REDFIT, autoregressive integrated moving average model, and structure function analysis. Cross-correlation analysis shows that there is a strong correlation between multiband light variations, indicating that γ-ray and radio flares may originate from the same disturbance, and the distance between the emission regions of γ-ray and radio flares is calculated based on the time lag. We demonstrate that QPO arising from the non-ballistic helical jet motion driven by the orbital motion in a supermassive binary black hole is a plausible physical explanation. In this scenario, the estimated mass of the primary black hole is M ∼ 3.66 × 108–5.79 × 109 M⊙.

Keywords: Blazars, Flat-spectrum radio quasars
Interstellar Pickup Ion Observations to 60 au. Prior to the Solar Wind Around Pluto (SWAP) observations from New Horizons, the only significant interstellar pickup ion (PUI) observations were taken inside 5.4 au from the Ulysses and 1 au missions. Here, we analyze SWAP data to provide the first comprehensive radial profile of interstellar PUIs in the outer heliosphere from ∼22 to 60 au. This study is the first to combine the low time resolution (one day) data inside 49.5 au with the high time resolution (half hour) data outside of that. We show that these two data sets can be reliably analyzed together in what is now a nearly continuous set of PUI observations. We derive radial gradients for all of the PUI parameters, as well as ratios to their solar wind counterparts from these combined data and extrapolate them out to a nominal termination shock distance at ∼90 au. We find that the fraction of PUIs to all ions in the solar wind continues to grow, reaching ∼18% by 60 au and extrapolated to be ∼30% at 90 au. The PUI internal pressure is ∼11% of the solar wind dynamic pressure at 60 au and expected to be ∼21% by 90 au. Such large values further highlight the importance of PUIs as the dominant driver of the physics of the outer heliosphere, as well as at the termination shock.

Keywords: Space plasmas, Interplanetary shocks, Heliosphere, Plasma physics, Solar wind, Pickup ions
Discovering Large-scale Structure at 2 &lt; z &lt; 5 in the C3VO Survey. The Charting Cluster Construction with VUDS and ORELSE (C3VO) survey is an ongoing imaging and spectroscopic campaign aiming to map out the growth of structure up to z ∼ 5 and was born from the combination of the Visible Multi-Object Spectrograph Ultra Deep Survey and the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. As we previously accomplished with the ORELSE survey, we apply our technique known as Voronoi tessellation Monte Carlo (VMC) mapping to search for serendipitous galaxy overdensities at 2 &lt; z &lt; 5 in the three C3VO fields. We also apply the same technique to mock observations of simulated galaxies with properties derived from the GAlaxy Evolution and Assembly semianalytic model in order to judge the effectiveness of our search algorithm as a function of redshift, total mass, and fraction of spectroscopic redshifts. We find completeness and purity values of the order of 30%─50% for   and 2 &lt; z &lt; 4, with a strong dependence on mass and redshift, with values as high as ∼80% and ∼70%, respectively, in the best-case scenario for  . In the C3VO fields, we were able to recover many of the previously known structures in the literature as well as find hundreds of new overdensity candidates, once again demonstrating the powerful capabilities of VMC mapping when applied to wide-field optical and infrared galaxy evolution surveys at ever higher redshifts.

Keywords: Galaxy clusters, Protoclusters, Galactic and extragalactic astronomy, Astronomical techniques, Galaxy groups, Spectroscopy, Photometry, Galaxy evolution
The Unique Helium Nova V445 Puppis Ejected ≫0.001 M<SUB>⊙</SUB> in the Year 2000 and Will Not Become a Type Ia Supernova. V445 Puppis (Nova Puppis 2000) is the only known example of a helium nova, where a layer of helium-rich gas accretes onto the surface of a white dwarf (WD) in a cataclysmic variable, with runaway helium burning making for the nova event. Speculatively, a helium nova can provide one path to produce a Type Ia supernova (SNIa), within the larger framework of single-degenerate models. Relatively little has been known about V445 Pup, with this work reporting the discovery of the orbital period near 1.87 days. The companion star is 2.65 ± 0.35 R⊙ in radius as an evolved giant star stripped of its outer hydrogen envelope. The orbital period immediately before the 2000 eruption was   = 1.871843 ± 0.000014 days, with a steady period change of (‑0.17 ± 0.06) × 10‑8 from 1896 to 1995. The period immediately after the nova eruption was Ppost = 1.873593 ± 0.000034 days, with a   of (‑4.7 ± 0.5) × 10‑8. The fractional orbital period change (ΔP/P) is +935 ± 27 ppm. This restricts the mass of the gases ejected in the nova eruption to be ≫0.001 M⊙, and much greater than the mass accreted to trigger the nova. So the WD is losing mass over each eruption cycle, and will not become a SNIa. Further, for V445 Pup and helium novae in general, I collect observations from 136 normal SNIa for which any giant or subgiant companion star would have been detected, yet zero companions are found. This is an independent proof that V445 Pup and helium novae are not SNIa progenitors.

Keywords: Supernova remnants, Cataclysmic variable stars, Type Ia supernovae, Classical novae
WALLABY Pilot Survey: Star Formation Enhancement and Suppression in Gas-rich Galaxy Pairs. Galaxy interactions can significantly affect the star formation in galaxies, but it remains a challenge to achieve a consensus on the star formation rate (SFR) enhancement in galaxy pairs. Here, we investigate the SFR enhancement of gas-rich galaxy pairs detected by the Widefield ASKAP L-band Legacy All-sky Blind surveY. We construct a sample of 278 paired galaxies spanning a stellar mass (M *) range from 107.6 to 1011.2 M ⊙. We obtain individual masses of atomic hydrogen (H I) for these paired galaxies using a novel deblending algorithm for H I data cubes. Quantifying the interaction stages and strengths with parameters motivated by first-principles analysis, we find that, at fixed stellar and H I mass, the alteration in the SFR of galaxy pairs starts when their dark matter halos are encountered. For galaxies with a stellar mass lower than 109 M ⊙, their SFRs show tentative suppression of 1.4σ after the halo encounter, and then become enhanced when their H I disks overlap, regardless of mass ratios. In contrast, the SFRs of galaxies with M * &gt; 109 M ⊙ increase monotonically toward smaller projected distances and radial velocity offsets. When a close companion is present, a pronounced SFR enhancement is found for the most H I-poor high-mass galaxies in our sample. Collecting the observational evidence, we provide a coherent picture of the evolution of galaxy pairs and discuss how the tidal effects and hydrodynamic processes shape the SFR enhancement. Our results provide a coherent picture of gas-rich galaxy interactions and impose constraints on the underlying physical processes.

Keywords: Galaxy interactions, Galaxy evolution, Galaxies, Interstellar atomic gas
X-Ray/Radio Quasiperiodic Pulsations Associated with Plasmoids in Solar Flare Current Sheets. Plasmoids (or magnetic islands) are believed to play an important role in the onset of fast magnetic reconnection and particle acceleration during solar flares and eruptions. Direct imaging of flare current sheets and the formation/ejection of multiple plasmoids in extreme-ultraviolet images, along with simultaneous X-ray and radio observations, offers significant insights into the mechanisms driving particle acceleration in solar flares. Here, we present direct imaging of the formation and ejection of multiple plasmoids in flare plasma/current sheets and the associated quasiperiodic pulsations (QPPs) observed at X-ray and radio wavelengths, using observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, RHESSI, and the Fermi Gamma-ray Burst Monitor. These plasmoids propagate bidirectionally upward and downward along the flare current sheet beneath the erupting flux rope during two successive flares associated with confined/failed eruptions. The flux rope exhibits evidence of helical kink instability, with the formation and ejection of multiple plasmoids in the flare current sheet, as predicted in an MHD simulation of a kink-unstable flux rope. RHESSI X-ray images show double coronal sources ("looptop" and higher coronal sources) located at both ends of the flare current/plasma sheet. Moreover, we detect an additional transient faint X-ray source (6–12 keV) located between the double coronal sources, which is cospatial with multiple plasmoids in the flare current sheet. X-ray (soft and hard) and radio (decimetric) observations unveil QPPs (periods ≈ 10 s and 100 s) associated with the ejection and coalescence of plasmoids. These observations suggest that energetic electrons are accelerated during the ejection and coalescence of multiple plasmoids in the flare current sheet.

Keywords: Solar corona, Solar coronal mass ejections, Solar flares, Solar magnetic reconnection
The Detection Rate of Associated Mg II Absorption Lines in Quasars Depends on Their Radio Emission. In active galactic nuclei, jet-driven feedback plays a significant role in influencing the properties of gas within their host galaxy and the circumgalactic medium. By combining observations from the Very Large Array Sky Survey, the Faint Images of the Radio Sky at Twenty-cm, the LOFAR Two Meter Sky Survey, and the Sloan Digital Sky Survey (SDSS), we assembled a sample of 3141 radio-loud quasars, among which 418 exhibit Mg II-associated absorption lines in their SDSS spectra. We classify these quasars into evolutionary stages based on their radio spectral shapes. Our analysis reveals that evolved quasars exhibit a significantly higher incidence of Mg II-associated absorption lines compared to younger sources, particularly among quasars with "nonpeaked" radio spectra, which show an incidence of Mg II-associated absorbers approximately 1.7 times greater than that of gigahertz-peaked spectrum sources. This observation can be explained effectively by jet-driven feedback. As quasars age, their jets expand and expel substantial amounts of gas from smaller scales to larger scales, ultimately reaching the circumgalactic medium. The gas expelled from the inner regions and distributed over larger scales results in a greater coverage fraction of absorbing gas. Consequently, evolved quasars exhibit a higher incidence of Mg II absorption lines.

Keywords: Radio loud quasars, Jets, Quasars
Detection of the Extended γ-Ray Emission around TeV Source 1LHAASO J0249+6022 with Fermi-LAT. 1LHAASO J0249+6022 is an extended very-high-energy γ-ray source discovered by the Large High-Altitude Air Shower Observatory. Based on nearly 16.1 yr of data from the Fermi Large Area Telescope, we report the probable γ-ray emission from 1LHAASO J0249+6022 in the 0.03–1 TeV energy range. The results show that its γ-ray spectrum can be well fitted by a single power law with an index of 1.54 ± 0.17, and integral photon flux is (4.28 ± 1.03) × 10‑11 photons cm‑2 s‑1. We also considered theoretically whether the nonthermal emission could originate from a pulsar wind nebula (PWN) scenario. Assuming that the particles injected into the nebula have a power-law distribution, the resulting spectrum from the inverse Compton scattering is consistent with the detected GeV and TeV γ-ray fluxes. Our study shows that the PWN scenario is reasonable for 1LHAASO J0249+6022.

Keywords: Gamma-ray astronomy, Astronomy data analysis, Spectral energy distribution, Pulsar wind nebulae
A Comprehensive Study of Type I (Thermonuclear) Bursts in the New Transient SRGA J144459.2–604207. We report an analysis of Insight-HXMT observations of the newly discovered accreting millisecond pulsar SRGA J144459.2–604207. During the outburst, detected in 2024 February by SRG/ART-XC, the broadband persistent spectrum was well fitted by an absorbed Comptonization model. We detected 60 type I X-ray bursts in the Insight-HXMT medium energy (ME) data, and 37 were also detected with the low-energy (LE) telescope. By superimposing the Insight-HXMT/LE/ME/HE light curves of 37 bursts with similar profiles and intensities, we measured a deficit of X-rays in the 40–70 keV energy band. By analyzing the time-resolved X-ray burst spectra, we determine the mean ratio of persistent to burst flux ofα = 71 ± 7. We estimate the average hydrogen mass fraction in the fuel at ignition, as  , and constrain the burst fuel composition as X0 ≲ 0.4. We found that 14 out of 60 X-ray bursts exhibited photospheric expansion, and thus we estimated the distance to the source as 10.03 ± 0.71 kpc. Combined with IXPE observations, the burst recurrence time increased from 1.55 to 8 hr as the local mass accretion rate decreased, which can be described as  .

Keywords: Low-mass x-ray binary stars, X-ray bursters
ASKAP Observations of the Radio Shell in the Composite Supernova Remnant G310.6-1.6. We report the observations of the radio shell of the supernova remnant (SNR) G310.6–1.6 at 943 MHz from the Evolutionary Map of the Universe (EMU) and the Polarization Sky Survey of the Universe's Magnetism (POSSUM) surveys by using the Australian Square Kilometre Array Pathfinder (ASKAP). We detect polarized emission from the central pulsar wind nebula (PWN) with rotation measures varying from –696 rad m‑2 to –601 rad m‑2. We measure the integrated flux density of the shell to be 36.4 ± 2.2 mJy at 943 MHz and derive a spectral index of αpwn = ‑0.4 ± 0.1 for the PWN and αshell = ‑0.7 ± 0.3 for the SNR shell. From the combined radio and X-ray observations, the object can be identified as a supernova explosion of about 2500 yr ago with an energy of about 1.3 × 1050 erg, suggesting an ejected mass of about 10 M⊙. The circular radio shell outside the circular hard X-ray shell is unique among Galactic SNRs. We discuss several possible scenarios, including blast wave, reverse shock, and pulsar-fed emission, but find that none of them can fully explain the observed characteristics of the shell. This poses a challenge for understanding the evolution of SNRs. The results of this paper demonstrate the potential of the ASKAP EMU and POSSUM surveys to discover more objects of small angular size and low surface brightness.

Keywords: Magnetic fields, Supernova remnants, Interstellar medium, Pulsar wind nebulae, Radio continuum emission, Polarimetry