Sazuna/UAT_keywords huggingface dataset:
Simulations of Prominence Eruption Preceded by Large-amplitude Longitudinal Oscillations and Draining. We present magnetohydrodynamic (MHD) simulations of the evolution from quasi-equilibrium to eruption of a prominence-forming twisted coronal flux rope under a coronal streamer. We have compared the cases with and without the formation of prominence condensations, as well as the case where prominence condensations form but we artificially initiate the draining of the prominence. We find that the prominence weight has a significant effect on the stability of the flux rope and can significantly increase the loss-of-equilibrium height. The flux rope can be made to erupt earlier by initiating draining of the prominence mass. We have also performed a simulation where large-amplitude longitudinal oscillations of the prominence are excited during the quasi-static phase. We find that the gravity force along the magnetic field lines is the major restoring force for the oscillations, in accordance with the "pendulum model," although the oscillation periods are higher (by about 10%-40%) than estimated from the model because of the dynamic deformation of the field line dips during the oscillations. The oscillation period is also found to be slightly smaller for the lower part of the prominence in the deeper dips compared to the upper part in the shallower dips. The oscillations are quickly damped out after about two to three periods and are followed by prominence draining and the eventual eruption of the prominence. However, we do not find a significant enhancement of the prominence draining and earlier onset of eruption with the excitation of the prominence oscillations compared to the case without.

Keywords: Magnetohydrodynamics, Solar prominences, Solar filament eruptions, Solar coronal mass ejections, Magnetohydrodynamical simulations
Local Simulations of Spiral Galaxies with the TIGRESS Framework. I. Star Formation and Arm Spurs/Feathers. Spiral arms greatly affect gas flows and star formation in disk galaxies. We use local three-dimensional simulations of the vertically stratified, self-gravitating, differentially rotating interstellar medium (ISM) subject to a stellar spiral potential to study the effects of spiral arms on star formation and formation of arm spurs/feathers. We adopt the TIGRESS framework of Kim &amp; Ostriker to handle radiative heating and cooling, star formation, and ensuing supernova (SN) feedback. We find that more than 90% of star formation takes place in spiral arms, but the global star formation rate (SFR) in models with spiral arms is enhanced by less than a factor of 2 compared to the no-arm counterpart. This results from a quasi-linear relationship between the SFR surface density ${{\rm{\Sigma }}}_{\mathrm{SFR}}$ and the gas surface density Σ, and supports the picture that spiral arms do not trigger star formation but rather concentrate star-forming regions. Correlated SN feedback produces gaseous spurs/feathers downstream from arms in both magnetized and unmagnetized models. These spurs/feathers are short lived and have magnetic fields parallel to their length, in contrast to the longer-lived features with perpendicular magnetic fields induced by gravitational instability. SN feedback drives the turbulent component of magnetic fields, with the total magnetic field strength sublinearly proportional to Σ. The total midplane pressure varies by a factor of ∼10 between arm and interarm regions but agrees locally with the total vertical ISM weight, while ${{\rm{\Sigma }}}_{\mathrm{SFR}}$ is locally consistent with the prediction of pressure-regulated, feedback-modulated theory.

Keywords: AGN host galaxies, Galaxy magnetic fields, Disk galaxies, Spiral galaxies, Star formation, Interstellar medium, Superbubbles, Magnetohydrodynamical simulations
Dual-wavelength ALMA Observations of Dust Rings in Protoplanetary Disks. We present new Atacama Large Millimeter/submillimeter Array observations for three protoplanetary disks in Taurus at 2.9 mm and comparisons with previous 1.3 mm data both at an angular resolution of ∼0"1 (15 au for the distance of Taurus). In the single-ring disk DS Tau, double-ring disk GO Tau, and multiring disk DL Tau, the same rings are detected at both wavelengths, with radial locations spanning from 50 to 120 au. To quantify the dust emission morphology, the observed visibilities are modeled with a parametric prescription for the radial intensity profile. The disk outer radii, taken as 95% of the total flux encircled in the model intensity profiles, are consistent at both wavelengths for the three disks. Dust evolution models show that dust trapping in local pressure maxima in the outer disk could explain the observed patterns. Dust rings are mostly unresolved. The marginally resolved ring in DS Tau shows a tentatively narrower ring at the longer wavelength, an observational feature expected from efficient dust trapping. The spectral index (αmm) increases outward and exhibits local minima that correspond to the peaks of dust rings, indicative of the changes in grain properties across the disks. The low optical depths (τ ∼ 0.1-0.2 at 2.9 mm and 0.2-0.4 at 1.3 mm) in the dust rings suggest that grains in the rings may have grown to millimeter sizes. The ubiquitous dust rings in protoplanetary disks modify the overall dynamics and evolution of dust grains, likely paving the way toward the new generation of planet formation.

Keywords: Circumstellar dust, Pre-main sequence stars, Protoplanetary disks, Planet formation
A Supernova Candidate at z = 0.092 in XMM-Newton Archival Data. During a search for X-ray transients in the XMM-Newton archive within the EXTraS project, we discovered a new X-ray source that is detected only during an ∼5 min interval of an ∼21 hr-long observation performed on 2011 June 21 (EXMM 023135.0-603743, probability of a random Poissonian fluctuation: ∼1.4 × 10-27). With dedicated follow-up observations, we found that its position is consistent with a star-forming galaxy (SFR = 1-2 M☉ yr-1) at redshift z = 0.092 ± 0.003 (d = 435 ± 15 Mpc). At this redshift, the energy released during the transient event was 2.8 × 1046 erg in the 0.3-10 keV energy band (in the source rest frame). The luminosity of the transient, together with its spectral and timing properties, make EXMM 023135.0-603743 a gripping analog to the X-ray transient associated to SN 2008D, which was discovered during a Swift/XRT observation of the nearby (d = 27 Mpc) supernova-rich galaxy NGC 2770. We interpret the XMM-Newton event as a supernova shock break-out or an early cocoon, and show that our serendipitous discovery is broadly compatible with the rate of core-collapse supernovae derived from optical observations and much higher than that of tidal disruption events.

Keywords: X-ray bursts, X-ray observatories, Core-collapse supernovae
Timing the Pulsations of the Accreting Millisecond Pulsar SAX J1808.4-3658 during Its 2019 Outburst. In this paper we present a coherent timing analysis of the 401 Hz pulsations of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during its 2019 outburst. Using observations collected with the Neutron Star Interior Composition Explorer (NICER), we establish the pulsar spin frequency and orbital phase during its latest epoch. We find that the 2019 outburst shows a pronounced evolution in pulse phase over the course of the outburst. These phase shifts are found to correlate with the source flux and are interpreted in terms of hot-spot drift on the stellar surface, driven by changes in the mass accretion rate. Additionally, we find that the long-term evolution of the pulsar spin frequency shows evidence for a modulation at the Earth's orbital period, allowing for pulsar timing based astrometry of this accreting millisecond pulsar.

Keywords: Low-mass x-ray binary stars, Millisecond pulsars
Assembly Conformity of Structure Growth: Fossil versus Normal Groups of Galaxies. Using a semianalytic method calibrated to the global star formation history and the stellar mass function at z = 0, we attempt to understand the most stellar-deficient galaxy groups. We argue that such groups are a kind of fossil group (FGs)—in comparison to the normal groups of galaxies, they assemble both halo and stellar mass earlier. We find that there is a central galaxy and satellite conformity between these FGs and normal groups: centrals and satellites in the former form earlier and are more stellar deficient than the counterparts of the latter. We term this effect "assembly conformity" of dark matter halos. This effect accounts for about 70% of the difference in stellar content between FGs and normal groups. When split by the peak redshift for the star formation rate of a group, the mass functions of satellite halos on either side of the peak redshift are found to be indistinguishable between FGs and normal groups, indicating a self-similarity of halo assembly with respect to the peak. The "baryonic environmental" effect due to ram pressure and gas heating accounts for about 30% of the difference in stellar content. While the total stellar mass of FGs is lower than that of normal groups, we predict that the mass of the brightest central galaxy of FGs is, on average, higher than that of normal groups. We also predict that in the central galaxies of FGs, there is a negative stellar age gradient from the center outward, where the opposite is expected for those in normal groups.

Keywords: Galaxy formation, Galaxy groups
The R-Process Alliance: A Very Metal-poor, Extremely r-process-enhanced Star with [Eu/Fe] = + 2.2, and the Class of r-III Stars. We report the discovery of J1521-3538, a bright (V = 12.2), very metal-poor ([Fe/H] = -2.8) strongly r-process-enhanced field horizontal branch star, based on a high-resolution, high signal-to-noise Magellan/MIKE spectrum. J1521-3538 shows the largest r-process element overabundance in any known r-process-enhanced star, with [Eu/Fe] = +2.2, and its chemical abundances of 22 neutron-capture elements closely match the scaled solar r-process pattern. J1521-3538 is also one of few known carbon-enhanced metal-poor stars with r-process enhancement (CEMP-r stars), as found after correcting the measured C abundance for the star's evolutionary status. We propose to extend the existing classification of moderately enhanced ( $+0.3\leqslant {\rm{[Eu/Fe]}}\leqslant +1.0$ ) r-I and strongly r-process enhanced ( ${\rm{[Eu/Fe]}}\gt +1.0$ ) r-II stars to include an r-III class, for r-process stars such as J1521-3538, with ${\rm{[Eu/Fe]}}\gt +2.0$ and ${\rm{[Ba/Eu]}}\lt -0.5$ , or $\geqslant 100$ times the solar ratio of europium to iron. Using cosmochronometry, we estimate J1521-3538 to be $12.5\pm 5\,\mathrm{Gyr}$ and $8.9\pm 5\,\mathrm{Gyr}$ , using two different sets of initial production ratios. These ages are based on measurements of the Th line at 4019 Å and other r-process element abundances. This is broadly consistent with the old age of a low-mass, metal-poor field red horizontal branch star. J1521-3538 likely originated in a low-mass dwarf galaxy that was later accreted by the Milky Way, as evidenced by its highly eccentric orbit. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Based on observations obtained at the Gemini Observatory (Prop. IDs: GS-2015A-Q-205), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the NSF (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil). Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program(s) 092.D-0308(A).

Keywords: Stellar abundances, Milky Way stellar halo, Population II stars, Nucleosynthesis
Investigating the Physical Conditions in Extended System Hosting Mid-infrared Bubble N14. To observationally explore physical processes, we present a multiwavelength study of a wide-scale environment toward l = 13°7-14°9 containing a mid-infrared bubble N14. The analysis of 12CO, 13CO, and C18O gas at [31.6, 46] km s-1 reveals an extended physical system (extension ∼59 pc × 29 pc), which hosts at least five groups of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) 870 μm dust clumps at d ∼3.1 kpc. These spatially distinct groups/subregions contain unstable molecular clumps and are associated with several Class I young stellar objects (mean age ∼0.44 Myr). At least three groups of ATLASGAL clumps associated with the expanding H II regions (including the bubble N14) and embedded infrared dark clouds, devoid of the ionized gas, are found in the system. The observed spectral indices derived using the Giant Metrewave Radio Telescope (GMRT) and THOR radio continuum data suggest the presence of nonthermal emission with the H II regions. The high-resolution GMRT radio continuum map at 1280 MHz traces several ionized clumps powered by massive B-type stars toward N14, which are considerably young (age ∼103-104 yr). Locally, the early stage of star formation is evident toward all the groups of clumps. The position-velocity maps of 12CO, 13CO, and C18O exhibit an oscillatory-like velocity pattern toward the selected longitude range. Considering the presence of different groups/subregions in the system, the oscillatory pattern in velocity is indicative of the fragmentation process. All these observed findings favor the applicability of the global collapse scenario in the extended physical system, which also seems to explain the observed hierarchy.

Keywords: Star formation, Pre-main sequence stars, H II regions, Interstellar medium
Peculiar Prompt Emission and Afterglow in the H.E.S.S.-detected GRB 190829A. We present the results of a detailed investigation of the prompt and afterglow emission in the High Energy Stereoscopic System (H.E.S.S.)-detected GRB 190829A. Swift and Fermi observations of the prompt phase of this gamma-ray burst (GRB) reveal two isolated subbursts or episodes, separated by a quiescent phase. The energetic and the spectral properties of the first episode are in stark contrast to the second. The first episode, which has a higher spectral peak ∼120 keV and a low isotropic energy ∼1050 erg is an outlier to the Amati correlation and marginally satisfies the Yonetoku correlation. However, the energetically dominant second episode has lower peak energy and is consistent with the above correlations. We compared this GRB to other low-luminosity GRBs (LLGRBs). Prompt emission of LLGRBs also indicates a relativistic shock breakout origin of the radiation. For GRB 190829A, some of the properties of a shock breakout origin are satisfied. However, the absence of an accompanying thermal component and energy above the shock breakout critical limit precludes a shock breakout origin. In the afterglow, an unusual long-lasting late-time flare of duration ∼104 s is observed. We also analyzed the late-time Fermi Large Area Telescope (LAT) emission that encapsulates the H.E.S.S. detection. Some of the LAT photons are likely to be associated with the source. All of the above observational facts suggest GRB 190829A is a peculiar low-luminosity GRB that is not powered by a shock breakout, and has an unusual rebrightening due to patchy emission or a refreshed shock during the afterglow. Furthermore, our results show that teraelectronvolt-energy photons seem common in both high-luminosity GRBs and LLGRBs.

Keywords: Burst astrophysics, Gamma-ray bursts, High energy astrophysics
Spectra of Diffusion, Dispersion, and Dissipation for Kinetic Alfvénic and Compressive Turbulence: Comparison between Kinetic Theory and Measurements from MMS. We analyze measurements from Magnetospheric Multiscale mission to provide the spectra related with diffusion, dispersion, and dissipation, all of which are compared with predictions from plasma theory. This work is one example of magnetosheath turbulence, which is complex and diverse and includes more wave modes than the kinetic Alfvénic wave (KAW) mode studied here. The counter-propagation of KAW is identified from the polarities of cross-correlation spectra: CC(Ne, ∣B∣), CC(Ve⊥, B⊥), CC(Ve∥, B∥), and CC(Ne, Ve∥). We propose the concepts of turbulence ion and electron diffusion ranges (T-IDRs and T-EDRs) and identify them practically based on the ratio between electric field power spectral densities in different reference frames: PSD( $\delta {{\boldsymbol{E}}}_{{\rm{i}},\mathrm{local}}^{{\prime} }$ )/PSD(δEglobal) and PSD( $\delta {{\boldsymbol{E}}}_{{\rm{e}},\mathrm{local}}^{{\prime} }$ )/PSD(δEglobal). The outer scales of the T-IDR and T-EDR are observed to be at the wavenumber of kdi ∼ 0.2 and kde ∼ 0.1, where di and de are the proton and electron inertial lengths, respectively. The signatures of positive dispersion related to the Hall effect are illustrated observationally and reproduced theoretically with flat PSD(δEglobal) and steep PSD(δB), as well as a bifurcation between PSD(δVi) and PSD(δVe). We calculate the dissipation rate spectra, $\gamma \left(k\right)$ , which clearly show the commencement of dissipation around kdi ∼ 1. We find that the dissipation in this case is mainly converted to electron parallel kinetic energy, responsible for the electron thermal anisotropy with Te,∥/Te,⊥ &gt; 1. The "3D" (diffusion, dispersion, and dissipation) characteristics of kinetic Alfvénic and compressive plasma turbulence are therefore summarized as follows: positive dispersion due to the Hall effect appears in the T-IDR, while dominant parallel dissipation with energy transferred to electrons occurs mainly in the T-EDR.

Keywords: Interplanetary turbulence, Solar wind, Alfven waves
Consistently Simulating a Wide Range of Atmospheric Scenarios for K2-18b with a Flexible Radiative Transfer Module. The atmospheres of small, potentially rocky exoplanets are expected to cover a diverse range in composition and mass. Studying such objects therefore requires flexible and wide-ranging modeling capabilities. We present in this work the essential development steps that lead to our flexible radiative transfer module, REDFOX, and validate REDFOX for the solar system planets Earth, Venus, and Mars, as well as for steam atmospheres. REDFOX is a k-distribution model using the correlated-k approach with the random overlap method for the calculation of opacities used in the δ-two-stream approximation for radiative transfer. Opacity contributions from Rayleigh scattering, UV/visible cross sections, and continua can be added selectively. With the improved capabilities of our new model, we calculate various atmospheric scenarios for K2-18b, a super-Earth/sub-Neptune with ∼8 M⊕ orbiting in the temperate zone around an M star, with recently observed H2O spectral features in the infrared. We model Earth-like, Venus-like, and H2-He primary atmospheres of different solar metallicity and show resulting climates and spectral characteristics compared to observed data. Our results suggest that K2-18b has an H2-He atmosphere with limited amounts of H2O and CH4. Results do not support the possibility of K2-18b having a water reservoir directly exposed to the atmosphere, which would reduce atmospheric scale heights, and with it the amplitudes of spectral features, making the latter inconsistent with the observations. We also performed tests for H2-He atmospheres up to 50 times solar metallicity, all compatible with the observations.

Keywords: Extrasolar rocky planets, Exoplanets, Super Earths, Planetary atmospheres, Mini Neptunes, Computational methods, Radiative transfer, Radiative transfer simulations, Exoplanet atmospheres
MOSEL: Strong [OIII] 5007 Å Emitting Galaxies at (3 &lt; z &lt; 4) from the ZFOURGE Survey. To understand how strong emission-line galaxies (SELGs) contribute to the overall growth of galaxies and star formation history of the universe, we target SELGs from the ZFOURGE imaging survey that have blended Hβ+[O III] rest-frame equivalent widths of &gt;230 Å and 2.5 &lt; ${z}_{\mathrm{phot}}$ &lt; 4.0. Using Keck/MOSFIRE, we measure 49 redshifts for galaxies brighter than Ks = 25 mag as part of our Multi-Object Spectroscopic Emission Line (MOSEL) survey. Our spectroscopic success rate is ∼53% and ${z}_{\mathrm{phot}}$ uncertainty is ${\sigma }_{z}$ = [Δz/(1+z)] = 0.0135. We confirm 31 ELGs at $3\lt {z}_{\mathrm{spec}}\lt 3.8$ , and show that SELGs have spectroscopic rest-frame [O III]5007 Å equivalent widths of 100-500 Å and tend to be lower-mass systems [ $\mathrm{log}({M}_{\star }/{M}_{\odot })$ ∼ 8.2-9.6] compared with more typical star-forming galaxies. The SELGs lie ∼0.9 dex above the star-forming main sequence at z ∼ 3.5 and have high inferred gas fractions of ${f}_{\mathrm{gas}}$ ≳ 60%, i.e., the inferred gas masses can easily fuel a starburst to double stellar masses within ∼10-100 Myr. Combined with recent results using ZFOURGE, our analysis indicates that (1) strong [O III]5007 Å emission signals an early episode of intense stellar growth in low-mass [ ${M}_{\star }\lt 0.1\,{M}^{\star }$ ] galaxies and (2) many, if not most, galaxies at z &gt; 3 go through this starburst phase. If true, low-mass galaxies with strong [O III]5007 Å emission (EWrest &gt; 200 Å) may be an increasingly important source of ionizing UV radiation at z &gt; 3.

Keywords: Starburst galaxies, Galaxy formation, Galaxy properties, Emission line galaxies, Galaxy evolution, Near infrared astronomy
Near-infrared Search for Fundamental-mode RR Lyrae Stars toward the Inner Bulge by Deep Learning. Aiming to extend the census of RR Lyrae stars to highly reddened low-latitude regions of the central Milky Way, we performed a deep near-IR variability search using data from the VISTA Variables in the Vía Láctea (VVV) survey of the bulge, analyzing the photometric time series of over a hundred million point sources. In order to separate fundamental-mode RR Lyrae (RRab) stars from other periodically variable sources, we trained a deep bidirectional long short-term memory recurrent neural network (RNN) classifier using VVV survey data and catalogs of RRab stars discovered and classified by optical surveys. Our classifier attained a ∼99% precision and recall for light curves with signal-to-noise ratio above 60, and is comparable to the best-performing classifiers trained on accurate optical data. Using our RNN classifier, we identified over 4300 hitherto unknown bona fide RRab stars toward the inner bulge. We provide their photometric catalog and VVV $J,H,{K}_{s}$ photometric time series.

Keywords: Light curve classification , Neural networks, Surveys, RR Lyrae variable stars, Catalogs, Near infrared astronomy