Sazuna/UAT_keywords huggingface dataset:
Detailed Chemical Abundances of Star Clusters in the Large Magellanic Cloud. We derive the first detailed chemical abundances of three star clusters in the Large Magellanic Cloud (LMC), NGC 1831 (436 ± 22 Myr), NGC 1856 (350 ± 18 Myr), and [SL63]268 (1230 ± 62 Myr) using integrated-light spectroscopic observations obtained with the Magellan Echelle spectrograph on Magellan Baade telescope. We derive [Fe/H], [Mg/Fe], [Ti/Fe], [Ca/Fe], [Ni/Fe], [Mn/Fe], [Cr/Fe], and [Na/Fe] for the three clusters. Overall, our results match the LMC abundances obtained in the literature as well as those predicted by detailed chemical evolution models. For clusters NGC 1831 and NGC 1856, the [Mg/Fe] ratios appear to be slightly depleted compared with [Ca/Fe] and [Ti/Fe]. This could be hinting at the well-known Mg-Al abundance anti-correlation observed in several Milky Way globular clusters. We note, however, that higher signal-to-noise observations are needed to confirm such a scenario, particularly for NGC 1831. We also find a slightly enhanced integrated-light [Na/Fe] ratio for cluster [SL63]268 compared with those from the LMC field stars, possibly supporting a scenario of intracluster abundance variations. We stress that detailed abundance analysis of individual stars in these LMC clusters is required to confirm the presence or absence of multiple stellar populations.

Keywords: Large Magellanic Cloud, Galaxy chemical evolution, Star clusters
Quantifying the Magnetic Structure of a Coronal Shock Producing a Type II Radio Burst. Type II radio bursts are thought to be produced by shock waves in the solar atmosphere. However, what magnetic conditions are needed for the generation of type II radio bursts is still a puzzling issue. Here, we quantify the magnetic structure of a coronal shock associated with a type II radio burst. Based on multiperspective extreme-ultraviolet observations, we reconstruct the three-dimensional (3D) shock surface. By using a magnetic field extrapolation model, we then derive the orientation of the magnetic field relative to the normal of the shock front (θ Bn) and the Alfvén Mach number (M  A ) on the shock front. Combining the radio observations from the Nancay Radio Heliograph, we obtain the source region of the type II radio burst on the shock front. It is found that the radio burst is generated by a shock with M  A  ≳ 1.5 and a bimodal distribution of θ Bn. We also use the Rankine-Hugoniot relations to quantify the properties of the shock downstream. Our results provide a quantitative 3D magnetic structure condition of a coronal shock that produces a type II radio burst.

Keywords: Solar coronal mass ejection shocks, Shocks
Radiation-induced D/H Exchange Rate Constants in Aliphatics Embedded in Water Ice. Gas-phase and solid-state chemistry in low-temperature interstellar clouds and cores leads to a D/H enhancement in interstellar ices, which is eventually inherited by comets, meteorites, and even planetary satellites. Hence, the D/H ratio has been widely used as a tracer for the origins of extraterrestrial chemistry. However, the D/H ratio can also be influenced by cosmic rays, which are ubiquitous and can penetrate even dense interstellar molecular cores. The effects of such high-energy radiation on deuterium fractionation have not been studied in a quantitative manner. In this study, we present rate constants for radiation-induced D-to-H exchange for fully deuterated small (1-2 C) hydrocarbons embedded in H2O ice at 20 K and H-to-D exchange for the protiated forms of these molecules in D2O ice at 20 K. We observed larger rate constants for H-to-D exchange in the D2O ice versus D-to-H exchange in H2O ice, which we have attributed to the greater bond strength of C-D versus C-H. We find that the H-to-D exchange rate constants are smaller for protiated methane than ethane, in agreement with bond energies from the literature. We are unable to obtain rate constants for the unsaturated and reactive hydrocarbons ethylene and acetylene. Interpretation of the rate constants suggest that D/H exchange products are formed in abundance alongside radiolysis products. We discuss how our quantitative and qualitative data can be used to interpret the D/H ratios of aliphatic compounds observed throughout space.

Keywords: Ice destruction, Laboratory astrophysics, Solar system, Interstellar clouds, Cosmic rays
CHIPS: Complete History of Interaction-powered Supernovae. We present the public release of the Complete History of Interaction-Powered Supernovae (CHIPS) code, which is suited to model a variety of transients that arise from interaction with a dense circumstellar medium (CSM). Contrary to existing modelings, which mostly attach the CSM by hand, CHIPS self-consistently simulates both the creation of the CSM from mass eruption of massive stars prior to core collapse, and the subsequent supernova light curve. We demonstrate the performance of CHIPS by presenting examples of the density profiles of the CSM and the light curves. We show that the gross light-curve properties of putative interaction-powered transients (e.g., Type IIn supernovae, rapidly evolving transients and recently discovered fast blue optical transients) can be comprehensively explained with the output of CHIPS.

Keywords: Stellar mass loss, Circumstellar matter, Computational methods, Radiative transfer, Supernovae
Mid-infrared Studies of Dusty Sources in the Galactic Center. Mid-infrared (MIR) images of the Galactic center show extended gas and dust features along with bright infrared sources (IRS). Some of these dust features are a part of ionized clumpy streamers orbiting Sgr A*, known as the mini-spiral. We present their proper motions over a 12 yr time period and report their flux densities in N-band filters and derive their spectral indices. The observations were carried out by VISIR at the ESO's Very Large Telescope. High-pass filtering led to the detection of several resolved filaments and clumps along the mini-spiral. Each source was fit by a 2D Gaussian profile to determine the offsets and aperture sizes. We perform aperture photometry to extract fluxes in two different bands. We present the proper motions of the largest consistent set of resolved and reliably determined sources. In addition to stellar orbital motions, we identify a stream-like motion of extended clumps along the mini-spiral. We also detect MIR counterparts of the radio tail components of the IRS 7 source. They show a clear kinematical deviation with respect to the star. They likely represent Kelvin-Helmholtz instabilities formed downstream in the shocked stellar wind. We also analyze the shape and orientation of the extended late-type IRS 3 star that is consistent with the Atacama Large Millimeter/submillimeter Array submillimeter detection of the source. Its puffed-up envelope with a radius of ~2 × 106 R ☉ could be the result of the red-giant collision with a nuclear jet, which was followed by tidal prolongation along the orbit.

Keywords: Galactic center, Galaxy kinematics, Infrared photometry
Detection of a Prompt Fast-variable Thermal Component in the Multipulse Short Gamma-Ray Burst 170206A. We report the detection of a strong thermal component in the short gamma-ray burst 170206A with three intense pulses in its light curves, throughout which the fluxes of this thermal component exhibit fast temporal variability the same as that of the accompanying nonthermal component. The values of the time-resolved low-energy photon index in the nonthermal component are between about -0.79 and -0.16, most of which are harder than the -2/3 expected in the synchrotron emission process. In addition, we found a common evolution between the thermal component and the nonthermal component, ${E}_{{\rm{p}},\mathrm{CPL}}\propto {{kT}}_{\mathrm{BB}}^{0.95\pm 0.28}$ and ${F}_{\mathrm{CPL}}\propto {F}_{\mathrm{BB}}^{0.67\pm 0.18}$ , where E p,CPL and F CPL are the peak photon energy and corresponding flux of the nonthermal component, and kT BB and F BB are the temperature and corresponding flux of the thermal component, respectively. Finally, we proposed that the photospheric thermal emission and the Comptonization of thermal photons may be responsible for the observational features of GRB 170206A.

Keywords: Gamma-ray bursts, Astronomy data analysis
3D Radiative Transfer for Exoplanet Atmospheres. gCMCRT: A GPU-accelerated MCRT Code. Radiative transfer (RT) is a key component for investigating atmospheres of planetary bodies. With the 3D nature of exoplanet atmospheres being important in giving rise to their observable properties, accurate and fast 3D methods are required to be developed to meet future multidimensional and temporal data sets. We develop an open-source GPU RT code, gCMCRT, a Monte Carlo RT forward model for general use in planetary atmosphere RT problems. We aim to automate the post-processing pipeline, starting from direct global circulation model (GCM) output to synthetic spectra. We develop albedo, emission, and transmission spectra modes for 3D and 1D input structures. We include capability to use correlated-k and high-resolution opacity tables, the latter of which can be Doppler-shifted inside the model. We post-process results from several GCM groups, including ExoRad, SPARC/MITgcm THOR, UK Met Office UM, Exo-FMS, and the Rauscher model. Users can therefore take advantage of desktop and HPC GPU computing solutions. gCMCRT is well suited for post-processing large GCM model grids produced by members of the community and for high-resolution 3D investigations.

Keywords: High resolution spectroscopy, Hot Jupiters, Radiative transfer, Exoplanet atmospheres
Magnetization of Relativistic Current-carrying Jets with Radial Velocity Shear. Astrophysical jets, launched from the immediate vicinity of accreting black holes, carry away large amounts of power in a form of bulk kinetic energy of jet particles and electromagnetic flux. Here we consider a simple analytical model for relativistic jets at larger distances from their launching sites, assuming a cylindrical axisymmetric geometry with a radial velocity shear, and purely toroidal magnetic field. We argue that as long as the jet plasma is in magnetohydrostatic equilibrium, such outflows tend to be particle dominated, i.e., the ratio of the electromagnetic to particle energy flux, integrated over the jet cross-sectional area, is typically below unity, σ &lt; 1. At the same time, for particular magnetic and radial velocity profiles, magnetic pressure may still dominate over particle pressure for certain ranges of the jet radius, i.e., the local jet plasma parameter β pl &lt; 1, and this may be relevant in the context of particle acceleration and production of high-energy emission in such systems. The jet magnetization parameter can be elevated up to the modest values of $\sigma \lesssim { \mathcal O }(10)$ only in the case of extreme gradients or discontinuities in the gaseous pressure, and a significantly suppressed velocity shear. Such configurations, which consist of a narrow, unmagnetized jet spine surrounded by an extended, force-free layer, may require an additional poloidal field component to stabilize them against current-driven oscillations, but even this will not substantially elevate their σ parameter.

Keywords: Magnetohydrodynamics, Jets, Plasma jets
Convective Penetration in Early-type Stars. Observations indicate that the convective cores of stars must ingest a substantial amount of material from the overlying radiative zone, but the extent of this mixing and the mechanism that causes it remain uncertain. Recently, Anders et al. developed a theory of convective penetration and calibrated it with 3D numerical hydrodynamics simulations. Here we employ that theory to predict the extent of convective boundary mixing (CBM) in early-type main-sequence stars. We find that convective penetration produces enough mixing to explain core masses inferred from asteroseismology and eclipsing binary studies, and matches observed trends in mass and age. While there are remaining uncertainties in the theory, this agreement suggests that most CBM in early-type main-sequence stars arises from convective penetration. Finally, we provide a fitting formula for the extent of core convective penetration for main-sequence stars in the mass range from 1.1-60 M ⊙.

Keywords: Stellar physics, Stellar evolutionary models, Stellar convective zones
Effects of Isoscalar- and Isovector-scalar Meson Mixing on Neutron Star Structure. Based on the accurately calibrated interaction FSUGold, we show that including isovector-scalar δ meson and its coupling to isoscalar-scalar σ meson in the relativistic mean-field (RMF) model can soften the symmetry energy E sym(n) at intermediate densities while stiffening the E sym(n) at high densities. We find this new RMF model can be simultaneously compatible with (1) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions; (2) the neutron skin thickness of 208Pb from the PREX-II experiment; (3) the largest mass of a neutron star (NS) reported so far from PSR J0740+6620; (4) the limit of Λ1.4 ≤ 580 for the dimensionless tidal deformability of the canonical 1.4 M ☉ NS from the gravitational-wave signal GW170817; (5) the mass-radius relation of PSR J0030+0451 and PSR J0740+6620 measured by NICER. The new model thus removes the tension between PREX-II and GW170817 observed in the conventional RMF model.

Keywords: Neutron stars, Nuclear astrophysics, Gravitational wave astronomy
The Nascent Milliquasar VT J154843.06+220812.6: Tidal Disruption Event or Extreme Accretion State Change?. We present a detailed multiwavelength follow-up of the nuclear radio flare VT J154843.06+220812.6, hereafter VT J1548. VT J1548 was selected as a ~1 mJy radio flare in 3 GHz observations from the Very Large Array Sky Survey. It is located in the nucleus of a low-mass ( $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }\sim 6$ ) host galaxy with weak or no past active galactic nuclei (AGN) activity. VT J1548 is associated with a slow rising (multiple year), bright mid-IR flare in the Wide-field Infrared Survey Explorer survey, peaking at ~10%L edd.. No associated optical transient is detected, although we cannot rule out a short, early optical flare given the limited data available. Constant late-time (~3 yr post-flare) X-ray emission is detected at ~1042 erg s-1. The radio spectral energy distribution is consistent with synchrotron emission from an outflow incident on an asymmetric medium. A follow-up, optical spectrum shows transient, bright, high-ionization coronal line emission ([Fe X I] λ6375, [Fe X I] λ7894, [S X I I] λ7612). Transient broad Hα is also detected but without corresponding broad Hβ emission, suggesting high nuclear extinction. We interpret this event as either a tidal disruption event or an extreme flare of an AGN, in both cases obscured by a dusty torus. Although these individual properties have been observed in previous transients, the combination is unprecedented. This event highlights the importance of searches across all wave bands for assembling a sample of nuclear flares that spans the range of observable properties and possible triggers.

Keywords: Tidal disruption, Transient sources, X-ray transient sources, Active galactic nuclei, Radio transient sources
The Dynamic Coupling of Streamers and Pseudostreamers to the Heliosphere. The slow solar wind is generally believed to result from the interaction of open and closed coronal magnetic flux at streamers and pseudostreamers. We use three-dimensional magnetohydrodynamic simulations to determine the detailed structure and dynamics of open-closed interactions that are driven by photospheric convective flows. The photospheric magnetic field model includes a global dipole giving rise to a streamer together with a large parasitic polarity region giving rise to a pseudostreamer that separates a satellite coronal hole from the main polar hole. Our numerical domain extends out to 30R ⊙ and includes an isothermal solar wind, so that the coupling between the corona and heliosphere can be calculated rigorously. This system is driven by imposing a large set of quasi-random surface flows that capture the driving of coronal flux in the vicinity of streamer and pseudostreamer boundaries by the supergranular motions. We describe the resulting structures and dynamics. Interchange reconnection dominates the evolution at both streamer and pseudostreamer boundaries, but the details of the resulting structures are clearly different from one another. Additionally, we calculate in situ signatures of the reconnection and determine the dynamic mapping from the inner heliosphere back to the Sun for a test spacecraft orbit. We discuss the implications of our results for interpreting observations from inner heliospheric missions, such as Parker Solar Probe and Solar Orbiter, and for space weather modeling of the slow solar wind.

Keywords: Slow solar wind, Magnetohydrodynamics, Solar magnetic reconnection, Solar physics, Solar corona, Solar coronal holes
The ESO-VLT MIKiS Survey Reloaded: Velocity Dispersion Profile and Rotation Curve of NGC 1904. We present an investigation of the internal kinematic properties of M79 (NGC 1904). Our study is based on radial velocity measurements obtained from the ESO-VLT Multi-Instrument Kinematic Survey (MIKiS) of Galactic globular clusters for more than 1700 individual stars distributed between ~0.″3 and 770″ (~14 three-dimensional half-mass radii) from the center. Our analysis reveals the presence of ordered line-of-sight rotation with a rotation axis almost aligned along the east-west direction and a velocity peak of 1.5 km s-1 at ~70″ from the rotation axis. The velocity dispersion profile is well described by the same King model that best fits the projected density distribution, with a constant central plateau at σ 0 ~ 6 km s-1. To investigate the cluster rotation in the plane of the sky, we have analyzed the proper motions provided by the Gaia EDR3, finding a signature of rotation with a maximum amplitude of ~2.0 km s-1 at ~80″ from the cluster center. Analyzing the three-dimensional velocity distribution for a subsample of 130 stars, we confirm the presence of systemic rotation and find a rotation axis inclination angle of 37° with respect to the line of sight. As a final result, the comparison of the observed rotation curves with the results of a representative N-body simulation of a rotating star cluster shows that the present-day kinematic properties of NGC 1904 are consistent with those of a dynamically old system that has lost a significant fraction of its initial angular momentum. *Based on observations collected at the European Southern Observatory, Cerro Paranal (Chile), under proposal 193.D-0232 (PI: Ferraro) and 0104.D-0636 (PI: Ferraro).

Keywords: Globular star clusters, Stellar kinematics, Spectroscopy
Analyzing the Habitable Zones of Circumbinary Planets Using Machine Learning. Exoplanet detection in the past decade by efforts including NASA's Kepler and TESS missions has revealed many worlds that differ substantially from planets in our own solar system, including more than 150 exoplanets orbiting binary or multi-star systems. This not only broadens our understanding of the diversity of exoplanets, but also promotes our study of exoplanets in the complex binary systems and provides motivation to explore their habitability. In this study, we investigate the habitable zones of circumbinary planets (P-type) based on planetary trajectory and dynamically informed habitable zones. Our results indicate that the mass ratio and orbital eccentricity of binary stars are important factors affecting the orbital stability and habitability of planetary systems. Moreover, planetary trajectory and dynamically informed habitable zones divide planetary habitability into three categories: habitable, periodic habitable, and non-habitable. Therefore, we successfully train a machine-learning model to quickly and efficiently classify these planetary systems, which provides more useful constraints.

Keywords: Exoplanet evolution, Habitable zone, Binary stars
Ancestral Black Holes of Binary Merger GW190521. GW190521 was the most massive black hole merger discovered by LIGO/Virgo so far, with masses in tension with stellar evolution models. A possible explanation of such heavy black holes is that they themselves are the remnants of previous mergers of lighter black holes. Here we estimate the masses of the ancestral black holes of GW190521, assuming it is the end product of previous mergers. We find that the heaviest parental black holes has a mass of ${56}_{-18}^{+20}$ M ⊙ (90% credible level). We find 70% probability that it is in the 50 M ⊙-120 M ⊙ mass gap, indicating that it may also be the end product of a previous merger. We therefore also compute the expected mass distributions of the "grandparent" black holes of GW190521, assuming they existed. Ancestral black hole masses could represent an additional puzzle piece in identifying the origin of LIGO/Virgo/KAGRA's heaviest black holes.

Keywords: Gravitational waves
Probing Planets with Exomoons: The Cases of Kepler-1708 b and Kepler-1625 b. The tidal interactions between a planet and moon can provide insight into the properties of the host planet. The recent exomoon candidates Kepler-1708 b-i and Kepler-1625 b-i are Neptune-sized satellites orbiting Jupiter-like planets and provide an opportunity to apply such methods. We show that if the tidal migration time is roughly equal to the age of these systems, then the tidal dissipation factor Q for the planets Kepler-1708 b and Kepler-1625 b have values of ~3 × 105-3 × 106 and ~1.5 × 105-4 × 105, respectively. In each case, these are consistent with estimates for gas-giant planets. Even though some work suggests an especially large semimajor axis for Kepler-1625 b-i, we find that this would imply a surprisingly low Q ~ 2000 for a gas giant unless the moon formed at essentially its current position. More detailed predictions for the moons' initial semimajor axis could provide even better constraints on Q, and we discuss the formation scenarios for a moon in this context. Similar arguments can be used as more exomoons are discovered in the future to constrain exoplanet interior properties. This could be especially useful for exoplanets near the sub-Neptune/super-Earth radius gap where the planet structure is uncertain.

Keywords: Exoplanet dynamics, Exoplanet tides, Natural satellites (Extrasolar)
Twin Extreme Ultraviolet Waves in the Solar Corona. Solar extreme ultraviolet (EUV) waves are spectacular propagating disturbances with EUV enhancements in annular shapes in the solar corona. These EUV waves carry critical information about the coronal magnetized plasma that can shed light on the elusive physical parameters (e.g., the magnetic field strength) by global solar coronal magnetoseismology. EUV waves are closely associated with a wide range of solar atmospheric eruptions, from violent flares and coronal mass ejections to less energetic plasma jets or mini-filament eruptions. However, the physical nature and driving mechanism of EUV waves are still controversial. Here, we report the unique discovery of twin EUV waves (TEWs) that were formed in a single eruption with observations from two different perspectives. In all earlier studies, a single eruption was associated at most with a single EUV wave. The newly found TEWs urge us to revisit our theoretical understanding of the underlying formation mechanism(s) of coronal EUV waves. Two distinct scenarios of TEWs were found. In the first scenario, the two waves were separately associated with a filament eruption and a precursor jet, while in another scenario, the two waves were successively associated with a filament eruption. Hence, we label these distinguished scenarios as "fraternal TEWs" and "identical TEWs," respectively. Further, we also suggest that impulsive lateral expansions of two distinct groups of coronal loops are critical to the formation of TEWs in a single eruption.

Keywords: Solar activity, Solar coronal mass ejections, Solar coronal waves, Solar corona