adsabs/SciX_UAT_keywords huggingface dataset:
The Impact of Effective Matter Mixing Based on Three-dimensional Hydrodynamical Models on the Molecule Formation in the Ejecta of SN 1987A

To investigate the impact of matter mixing on the formation of molecules in the ejecta of SN 1987A, time-dependent rate equations for chemical reactions are solved for one-zone and one-dimensional (1D) ejecta models of SN 1987A. The latter models are based on the 1D profiles obtained by angle-averaging of the three-dimensional (3D) hydrodynamical models, which effectively reflect the 3D matter mixing; the impact is demonstrated, for the first time, based on 3D hydrodynamical models. The distributions of initial seed atoms and radioactive 56Ni influenced by the mixing could affect the formation of molecules. By comparing the calculations for spherical cases and for several specified directions in the bipolar-like explosions in the 3D hydrodynamical models, the impact is discussed. The decay of 56Ni, practically 56Co at later phases, could heat the gas and delay the molecule formation. Additionally, Compton electrons produced by the decay could ionize atoms and molecules and could destroy molecules. Several chemical reactions involved with ions such as H+ and He+ could also destroy molecules. The mixing of 56Ni plays a nonnegligible role in both the formation and destruction of molecules through the processes above. The destructive processes of carbon monoxide and silicon monoxide due to the decay of 56Ni generally reduce the amounts. However, if the molecule formation is sufficiently delayed under a certain condition, the decay of 56Ni could locally increase the amounts through a sequence of reactions.

Keywords: core-collapse supernovae; supernova remnants; astrochemistry
Extracting the Main Trend in a Data Set: The Sequencer Algorithm

Scientists aim to extract simplicity from observations of the complex world. An important component of this process is the exploration of data in search of trends. In practice, however, this tends to be more of an art than a science. Among all trends existing in the natural world, one-dimensional trends, often called sequences, are of particular interest, as they provide insights into simple phenomena. However, some are challenging to detect, as they may be expressed in complex manners. We present the Sequencer, an algorithm designed to generically identify the main trend in a data set. It does so by constructing graphs describing the similarities between pairs of observations, computed with a set of metrics and scales. Using the fact that continuous trends lead to more elongated graphs, the algorithm can identify which aspects of the data are relevant in establishing a global sequence. Such an approach can be used beyond the proposed algorithm and can optimize the parameters of any dimensionality reduction technique. We demonstrate the power of the Sequencer using real-world data from astronomy, geology, and images from the natural world. We show that, in a number of cases, it outperforms the popular t-Distributed Stochastic Neighbor Embedding and Uniform Manifold Approximation and Projection dimensionality reduction techniques. This approach to exploratory data analysis, which does not rely on training or tuning any parameter, has the potential to enable discoveries in a wide range of scientific domains. The source code is available on GitHub, and we provide an online interface at http://sequencer.org.

Keywords: astronomy data analysis
A Very Young Radio-loud Magnetar

The magnetar Swift J1818.0-1607 was discovered in 2020 March when Swift detected a 9 ms hard X-ray burst and a long-lived outburst. Prompt X-ray observations revealed a spin period of 1.36 s, soon confirmed by the discovery of radio pulsations. We report here on the analysis of the Swift burst and follow-up X-ray and radio observations. The burst average luminosity was Lburst ∼ 2 × 1039 erg s-1 (at 4.8 kpc). Simultaneous observations with XMM-Newton and NuSTAR three days after the burst provided a source spectrum well fit by an absorbed blackbody ( ${N}_{{\rm{H}}}$ = (1.13 ± 0.03) × 1023 cm-2 and kT = 1.16 ± 0.03 keV) plus a power law (Γ = 0.0 ± 1.3) in the 1-20 keV band, with a luminosity of ∼8 × 1034 erg s-1, dominated by the blackbody emission. From our timing analysis, we derive a dipolar magnetic field B ∼ 7 × 1014 G, spin-down luminosity ${\dot{E}}_{\mathrm{rot}}\sim 1.4\times {10}^{36}$ erg s-1, and characteristic age of 240 yr, the shortest currently known. Archival observations led to an upper limit on the quiescent luminosity <5.5 × 1033 erg s-1, lower than the value expected from magnetar cooling models at the source characteristic age. A 1 hr radio observation with the Sardinia Radio Telescope taken about 1 week after the X-ray burst detected a number of strong and short radio pulses at 1.5 GHz, in addition to regular pulsed emission; they were emitted at an average rate 0.9 min-1 and accounted for ∼50% of the total pulsed radio fluence. We conclude that Swift J1818.0-1607 is a peculiar magnetar belonging to the small, diverse group of young neutron stars with properties straddling those of rotationally and magnetically powered pulsars. Future observations will make a better estimation of the age possible by measuring the spin-down rate in quiescence.

Keywords: magnetars; neutron stars; transient sources; x-ray bursts; radio pulsars
High-resolution Observations of Small-scale Flux Emergence by GST

Recent observations demonstrated that emerging flux regions, which constitute the early stage of solar active regions, consist of emergence of numerous small-scale magnetic elements. They in turn interact, merge, and form mature sunspots. However, observations of fine magnetic structures on photosphere with subarcsecond resolution are very rare due to limitations of observing facilities. In this work, taking advantage of the high resolution of the 1.6 m Goode Solar Telescope, we jointly analyze vector magnetic fields, continuum images, and Hα observations of NOAA AR 12665 on 2017 July 13, with the goal of understanding the signatures of small-scale flux emergence, as well as their atmospheric responses as they emerge through multiple heights in the photosphere and chromosphere. Under such a high resolution of 0"1-0"2, our results confirm two kinds of small-scale flux emergence: magnetic flux sheet emergence associated with the newly forming granules, and the traditional magnetic flux loop emergence. With direct imaging in the broadband TiO, we observe that both types of flux emergence are associated with darkening of granular boundaries, while only flux sheets elongate granules along the direction of emerging magnetic fields and expand laterally. With a life span of 10 ∼ 15 minutes, the total emerged vertical flux is on the order of 1018 Mx for both types of emergence. The magnitudes of the vertical and horizontal fields are comparable in the flux sheets, while the former is stronger in flux loops. Hα observations reveal transient brightenings in the wings in the events of magnetic loop emergence, which are most probably the signatures of Ellerman bombs.

Keywords: solar magnetic flux emergence; solar photosphere; solar magnetic fields; solar activity
Effects of Different Closure Choices in Core-collapse Supernova Simulations

The two-moment method is widely used to approximate the full neutrino transport equation in core-collapse supernova (CCSN) simulations, and different closures lead to subtle differences in the simulation results. In this paper, we compare the effects of closure choices on various physical quantities in 1D and 2D time-dependent CCSN simulations with our multigroup radiation hydrodynamics code FORNAX. We find that choices of the third-order closure relations influence the time-dependent simulations only slightly. Choices of the second-order closure relation have larger consequences than choices of the third-order closure, but these are still small compared to the remaining variations due to ambiguities in some physical inputs such as the nuclear equation of state. We also find that deviations in Eddington factors are not monotonically related to deviations in physical quantities, which means that simply comparing the Eddington factors does not inform one concerning which closure is better.

Keywords: core-collapse supernovae; radiative transfer; supernova neutrinos
Molecular Cloud Populations in the Context of Their Host Galaxy Environments: A Multiwavelength Perspective

We present a rich, multiwavelength, multiscale database built around the PHANGS-ALMA CO (2 - 1) survey and ancillary data. We use this database to present the distributions of molecular cloud populations and subgalactic environments in 80 PHANGS galaxies, to characterize the relationship between population-averaged cloud properties and host galaxy properties, and to assess key timescales relevant to molecular cloud evolution and star formation. We show that PHANGS probes a wide range of kpc-scale gas, stellar, and star formation rate (SFR) surface densities, as well as orbital velocities and shear. The population-averaged cloud properties in each aperture correlate strongly with both local environmental properties and host galaxy global properties. Leveraging a variable selection analysis, we find that the kpc-scale surface densities of molecular gas and SFR tend to possess the most predictive power for the population-averaged cloud properties. Once their variations are controlled for, galaxy global properties contain little additional information, which implies that the apparent galaxy-to-galaxy variations in cloud populations are likely mediated by kpc-scale environmental conditions. We further estimate a suite of important timescales from our multiwavelength measurements. The cloud-scale freefall time and turbulence crossing time are ~5-20 Myr, comparable to previous cloud lifetime estimates. The timescales for orbital motion, shearing, and cloud-cloud collisions are longer, ~100 Myr. The molecular gas depletion time is 1-3 Gyr and shows weak to no correlations with the other timescales in our data. We publish our measurements online, and expect them to have broad utility to future studies of molecular clouds and star formation.

Keywords: molecular clouds; star formation; disk galaxies; millimeter astronomy
Enhanced X-Ray Emission from the Most Radio-powerful Quasar in the Universe's First Billion Years

We present deep (265 ks) Chandra X-ray observations of PSO J352.4034-15.3373, a quasar at z = 5.831 that, with a radio-to-optical flux ratio of R > 1000, is one of the radio-loudest quasars in the early universe and is the only quasar with observed extended radio jets of kiloparsec scale at z ≳ 6. Modeling the X-ray spectrum of the quasar with a power law, we find a best fit of ${\rm{\Gamma }}={1.99}_{-0.28}^{+0.29}$ , leading to an X-ray luminosity of ${L}_{2\mbox{--}10}={1.26}_{-0.33}^{+0.45}\times {10}^{45}\ \mathrm{erg}\ {{\rm{s}}}^{-1}$ and an X-ray to UV brightness ratio of αOX = -1.45 ± -0.11. We identify a diffuse structure 50 kpc (∼8″) to the NW of the quasar along the jet axis that corresponds to a 3σ enhancement in the angular density of emission and can be ruled out as a background fluctuation with a probability of P = 0.9985. While with few detected photons the spectral fit of the structure is uncertain, we find that it has a luminosity of L2-10 ∼ 1044 erg s-1. These observations therefore potentially represent the most distant quasar jet yet seen in X-rays. We find no evidence for excess X-ray emission where the previously reported radio jets are seen (which have an overall linear extent of 0"28), and a bright X-ray point source located along the jet axis to the SE is revealed by optical and NIR imaging to not be associated with the quasar.

Keywords: x-ray quasars; x-ray astronomy; radio loud quasars; quasars; jets
GJ 3929: High-precision Photometric and Doppler Characterization of an Exo-Venus and Its Hot, Mini-Neptune-mass Companion

We detail the follow-up and characterization of a transiting exo-Venus identified by TESS, GJ 3929b (TOI-2013b), and its nontransiting companion planet, GJ 3929c (TOI-2013c). GJ 3929b is an Earth-sized exoplanet in its star's Venus zone (P b = 2.616272 ± 0.000005 days; S b = ${17.3}_{-0.7}^{+0.8}$ S ⊕) orbiting a nearby M dwarf. GJ 3929c is most likely a nontransiting sub-Neptune. Using the new, ultraprecise NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak National Observatory, we are able to modify the mass constraints of planet b reported in previous works and consequently improve the significance of the mass measurement to almost 4σ confidence (M b = 1.75 ± 0.45 M ⊕). We further adjust the orbital period of planet c from its alias at 14.30 ± 0.03 days to the likely true period of 15.04 ± 0.03 days, and we adjust its minimum mass to $m\sin i$ = 5.71 ± 0.92 M ⊕. Using the diffuser-assisted ARCTIC imager on the ARC 3.5 m telescope at Apache Point Observatory, in addition to publicly available TESS and LCOGT photometry, we are able to constrain the radius of planet b to R p = 1.09 ± 0.04 R ⊕. GJ 3929b is a top candidate for transmission spectroscopy in its size regime (TSM = 14 ± 4), and future atmospheric studies of GJ 3929b stand to shed light on the nature of small planets orbiting M dwarfs.

Keywords: exoplanets; mini neptunes; super earths; transmission spectroscopy; radial velocity; transits
Radiative-dynamical Model of Jupiter's Quasi-quadrennial Oscillation

We present a simulation of Jupiter's quasi-quadrennial oscillation (QQO) in a 2D radiative-dynamical model. Launching an eastward Kelvin wave and a westward Rossby-gravity wave in the lower boundary, we successfully generate a 4 yr-period oscillation in the equatorial stratosphere. The momentum flux of waves initiates overlying easterly–westerly wind jets descending in altitude with the maximum temperature variation of ±5 K near 10 hPa at the equator. The tropical stratospheric region is dominated by upwelling and downwelling circulation cells induced by the QQO, affecting the midlatitude where stratospheric aerosols enrich. The simulation results are consistent with the previous satellite and ground-based observations in the low latitudes and provide the ability to examine the QQO's influence in Jupiter's extratropical stratosphere. The QQO influence further extends into the upper troposphere, forming a weak anticorrelation with the stratosphere oscillation in agreement with the result from 40 yr of telescope observations.

Keywords: jupiter; atmospheric circulation; planetary atmospheres; planetary science; planetary dynamics; solar system gas giant planets
Validation and Testing of the CROBAR 3D Coronal Reconstruction Method with a MURaM Simulation

I report on validation and testing of a novel 3D reconstruction method than can obtain coronal plasma properties from a single snapshot perspective. I first reported on the method in 2021, and I have since named it the Coronal Reconstruction Onto B-Aligned Regions (CROBAR) method. The testing and validation are carried out with a cube from a MURaM 3D MHD simulation, which affords a coronal-like "ground truth" against which the reconstruction method can be applied and compared. I find that the method does quite well, recovering the "coronal veil"-like features recently reported from the MURaM simulations and allaying concerns that these features would thwart recovery of valid 3D coronal structure from a limited number of perspectives. I also find that a second perspective between ~45° and 90° does significantly improve the reconstructions. Two distinct channels with soft-X-ray-like temperature response (peaking above 5 MK) would suffice for CROBAR's optically thin observables A suite of AIA-like EUV passbads, with good coverage in the 3-8 MK range, is also well suited to CROBAR.

Keywords: active solar corona; solar corona; solar coronal loops; astronomy data analysis; solar magnetic fields; astronomy data modeling; computational methods; solar extreme ultraviolet emission; solar x-ray emission
Polarization from Aligned Dust Grains in the β Pic Debris Disk

We present 870 μm Atacama Large Millimeter/submillimeter Array polarization observations of thermal dust emission from the iconic, edge-on debris disk β Pic. While the spatially resolved map does not exhibit detectable polarized dust emission, we detect polarization at the ~3σ level when averaging the emission across the entire disk. The corresponding polarization fraction is P frac = 0.51% ± 0.19%. The polarization position angle χ is aligned with the minor axis of the disk, as expected from models of dust grains aligned via radiative alignment torques (RAT) with respect to a toroidal magnetic field (B-RAT) or with respect to the anisotropy in the radiation field (k-RAT). When averaging the polarized emission across the outer versus inner thirds of the disk, we find that the polarization arises primarily from the SW third. We perform synthetic observations assuming grain alignment via both k-RAT and B-RAT. Both models produce polarization fractions close to our observed value when the emission is averaged across the entire disk. When we average the models in the inner versus outer thirds of the disk, we find that k-RAT is the likely mechanism producing the polarized emission in β Pic. A comparison of timescales relevant to grain alignment also yields the same conclusion. For dust grains with realistic aspect ratios (i.e., s > 1.1), our models imply low grain-alignment efficiencies.

Keywords: a stars; debris disks; dust continuum emission; interferometry; interplanetary dust; interplanetary magnetic fields; polarimetry; submillimeter astronomy; radiative transfer simulations; theoretical models
Determining the Composition of Relativistic Jets from Polarization Maps

We present a stationary, axisymmetric, self-similar, semianalytic model of magnetically dominated jet plasma based on force-free regions of a relativistic magnetohydrodynamic simulation. We use this model to illustrate how the composition of relativistic jet plasma can be determined, with special attention to the example of M87. In particular, we compute synthetic Stokes maps in e-e+p plasmas with various positron-to-proton ratios using synchrotron emission models to scale the partial pressure of electrons and positrons that emit at the observed frequency to the magnetic pressure, taking into account Faraday rotation and conversion. The lepton-dominated models produce bilaterally asymmetric radio intensity profiles with strong linear polarization and Stokes Q and U maps that are bilaterally asymmetric (but strongly correlated across the jet axis) and antisymmetric (and sometimes anticorrelated), respectively. The hadronic models produce more centrally brightened intensity and polarization maps. Circular polarization provides the cleanest observational tool for distinguishing the plasmas, as it increases outward from the jet core and central axis for highly ionic plasma, and is suppressed for pair-dominated plasma. We find a measurable degree of circular polarization V/I of ${ \mathcal O }({10}^{-2})$ for subequipartition hadronic jet plasmas averaged over milliarcsecond scales. Our stationary model predicts that the intensity-normalized autocorrelation functions of Q and U increase and decrease with frequency, respectively, for higher plasma betas in our parameter survey. On the other hand, the autocorrelation of V is sensitive to the frequency at lower betas. Multiband polarimetric observations could therefore be used as a novel probe of the composition of jet plasma.

Keywords: relativistic jets; magnetohydrodynamical simulations; magnetic fields; supermassive black holes; quasars; bl lacertae objects
A Python Project Template for Healthy Scientific Software

The creation of "healthy" scientific software is vital for its successful long-term adoption in scientific research. Here healthy code is defined to mean software that is usable, maintainable, and proffers consistently reproducible results. Incorporating tooling and practices to achieve these goals often leads to short-term, yet significant, overhead for new projects. We introduce the LINCC Frameworks Python Project Template, a configurable code template designed for scientific software projects that greatly simplifies adopting best practices by automating the setup and configuration of important tools locally and via a suite of GitHub workflows. Notably, the template does not include any application-specific code, thereby enabling users to focus on their scientific code rather than building or maintaining code infrastructure.

Keywords: open source software
Estimating the Energy Dissipation from Kelvin-Helmholtz Instability Induced Turbulence in Oscillating Coronal Loops

Kelvin-Helmholtz instability induced turbulence is one promising mechanism by which loops in the solar corona can be heated by MHD waves. In this Letter we present an analytical model of the dissipation rate of Kelvin-Helmholtz instability induced turbulence ɛD, finding it scales as the wave amplitude (d) to the third power (ɛD ∝ d3). Based on the concept of steady-state turbulence, we expect the turbulence heating throughout the volume of the loop to match the total energy injected through its footpoints. In situations where this holds, the wave amplitude has to vary as the cube-root of the injected energy. Comparing the analytic results with those of simulations shows that our analytic formulation captures the key aspects of the turbulent dissipation from the numerical work. Applying this model to the observed characteristics of decayless kink waves we predict that the amplitudes of these observed waves are insufficient to turbulently heat the solar corona.

Keywords: solar coronal heating; solar corona; solar coronal waves; magnetohydrodynamics
HAT-P-58b-HAT-P-64b: Seven Planets Transiting Bright Stars

We report the discovery and characterization of seven transiting exoplanets from the HATNet survey. The planets, which are hot Jupiters and Saturns transiting bright Sun-like stars, include: HAT-P-58b (with mass Mp = 0.37 MJ, radius Rp = 1.33 RJ, and orbital period P = 4.0138 days), HAT-P-59b (Mp = 1.54 MJ, Rp = 1.12 RJ, P = 4.1420 days), HAT-P-60b (Mp = 0.57 MJ, Rp = 1.63 RJ, P = 4.7948 days), HAT-P-61b (Mp = 1.06 MJ, Rp = 0.90 RJ, P = 1.9023 days), HAT-P-62b (Mp = 0.76 MJ, Rp = 1.07 RJ, P = 2.6453 days), HAT-P-63b (Mp = 0.61 MJ, Rp = 1.12 RJ, P = 3.3777 days), and HAT-P-64b (Mp = 0.58 MJ, Rp = 1.70 RJ, P = 4.0072 days). The typical errors on these quantities are 0.06 MJ, 0.03 RJ, and 0.2 s, respectively. We also provide accurate stellar parameters for each of the host stars. With V = 9.710 ± 0.050 mag, HAT-P-60 is an especially bright transiting planet host, and an excellent target for additional follow-up observations. With Rp = 1.703 ± 0.070 RJ, HAT-P-64b is a highly inflated hot Jupiter around a star nearing the end of its main-sequence lifetime, and is among the largest known planets. Five of the seven systems have long-cadence observations by TESS which are included in the analysis. Of particular note is HAT-P-59 (TOI-1826.01) which is within the northern continuous viewing zone of the TESS mission, and HAT-P-60, which is the TESS candidate TOI-1580.01. * Based on observations of the Hungarian-made Automated Telescope Network and observations obtained at the following observatories: W. M. Keck Observatory, the 1.5 m and the 1.2 m telescopes at the Fred Lawrence Whipple Observatory of the Smithsonian Astrophysical Observatory, the Kitt Peak National Observatory, the 1.93 m telescope at Observatoire de Haute-Provence, the Subaru Telescope of the National Astronomical Observatory of Japan, the Nordic Optical Telescope in the Spanish Observatorio del Roque de los Muchachos of the Intituto de Astrofísica de Canarias, and the Apache Point Observatory 3.5 m telescope.

Keywords: exoplanets; hot jupiters; exoplanet astronomy; astronomical instrumentation