Sazuna/UAT_keywords huggingface dataset:
Enhanced Hydrogen Escape on Mars during the 2018 Global Dust Storm: Impact of Horizontal Wind Field. Mars has undergone a substantial water loss, transforming from the early warm and wet state to the current cold and arid state. Observations and modeling efforts suggest that hydrogen escape is a metric of water loss on Mars. As a consequence of the vertical transport of water vapor by deep convection, hydrogen escape is significantly enhanced during Martian global dust storms. Motivated by the established scenario that the horizontal wind field could substantially enhance thermal escape, here we evaluate, for the first time, how the escape of H and H2 on Mars during a typical global dust storm is modified by the enhanced horizontal wind field during the period. By combining kinetic model calculations and the Mars Climate Database outputs, we reach the conclusion that a nonnegligible enhancement of the H and H2 escape flux could be driven by horizontal winds near the exobase, reaching 15% for H and 60% for H2 at dawn near the equator during the dust storm. Although the enhancement of the global hydrogen escape rate by the horizontal wind is insignificant, it plays a crucial role in the redistribution of H and H2 escape flux. The results presented here make useful contributions to a thorough understanding of enhanced hydrogen escape during the global dust storms.

Keywords: Upper atmosphere, Solar system planets, Exosphere, Mars, Planetary atmospheres
Coagulation-Fragmentation Equilibrium for Charged Dust: Abundance of Submicron Grains Increases Dramatically in Protoplanetary Disks. Dust coagulation in protoplanetary disks is not straightforward and is subject to several slowdown mechanisms, such as bouncing, fragmentation, and radial drift to the star. Furthermore, dust grains in UV-shielded disk regions are negatively charged due to collisions with the surrounding electrons and ions, which leads to their electrostatic repulsion. For typical disk conditions, the relative velocities between micron-sized grains are small, and their collisions are strongly affected by the repulsion. On the other hand, collisions between pebble-sized grains can be too energetic, leading to grain fragmentation. The aim of the present paper is to study the combined effect of the electrostatic and fragmentation barriers on dust evolution. We numerically solve the Smoluchowski coagulation-fragmentation equation for grains whose charging occurs under conditions typical for the inner disk regions, where thermal ionization operates. We find that dust fragmentation efficiently resupplies the population of small grains under the electrostatic barrier. As a result, the equilibrium abundance of submicron grains is enhanced by several orders of magnitude compared to the case of neutral dust. For some conditions with fragmentation velocities of ~1 m s-1, macroscopic grains are completely destroyed.

Keywords: Interstellar dust, Dust physics, Young stellar objects, Protoplanetary disks, Circumstellar disks, Circumstellar dust
Propagation of a Realistic Magnetar Jet through a Binary Neutron Star Merger Medium and Implications for Short Gamma-Ray Bursts. The origin of short gamma-ray bursts is associated with outflows powered by the remnant of a binary neutron star merger. This remnant can be either a black hole or a highly magnetized, fast-spinning neutron star, also known as a magnetar. Here we present the results of two relativistic magnetohydrodynamical simulations aimed at investigating the large-scale dynamics and propagation of magnetar collimated outflows through the medium surrounding the remnant. The first simulation evolves a realistic jet by injecting external simulation data, while the second evolves an analytical model jet with similar properties for comparison. We find that both outflows remain collimated and successfully emerge through the static medium surrounding the remnant. However, they fail to attain relativistic velocities and only reach a mean maximum speed of ~0.7c for the realistic jet and ~0.6c for the analytical jet. We also find that the realistic jet has a much more complex structure. The lack of highly relativistic speeds, which makes these jets unsuitable as short gamma-ray burst sources, is due to numerical limitations and is not general to all possible magnetar outflows. A jet like the one we study, however, could give rise to or augment a blue kilonova component. In addition, it would make the propagation of a relativistic jet easier, should one be launched after the neutron star collapses into a black hole.

Keywords: Neutron stars, Gamma-ray bursts, Relativistic jets, Magnetohydrodynamical simulations
Coronal Loops with Different Metallicities and Generalized RTV Scaling Laws. Stellar metallicity is a critical factor to characterize the stellar coronae because it directly affects the radiative energy loss from the atmosphere. By extending theoretical relations for solar coronal loops introduced by Rosner et al., we analytically derive scaling relations for stellar coronal loops with various metallicities. In order to validate the derived relations, we also perform magnetohydrodynamic simulations for the heating of coronal loops with different metallicities by changing radiative-loss functions according to the adopted elemental abundances. The simulation results nicely explain the generalized analytical scaling relations and show a strong dependence of the thermodynamical and radiative properties of the loops on metallicity. Higher density and temperature are obtained in lower-metallicity coronae because of the inefficient radiative cooling, provided that the surface condition is unchanged. Thus, it is estimated that the X-ray radiation from metal-poor coronae is higher because of their denser coronal gas. The generalized scaling laws can also be used as a tool to study the condition of high-energy radiation around magnetically active stars and their impact on planetary environments.

Keywords: Stellar coronae, Metallicity, Stellar atmospheres, Magnetohydrodynamical simulations
Characterizing CO Emitters in the SSA22-AzTEC26 Field. We report the physical characterization of four CO emitters detected near the bright submillimeter galaxy (SMG) SSA22-AzTEC26. We analyze the data from Atacama Large Millimeter/submillimeter Array band 3, 4, and 7 observations of the SSA22-AzTEC26 field. In addition to the targeted SMG, we detect four line emitters with signal-to-noise ratio &gt;5.2 in the cube smoothed with a 300 km s-1 FWHM Gaussian filter. All four sources have NIR counterparts within 1″. We perform UV-to-FIR spectral energy distribution modeling to derive the photometric redshifts and physical properties. Based on the photometric redshifts, we reveal that two of them are CO(2-1) at redshifts of 1.113 and 1.146 and one is CO(3-2) at z = 2.124. The three sources are massive galaxies with a stellar mass ≳1010.5 M ⊙, but have different levels of star formation. Two lie within the scatter of the main sequence (MS) of star-forming galaxies at z ~ 1-2, and the most massive galaxy lies significantly below the MS. However, all three sources have a gas fraction within the scatter of the MS scaling relation. This shows that a blind CO line search can detect massive galaxies with low specific star formation rates that still host large gas reservoirs and that it also complements targeted surveys, suggesting later gas acquisition and the need for other mechanisms in addition to gas consumption to suppress star formation.

Keywords: Molecular gas, High-redshift galaxies, Galaxy evolution, CO line emission
ALMA ACA Detection of Submillimeter Emission Associated with the Western Hot Spot of the Radio Galaxy Pictor A. In order to investigate the far-infrared excess detected from the western hot spot of the radio galaxy Pictor A with the Herschel observatory, submillimeter photometry is performed with the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array at Band 8 with the reference frequency of 405 GHz. A submillimeter source is discovered at the radio peak of the hot spot. Because the 405 GHz flux density of the source, 80.7 ± 3.1 mJy, agrees with the extrapolation of the synchrotron radio spectrum, the far-infrared excess is suggested to exhibit no major contribution at the ACA band. In contrast, by subtracting the power-law spectrum tightly constrained by the radio and ACA data, the significance of the excess in the Herschel band is well confirmed. No diffuse submillimeter emission is detected within the ACA field of view, and thus, the excess is ascribed to the western hot spot itself. In comparison to the previous estimate based on the Herschel data, the relative contribution of the far-infrared excess is reduced by a factor of ~1.5. The spectrum of the excess below the far-infrared band is determined to be harder than that of the diffusive shock acceleration. This strengthens the previous interpretation that the excess originates via the magnetic turbulence in the substructures within the hot spot. The ACA data are utilized to evaluate the magnetic field strength of the excess and of diffuse radio structure associated with the hot spot.

Keywords: Relativistic jets, Non-thermal radiation sources, Fanaroff-Riley radio galaxies, Radio interferometers, Radio hot spots, Magnetic fields
Observations and Chemical Modeling of the Isotopologues of Formaldehyde and the Cations of Formyl and Protonated Formaldehyde in the Hot Molecular Core G331.512-0.103. In the interstellar cold gas, the chemistry of formaldehyde (H2CO) can be essential to explain the formation of complex organic molecules. On this matter, the massive and energetic protostellar object G331 is still unexplored; hence, we carried out a comprehensive study of the isotopologues of H2CO, the formyl cation (HCO+), and protonated formaldehyde (H2COH+) through the APEX observations in a spectral window of ~159-356 GHz. We employed observational and theoretical methods to derive the physical properties of the molecular gas combining LTE and non-LTE analyses. Formaldehyde was characterized via 35 lines of H2CO, ${{\rm{H}}}_{2}^{13}$ CO, HDCO, and H2C18O. The formyl cation was detected via eight lines of HCO+, H13CO+, HC18O+, and HC17O+. Deuterium was clearly detected via HDCO, whereas DCO+ remained undetected. The H2COH+ was detected through three clean lines. According to the radiative analysis, formaldehyde appears to be embedded in a bulk gas with a wide range of temperatures (T ~ 20-90 K), while HCO+ and H2COH+ are primarily associated with colder gas (T ≲ 30 K). The reaction H2CO+HCO+ → H2COH+ + CO is crucial for the balance of the three species. We used the Nautilus gas-grain code to predict the evolution of their molecular abundances relative to H2; their values at timescales of ~103 yr matched the observations in G331: [H2CO] = (0.2-2) × 10-8, [HCO+] = (0.5-4) × 10-9, and [H2COH+] = (0.2-2) × 10-10. Based on the molecular evolution of H2CO, HCO+, and H2COH+, we hypothesized about the young lifetime of G331, which is consistent with the active gas-grain chemistry of massive protostellar objects.

Keywords: Interstellar molecules, Molecular data, Spectral line identification, Star forming regions, Astronomy data analysis, Astrochemistry, Molecular reactions
A Multiwavelength Light-curve Analysis of the Classical Nova YZ Ret: An Extension of the Universal Decline Law to the Nebular Phase. YZ Ret is the first X-ray flash detected classical nova, and is also observed in optical, X-ray, and gamma-ray. We propose a comprehensive model that explains the observational properties. The white dwarf mass is determined to be ~1.33 M ☉, which reproduces the multiwavelength light curves of YZ Ret, from optical, X-ray, to gamma-ray. We show that a shock is naturally generated far outside the photosphere because winds collide with themselves. The derived lifetime of the shock explains some of the temporal variations of emission lines. The shocked shell significantly contributes to the optical flux in the nebular phase. The decline trend of shell emission in the nebular phase is close to ∝t -1.75 and the same as the universal decline law of classical novae, where t is the time from the outburst.

Keywords: X-ray astronomy, High energy astrophysics, Fast novae, Shocks, Gamma-ray astronomy, Classical novae, VY Sculptoris stars
Translational Tomography with the Wide-field Imager for Parker Solar Probe (WISPR). I. Theoretical Basis and Initial Modeling. In the first of a planned sequence of articles, we present a simple method for reconstructing radial density structures of the solar corona in the vicinity of the Parker Solar Probe (PSP) near and during perihelion passes. We describe how we model the apparent kinematics of stationary K-corona striae from the PSP Wide-field Imager for Parker Solar Probe (WISPR) viewpoint using a simple two-parameter model, form a partial basis of the data space that is a WISPR image sequence, and change the basis from image coordinates to "tomographic coordinates" in order to determine the parameters of such features. We apply the method to a simple three-dimensional model of a WISPR coronal flythrough, demonstrate the ways that it succeeds and fails, and discuss possible improvements to the sensitivity and applicability of the method for real WISPR data.

Keywords: Solar wind, Solar corona
Symmetry Breaking in Merging Binary Black Holes from Young Massive Clusters and Isolated Binaries. Properties of the to-date observed binary black hole (BBH) merger events suggest a preference toward spin-orbit aligned mergers. Naturally, this has caused widespread interest and speculations regarding implications on various merger formation channels. Here we show that (i) not only the BBH merger population from isolated binaries but also (ii) BBH population formed in young massive clusters (YMCs) would possess an asymmetry in favor of aligned mergers, in the distribution of the events' effective spin parameter (χ eff). In our analysis, we utilize BBH merger outcomes from state-of-the-art N-body evolutionary models of YMCs and isolated binary population synthesis. We incorporate, for the first time in such an analysis, misalignments due to both natal kicks and dynamical encounters. The YMC χ eff distribution has a mean (an antialigned merger fraction) of &lt;χ eff&gt; ≤ 0.04 (f  X  - ≈ 40%), which is smaller (larger) than but consistent with the observed asymmetry of &lt;χ eff&gt; ≈ 0.06 (f  X  - ≈ 28%) as obtained from the population analysis by the LIGO-Virgo-KAGRA collaboration. In contrast, isolated binaries alone tend to produce a much stronger asymmetry; for the tested physical models, &lt;χ eff&gt; ≈ 0.25 and f  X  - ≲ 7%. Although the YMC χ eff distribution is more similar to the observed counterpart, none of the channels correctly reproduce the observed distribution. Our results suggest that further extensive model explorations for both isolated binary and dynamical channels as well as better observational constraints are necessary to understand the physics of "the symmetry breaking" of the BBH merger population.

Keywords: Close binary stars, Massive stars, Young massive clusters, Stellar mass black holes, Gravitational wave sources, N-body simulations
Triple Spiral Arms of a Triple Protostar System Imaged in Molecular Lines. Most stars form in multiple-star systems. For a better understanding of their formation processes, it is important to resolve the individual protostellar components and the surrounding envelope and disk material at the earliest possible formation epoch, because the formation history can be lost in a few orbital timescales. Here we present Atacama Large Millimeter/submillimeter Array observational results of a young multiple protostellar system, IRAS 04239+2436, where three well-developed large spiral arms were detected in the shocked SO emission. Along the most conspicuous arm, the accretion streamer was also detected in the SO2 emission. The observational results are complemented by numerical magnetohydrodynamic simulations, where those large arms only appear in magnetically weakened clouds. Numerical simulations also suggest that the large triple spiral arms are the result of gravitational interactions between compact triple protostars and the turbulent infalling envelope.

Keywords: Star formation
PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST. A full understanding of how unusually large ultradiffuse galaxies (UDGs) fit into our conventional theory of galaxy formation remains elusive, despite the large number of objects identified locally. A natural extension of UDG research is the study of similar galaxies at higher redshift to establish how their properties may evolve over time. However, this has been a challenging task given how severely systematic effects and cosmological surface brightness dimming inhibit our ability to analyze low surface brightness galaxies at high z. Here, we present a sample of low stellar surface density galaxies (LDGs) at moderate redshift, likely the progenitors of local UDGs, identified using deep near-IR observations of the El Gordo cluster at z = 0.87 with JWST. By stacking eight NIRCAM filters, we reach an apparent surface brightness sensitivity of 24.59 mag arcsec-2, which is faint enough to be complete to the bright end of the LDG population. Our analysis identifies significant differences between this population and UDGs observed locally, such as their color and size distributions, which suggest that the UDG progenitors at high z are bluer and more extended than UDGs at z = 0. This suggests that multiple mechanisms are responsible for the UDG formation and that prolonged transformation of cluster dwarfs is not a primary UDG formation mechanism at high z. Furthermore, we find a slight overabundance of LDGs in El Gordo, and, in contrast to findings in local clusters, our analysis does not show a deficit of LDGs in the center of El Gordo, implying that tidal destruction of LDGs is significant between z = 0.87 and z = 0.

Keywords: Galaxy clusters, Stellar populations, Galaxy structure, James Webb Space Telescope, Galaxy evolution, Low surface brightness galaxies
Reconnection-generated Plasma Flows in the Quasi-separatrix Layer in Localized Solar Corona. Multiwavelength observations of the propagating disturbances (PDs), discovered by Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO), are analyzed to determine their driving mechanism and physical nature. Two magnetic strands in the localized corona are observed to approach and merge with each other, followed by the generation of brightening, which further propagates in a cusp-shaped magnetic channel. Differential emission measure analysis shows an occurrence of heating in this region of interest. We extrapolate potential magnetic field lines at coronal heights from the observed Helioseismic and Magnetic Imager vector magnetogram via Green's function method using MPI-AMRVAC. We analyze the field to locate magnetic nulls and quasi-separatrix layers (QSLs), which are preferential locations for magnetic reconnection. Dominant QSLs including a magnetic null are found to exist and match the geometry followed by PDs; therefore, this provides conclusive evidence of magnetic reconnection. In addition, spectroscopic analysis of Interface Region Imaging Spectrograph Si IV λ1393.77 line profiles show a rise of line width in the same time range depicting the presence of mass motion in the observed cusp-shaped region. PDs are observed to exhibit periodicities of around 4 minutes. The speeds of PDs measured by the surfing transform technique are close to each other in four different SDO/AIA bandpasses, i.e., 304, 171, 193, and 131 Å, excluding the interpretation of PDs in terms of slow magnetoacoustic waves. We describe comprehensively the observed PDs as quasiperiodic plasma flows generated as a result of periodic reconnection in the vicinity of a coronal magnetic null.

Keywords: Solar coronal transients, Solar corona, Solar magnetic reconnection
Heliocentric Distance and Solar Activity Dependence of Sustained Quasi-radial Interplanetary Magnetic Field Occurrence. Planets close to their stars experience an interplanetary magnetic field (IMF) that is dominantly quasi-radial. Our solar system serves as a laboratory to study how the occurrence of quasi-radial IMF varies away from the star and under different stellar activities. Furthermore, on time and spatial scales relevant to magnetospheric physics, solar wind variability prevails in the form of structures generated both at the Sun and locally in the interplanetary space. The stationary Parker spiral model only approximates the large-scale structure of the IMF. Deviations from the Parker spiral often result in strongly radial magnetic fields that give rise to kinetic foreshock turbulence, which in turn can impact planetary magnetospheres. The relative significance of this type of interaction can be estimated statistically based on the occurrence rate of cases where the IMF is directed along the radial direction, leading to the entire day-side magnetosphere being downstream of the ion foreshock. We use observations covering radial distances from 0.1 to 10 au and more than 2 solar cycles to quantify the prevalence of radial IMFs throughout the heliosphere. Near Earth's orbit, it is found that the occurrence rates of quasi-radial and southward IMF orientations are similar, and that the Pearson correlation coefficient is ${{ \mathcal R }}_{{xy}}\sim -0.7$ calculated between quasi-radial IMF occurrence rate and solar activity. A negative correlation is demonstrated for radial distances extending to at least Mars but not to Saturn.

Keywords: Planetary bow shocks, Interplanetary magnetic fields, Solar cycle
Modeling the Multiwavelength Evolution of the V960 Mon System. We study the evolution of the FU Ori object V960 Mon since its outburst, using available multiwavelength photometric time series over 8 yr, complemented by several epochs of moderate-dispersion spectrophotometry. We find that the source fading can be well-described by a decrease in the temperature of the inner disk, which results from a combination of decreasing accretion rate and increasing inner disk radius. We model the system with a disk atmosphere model that produces the observed variations in multiband photometry (this paper) and high-resolution spectral lines (a companion paper).

Keywords: Optical bursts, FU Orionis stars, Young stellar objects, Infrared sources, Stellar accretion disks
No Small-scale Radio Jets Here: Multiepoch Observations of Radio Continuum Structures in NGC 1068 with the VLBA. We present recent Very Long Baseline Array (VLBA) 5 GHz radio observations of the nearby, luminous Seyfert 2 galaxy NGC 1068 for comparison to similar VLBA observations made on 1997 April 26. By cross-correlating the positions of emitting regions across both epochs, we find that spatially resolved extranuclear radio knots in this system have subrelativistic transverse speeds (v ≲0.1c). We discuss sources of the observed knots and how the radio emission relates to additional phases of gas in the central ~150 pc of this system. We suggest that the most likely explanation for the observed emission is synchrotron radiation formed by shocked host media via interactions between active galactic nucleus winds and the host environment.

Keywords: AGN host galaxies, Radio astronomy, Active galactic nuclei