Sazuna/UAT_keywords huggingface dataset:
Physical and Chemical Properties of the Molecular Gas Associated with the Mid-infrared Bubble S156. Using archival infrared data of GLIMPSE, Hi-GAL, and molecular line data of SEDIGISM, MSGPCOS, and MALT90, we investigate the physical and chemical properties of the molecular gas associated with the mid-infrared bubble S156. By the method of spectral energy distribution, we made H2 column density and dust temperature maps of this region. We find two clouds with masses of 5.4 ± 1.1 × 104 M ☉ and 2.2 ± 0.5 × 104 M ☉, respectively. In both of the two clouds, the 13CO (2-1/1-0) and 13CO (2-1)/N2H+ (1-0) intensity ratios are enhanced on the boundary. Cloud A has a clear dust temperature gradient decreasing from the boundary to the outside region. Our analysis indicates cloud A is mainly influenced by the feedback from S156, while cloud B is affected both by S156 and the G305 complex. We also find the 13CO and C2H emissions tend to be brighter in photon dominated regions (PDRs), while N2H+ is brighter in the regions of cold gas that is far away. Furthermore, we make the abundance maps of C2H and N2H+ of cloud A. We find the abundance of C2H is enhanced in the region facing ionizing stars and it decreases steadily moving away from them. On the other hand, the abundance of N2H+ increases from the ionized boundary to the cold gas outward. These phenomena indicate C2H prefers to be produced in hot gas such as PDRs, while N2H+ could be destroyed by it. Our study also suggests the abundance ratio of C2H to N2H+ could trace PDRs in the late stages of massive star formation.

Keywords: Interstellar molecules, Interstellar medium
One-dimensional Force-free Numerical Simulations of Alfvén Waves around a Spinning Black String. We performed one-dimensional force-free magnetodynamic numerical simulations of the propagation of Alfvén waves along magnetic field lines around a spinning black-hole-like object, the Banados-Teitelboim-Zanelli black string, to investigate the dynamic process of wave propagation and energy transport with Alfvén waves. We considered an axisymmetric and stationary magnetosphere and perturbed the background magnetosphere to obtain the linear wave equation for the Alfvén wave mode. The numerical results show that the energy of Alfvén waves monotonically increases as the waves propagate outwardly along the rotating curved magnetic field line around the ergosphere, where energy seems not to be conserved, in the case of energy extraction from the black string by the Blandford-Znajek mechanism. The apparent breakdown of energy conservation suggests the existence of a wave induced by the Alfvén wave. Considering the additional fast magnetosonic wave induced by the Alfvén wave, the energy conservation is confirmed. Similar relativistic phenomena, such as the amplification of Alfvén waves and induction of fast magnetosonic waves, are expected around a spinning black hole.

Keywords: Black hole physics, Plasma astrophysics, Computational methods, Alfven waves, General relativity, Active galactic nuclei, Magnetic fields
Magnetic Spirals in Accretion Flows Originated from Misaligned Magnetic Fields. Misalignment between rotation and magnetic fields has been suggested to be one type of physical mechanism that can ease the effects of magnetic braking during the collapse of cloud cores leading to the formation of protostellar disks. However, its essential factors are poorly understood. Therefore, we perform a more detailed analysis of the physics involved. We analyze existing simulation data to measure the system torques, mass accretion rates, and Toomre Q parameters. We also examine the presence of shocks in the system. While advective torques are generally the strongest, we find that magnetic and gravitational torques can play substantial roles in how angular momentum is transferred during the disk formation process. Magnetic torques can shape the accretion flows, creating two-armed magnetized inflow spirals aligned with the magnetic field. We find evidence of an accretion shock that is aligned according to the spiral structure of the system. Inclusion of ambipolar diffusion as explored in this work has shown a slight influence in the small-scale structures but not in the main morphology. We discuss potential candidate systems where some of these phenomena could be present.

Keywords: Gravitational instability, Magnetohydrodynamics, Star formation, Circumstellar disks, Magnetic fields
Long-term Multiband Optical Variability of Blazar S5 0716+714. Multiband optical photometry data of blazar S5 0716+714 obtained from 2002 to 2019 reveal stable color index change with flux variability. We analyzed this trend under variability caused by the Doppler factor change in the presence of a curved photon energy spectrum. A break in the energy spectrum of emitting electrons, caused by radiative losses, or log-parabolic electron energy distribution, or the synchrotron self-absorption acting in a compact jet part forms such the photon spectrum. We explained the observed color index change with variability by geometric effects only under the assumption that the radiating region is the synchrotron self-absorbed core and the bright optically thin jet. In this framework, we estimated the magnetic field strength in the optically thick part of the radiating region. These values correspond to other independent estimates of the magnetic field near the black hole, further supporting our assumption.

Keywords: Optical observation, Jets, Multi-color photometry, High energy astrophysics, Blazars, Active galactic nuclei
The Strongest Cluster Lenses: An Analysis of the Relation between Strong Gravitational Lensing Strength and the Physical Properties of Galaxy Clusters. Strong gravitational lensing provides unique opportunities to investigate the mass distribution at the cores of galaxy clusters and to study high-redshift galaxies. Using 110 strong-lensing models of 74 cluster fields from the Hubble Frontier Fields (HFF), Reionization Lensing Cluster Survey (RELICS), and Sloan Giant Arcs Survey (SGAS), we evaluate the lensing strength of each cluster (area with ∣μ∣ ≥ 3 for z  s  = 9, normalized to a lens redshift of z = 0.5). We assess how large-scale mass, projected inner-core mass, and the inner slope of the projected mass-density profile relate to lensing strength. While we do identify a possible trend between lensing strength and large-scale mass (Kendall τ = 0.26 and Spearman r = 0.36), we find that the inner slope (50 kpc ≤ r ≤ 200 kpc) of the projected mass-density profile has a higher probability of correlation with lensing strength and can set an upper bound on the possible lensing strength of a cluster (Kendall τ = 0.53 and Spearman r = 0.71). As anticipated, we find that the lensing strength correlates with the effective Einstein area and that a large ( ≳ 30.″0) radial extent of lensing evidence is a strong indicator of a powerful lens. We attribute the spread in the relation to the complexity of individual lensing clusters, which is well captured by the lensing-strength estimator. These results can help us to more efficiently design future observations to use clusters as cosmic telescopes.

Keywords: Galaxy clusters, Strong gravitational lensing
Measuring the Total Ultraviolet Light from Galaxy Clusters at z = 0.5-1.6: The Balance of Obscured and Unobscured Star Formation. Combined observations from UV to IR wavelengths are necessary to fully account for the star formation in galaxy clusters. Low-mass galaxies with ${\rm{log}}({M}_{\ast }/{M}_{\odot })\lt 10$ are typically not individually detected, particularly at higher redshifts (z ~ 1-2) where galaxy clusters are undergoing rapid transitions from hosting mostly active, dust-obscured star-forming galaxies to hosting quiescent, passive galaxies. To account for these undetected galaxies, we measure the total light emerging from GALEX/near-UV stacks of galaxy clusters at z = 0.5-1.6. Combined with existing measurements from Spitzer, WISE, and Herschel, we study the average UV through far-IR spectral energy distribution (SED) of clusters. From the SEDs, we measure the total stellar mass and amount of dust-obscured and unobscured star formation arising from all cluster-member galaxies, including the low-mass population. The relative fraction of unobscured star formation we observe in the UV is consistent with what is observed in field galaxies. There is tentative evidence for lower than expected unobscured star formation at z ~ 0.5, which may arise from rapid redshift evolution in the low-mass quenching efficiency in clusters reported by other studies. Finally, the GALEX data place strong constraints on derived stellar-to-halo mass ratios at z &lt; 1, which anticorrelate with the total halo mass, consistent with trends found from local X-ray observations of clusters. The data exhibit steeper slopes than implementations of the cluster star formation efficiency in semianalytical models.

Keywords: Galaxy clusters, Star formation, Galaxy evolution, High-redshift galaxy clusters
Spatially Decomposed γ-Ray Features Surrounding Supernova Remnant Kes 79 and PSR J1853+0056. There have been substantial improvements on Fermi Large Area Telescope (LAT) data and analysis tools since the last analysis by Auchettl et al. on the intermediate-aged supernova remnant (SNR) Kes 79. Recent multiwavelength studies confirmed its interaction with molecular clouds. About 0.°36 north from Kes 79, a powerful pulsar, PSR J1853+0056, also deserves our attention. In this work, we analyze the 11.5 yr Fermi-LAT data to investigate the γ-ray feature in/around this complex region. Our result shows a more significant detection (~34.8σ in 0.1-50 GeV) for this region. With ≥5 GeV data, we detect two extended sources: Src-N (the brighter one; radius ≈0.°31) concentrated at the north of the SNR while enclosing PSR J1853+0056, and Src-S (radius ≈0.°58) concentrated at the south of the SNR. Their spectra have distinct peak energies (~1.0 GeV for Src-N and ≲0.5 GeV for Src-S), suggesting different origins for them. In our hadronic model that includes the leaked cosmic rays (CRs) from the shock-cloud collision, even with extreme values of parameters, SNR Kes 79 can by no means provide enough CRs reaching clouds at Src-N to explain the local GeV spectrum. We propose that the Src-N emission could be predominantly reproduced by a putative pulsar wind nebula powered by PSR J1853+0056. On the other hand, our same hadronic model can reproduce a majority of the GeV emission at Src-S with typical values of parameters, while the three known pulsars inside Src-S release a total power that is too low to account for half of its γ-ray emission.

Keywords: High energy astrophysics, Cosmic ray astronomy, Pulsars, Supernova remnants, Interstellar clouds, Gamma-ray astronomy
METAL: The Metal Evolution, Transport, and Abundance in the Large Magellanic Cloud Hubble Program. III. Interstellar Depletions, Dust-to-Metal, and Dust-to-Gas Ratios versus Metallicity. The metallicity and gas density dependence of interstellar depletions, the dust-to-gas (D/G), and dust-to-metal (D/M) ratios have important implications for how accurately we can trace the chemical enrichment of the universe, either by using FIR dust emission as a tracer of the ISM or by using spectroscopy of damped Lyα systems to measure chemical abundances over a wide range of redshifts. We collect and compare large samples of depletion measurements in the Milky Way (MW), Large Magellanic Cloud (LMC) (Z = 0.5 Z ⊙), and Small Magellanic Cloud (SMC) (Z = 0.2 Z ⊙). The relations between the depletions of different elements do not strongly vary between the three galaxies, implying that abundance ratios should trace depletions accurately down to 20% solar metallicity. From the depletions, we derive D/G and D/M. The D/G increases with density, consistent with the more efficient accretion of gas-phase metals onto dust grains in the denser ISM. For log N(H) &gt; 21 cm-2, the depletion of metallicity tracers (S, Zn) exceeds -0.5 dex, even at 20% solar metallicity. The gas fraction of metals increases from the MW to the LMC (factor 3) and SMC (factor 6), compensating for the reduction in total heavy element abundances and resulting in those three galaxies having the same neutral gas-phase metallicities. The D/G derived from depletions are respective factors of 2 (LMC) and 5 (SMC) higher than the D/G derived from FIR, 21 cm, and CO emission, likely due to the combined uncertainties on the dust FIR opacity and on the depletion of carbon and oxygen.

Keywords: Gas-to-dust ratio, Galaxy chemical evolution, Interstellar abundances, Interstellar medium, Interstellar dust processes
Habitable Planet Formation around Low-mass Stars: Rapid Accretion, Rapid Debris Removal, and the Essential Contribution of External Giants. In recent years, a paradigm shift has occurred in exoplanet science, wherein low-mass stars are increasingly viewed as a foundational pillar of the search for potentially habitable worlds in the solar neighborhood. However, the formation processes of this rapidly accumulating sample of planet systems are still poorly understood. Moreover, it is unclear whether tenuous primordial atmospheres around these Earth analogs could have survived the intense epoch of heightened stellar activity that is typical for low-mass stars. We present new simulations of in situ planet formation across the M-dwarf mass spectrum, and derive leftover debris populations of small bodies that might source delayed volatile delivery. We then follow the evolution of this debris with high-resolution models of real systems of habitable zone planets around low-mass stars such as TRAPPIST-1, Proxima Centauri, and TOI-700. While debris in the radial vicinity of the habitable zone planets is removed rapidly, thus making delayed volatile delivery highly unlikely, we find that material ubiquitously scattered into an exo-asteroid belt region during the planet-formation process represents a potentially lucrative reservoir of icy small bodies. Thus, the presence of external approximately Neptune-Saturn mass planets capable of dynamically perturbing these asteroids would be a sign that habitable zone worlds around low-mass stars might have avoided complete desiccation. However, we also find that such giant planets significantly limit the efficiency of asteroidal implantation during the planet-formation process. In the coming decade, long-baseline radial velocity studies and Roman Space Telescope microlensing observations will undoubtedly further constrain this process.

Keywords: Exoplanet dynamics, Exoplanets, Asteroid dynamics, Planetary system formation, Low mass stars, Exoplanet formation, Habitable planets, Planet formation
Anisotropic Infall and Substructure Formation in Embedded Disks. The filamentary nature of accretion streams found around embedded sources suggests that protostellar disks experience heterogenous infall from the star-forming environment, consistent with the accretion behavior onto star-forming cores in top-down star-cluster formation simulations. This may produce disk substructures in the form of rings, gaps, and spirals that continue to be identified by high-resolution imaging surveys in both embedded Class 0/I and later Class II sources. We present a parameter study of anisotropic infall, informed by the properties of accretion flows onto protostellar cores in numerical simulations, and varying the relative specific angular momentum of incoming flows as well as their flow geometry. Our results show that anisotropic infall perturbs the disk and readily launches the Rossby wave instability. It forms vortices at the inner and outer edges of the infall zone where material is deposited. These vortices drive spiral waves and angular momentum transport, with some models able to drive stresses corresponding to a viscosity parameter on the order of α ~ 10-2. The resulting azimuthal shear forms robust pressure bumps that act as barriers to radial drift of dust grains, as demonstrated by postprocessing calculations of drift-dominated dust evolution. We discuss how a self-consistent model of anisotropic infall can account for the formation of millimeter rings in the outer disk as well as producing compact dust disks, consistent with observations of embedded sources.

Keywords: Hydrodynamical simulations, Pre-solar nebulae, Hydrodynamics, Planetary system formation, Protoplanetary disks
Influence of the Heliospheric Current Sheet on the Evolution of Solar Wind Turbulence. The effects of the heliospheric current sheet (HCS) on the evolution of Alfvénic turbulence in the solar wind are studied using MHD simulations incorporating the expanding-box model. The simulations show that, near the HCS, the Alfvénicity of the turbulence decreases as manifested by lower normalized cross-helicity and larger excess of magnetic energy. The numerical results are supported by a superposed-epoch analysis using OMNI data, which shows that the normalized cross-helicity decreases inside the plasma sheet surrounding HCS, and the excess of magnetic energy is significantly enhanced at the center of HCS. Our simulation results indicate that the decrease of Alfvénicity around the HCS is due to the weakening of radial magnetic field and the effects of the transverse gradient in the background magnetic field. The magnetic energy excess in the turbulence may be a result of the loss of Alfvénic correlation between velocity and magnetic field and the faster decay of transverse kinetic energy with respect to magnetic energy in a spherically expanding solar wind.

Keywords: Interplanetary turbulence, Solar wind, Magnetohydrodynamical simulations
Periodic Repeating Fast Radio Bursts: Interaction between a Magnetized Neutron Star and Its Planet in an Eccentric Orbit. Fast radio bursts (FRBs) are mysterious transient phenomena. The study of repeating FRBs may provide useful information about their nature due to their redetectability. The two most famous repeating sources are FRBs 121102 and 180916, with a period of 157 days and 16.35 days, respectively. Previous studies suggest that the periodicity of FRBs is likely associated with neutron star (NS) binary systems. Here we introduce a new model which proposes that periodic repeating FRBs are due to the interaction of a NS with its planet in a highly elliptical orbit. The periastron of the planet is very close to the NS so that it would be partially disrupted by tidal force every time it passes through the periastron. Fragments generated in the process could interact with the compact star through the Alfvén wing mechanism and produce FRBs. The model can naturally explain the repeatability of FRBs, with a period ranging from a few days to several hundred days, but it generally requires that the eccentricity of the planet's orbit should be large enough. Taking FRBs 121102 and 180916 as examples, it is shown that the main features of the observed repeating behaviors can be satisfactorily accounted for.

Keywords: Neutron stars, Tidal disruption, Exoplanets, Radio transient sources
Kinematical Analysis of Substructure in the Southern Periphery of the Large Magellanic Cloud. We report the first 3D kinematical measurements of 88 stars in the direction of several recently discovered substructures in the southern periphery of the Large Magellanic Cloud (LMC) using a combination of Gaia proper motions and radial velocities from the APOGEE-2 survey. More specifically, we explore stars in assorted APOGEE-2 pointings in a region of the LMC periphery where various overdensities of stars have previously been identified in maps of stars from Gaia and DECam. By using a model of the LMC disk rotation, we find that a sizable fraction of the APOGEE-2 stars have extreme space velocities that are distinct from, and not a simple extension of, the LMC disk. Using N-body hydrodynamical simulations of the past dynamical evolution and interaction of the LMC and Small Magellanic Cloud (SMC), we explore whether the extreme-velocity stars may be accounted for as tidal debris created in the course of that interaction. We conclude that the combination of LMC and SMC debris produced from their interaction is a promising explanation, although we cannot rule out other possible origins, and that these new data should be used to constrain future simulations of the LMC-SMC interaction. We also conclude that many of the stars in the southern periphery of the LMC lie outside of the LMC plane by several kiloparsecs. Given that the metallicity of these stars suggests that they are likely of Magellanic origin, our results suggest that a wider exploration of the past interaction history of the Magellanic Clouds is needed.

Keywords: Galaxy interactions, Galaxy kinematics, Large Magellanic Cloud
Were the Obliquities in DI Herculis Excited by an Unseen Tertiary Companion?. The eclipsing binary DI Herculis has garnered interest for several decades because of an apparent disagreement between the observed and calculated values of the apsidal precession rate. The problem was resolved when both stars were found to have high obliquities, but the reason for the high obliquities is unknown. Here, we investigate the possibility that the obliquities are (or were) excited by an unseen tertiary star. Obliquity excitation in the current orbital configuration can be ruled out with existing data; any tertiary star that is sufficiently close or massive to overcome the strong spin-orbit coupling of the binary would have been detected through various dynamical effects. It remains possible that the orbit of DI Herculis was initially wider and the obliquity was excited during high-eccentricity tidal migration driven by a tertiary companion, but in this scenario it would be difficult to explain why the observed spin rates are much faster than the pseudo-synchronous rate. In addition, inward migration is most likely to arise when the mass of the perturbing star is comparable to the binary mass, and such a bright tertiary would have been detected in imaging or spectroscopic data. Alternative explanations that do not invoke a tertiary star should be sought for the large obliquities in DI Herculis.

Keywords: Close binary stars, Eclipsing binary stars, Multiple stars, Binary stars
Investigation of the Long-term Variation of Solar Ca II K Intensity. II. Reconstruction of Solar UV Irradiance. Reconstruction of long-term solar UV variations during the entire 20th century is reported. The sunspot number has been used for this purpose so far. By using the full-disk Ca K intensity as an additional solar UV proxy, the range of allowed values for the reconstructed UV irradiance becomes more restricted. We use long-term archival data of the photographic Ca K plates digitized at the Kodaikanal Solar Observatory. The photographic calibration method developed in our previous paper (Paper I) is applied. Various long-term proxy data of solar activity have been used to estimate past UV irradiance. In light of this context, some issues using the historical Ca K data are commented on.

Keywords: Solar cycle, Solar ultraviolet emission, Astronomy data analysis, Solar-terrestrial interactions, Photoheliographs, Solar chromosphere