Sazuna/UAT_keywords huggingface dataset:
Galaxy and Mass Assembly (GAMA): Demonstrating the Power of WISE in the Study of Galaxy Groups to z &lt; 0.1. Combining high-fidelity group characterization from the Galaxy and Mass Assembly survey and source-tailored z &lt; 0.1 photometry from the Wide-Field Infrared Survey Explorer (WISE) survey, we present a comprehensive study of the properties of ungrouped galaxies, compared to 497 galaxy groups (4 ≤ NFoF ≤ 20) as a function of stellar and halo mass. Ungrouped galaxies are largely unimodal in WISE color, the result of being dominated by star-forming, late-type galaxies. Grouped galaxies, however, show a clear bimodality in WISE color, which correlates strongly with stellar mass and morphology. We find evidence for an increasing early-type fraction, in stellar mass bins between 1010 M☉ ≲ Mstellar ≲ 1011 M☉, with increasing halo mass. Using ungrouped, late-type galaxies with star-forming colors (W2-W3 &gt; 3), we define a star-forming main sequence (SFMS), which we use to delineate systems that have moved below the sequence ("quenched" for the purposes of this work). We find that with increasing halo mass, the relative number of late-type systems on the SFMS decreases, with a corresponding increase in early-type, quenched systems at high stellar mass (Mstellar &gt; 1010.5 M☉), consistent with mass quenching. Group galaxies with masses Mstellar &lt; 1010.5 M☉ show evidence of quenching consistent with environmentally driven processes. The stellar mass distribution of late-type, quenched galaxies suggests that it may be an intermediate population as systems transition from being star-forming and late-type to the "red sequence." Finally, we use the projected area of groups on the sky to extract groups that are (relatively) compact for their halo mass. Although these show a marginal increase in their proportion of high-mass and early-type galaxies compared to nominal groups, a clear increase in quenched fraction is not evident.

Keywords: Late-type galaxies, Star formation, Galaxy groups, Infrared galaxies, Galaxy evolution, Galaxy quenching
Mid-infrared Studies of HD 113766 and HD 172555: Assessing Variability in the Terrestrial Zone of Young Exoplanetary Systems. We present multiepoch infrared photometry and spectroscopy obtained with warm Spitzer, Subaru, and the Stratospheric Observatory for Infrared Astronomy to assess variability for the young (∼20 Myr) and dusty debris systems around HD 172555 and HD 113766A. No variations (within 0.5%) were found for the former at either 3.6 or 4.5 μm, while significant nonperiodic variations (peak to peak of ∼10%-15% relative to the primary star) were detected for the latter. Relative to the Spitzer Infrared Spectrograph spectra taken in 2004, multiepoch mid-infrared spectra reveal no change in either the shape of the prominent 10 μm solid-state features or the overall flux levels (no more than 20%) for both systems, corroborating the fact that the population of submicron-size grains that produce the pronounced solid-state features is stable over a decadal timescale. We suggest that these submicron-size grains were initially generated in an optically thick clump of debris of millimeter-size vapor condensates resulting from a recent violent impact between large asteroidal or planetary bodies. Because of the shielding from the stellar photons provided by this clump, intense collisions led to an overproduction of fine grains that would otherwise be ejected from the system by radiation pressure. As the clump is sheared by its orbital motion and becomes optically thin, a population of very fine grains could remain in stable orbits until Poynting-Robertson drag slowly spirals them into the star. We further suggest that the 3-5 μm disk variation around HD 113766A is consistent with a clump/arc of such fine grains on a modestly eccentric orbit in its terrestrial zone.

Keywords: Extrasolar rocky planets, Early-type stars, Exozodiacal dust, Infrared excess, Circumstellar matter, Debris disks
Penetrative Convection for Rotating Boussinesq Flow in Tilted f-planes. In this paper, we have performed linear instability analysis of the penetrative convection for the Boussinesq flow on a tilted f-plane. We have discussed the onset of instability as stationary and oscillatory convection. For the stationary convection, it has been shown that the penetration of convection is hindered by the stability of the upper, less unstable layer. For the oscillatory convection, however, the conclusion is different. We have computed the penetrative convection for both prograde and retrograde waves. The result indicates that for the prograde wave, under certain circumstances, the penetrative convection in the upper layer can be more vigorous than that in the lower unstable layer. For the retrograde wave, on the other hand, the stability in the upper layer always has a negative effect on the penetrative convection. Our calculation on the tilted f-plane has reproduced many features, such as teleconvection and multilayer roll convection, previously discovered on the penetrative convection in the spherical geometry. The dependence of penetrative distance on the Ekman number, the Prandtl number, and the stability parameter has been analyzed.

Keywords: Stellar rotation, Stellar convective zones, Stellar structures
The Impact of Type Ia Supernovae in Quiescent Galaxies. II. Energetics and Turbulence. Type Ia supernovae (SNe Ia) provide unique and important feedback in quiescent galaxies, but their impact has been underappreciated. In this paper, we analyze a series of high-resolution simulations to examine the energetics and turbulence of the medium under SNe Ia. We find that when SN remnants are resolved, their effects differ distinctly from a volumetric heating term, as is commonly assumed in unresolved simulations. First, the net heating is significantly higher than expected, by 30 ± 10% per cooling time. This is because a large fraction of the medium is pushed into lower densities, which cool inefficiently. Second, the medium is turbulent; the root-mean-squared (rms) velocity of the gas to 20-50 km s-1 on a driving scale of tens of parsecs. The velocity field of the medium is dominated by compressional modes, which are larger than the solenoidal components by a factor of 3-7. Third, the hot gas has a very broad density distribution. The ratio between the density fluctuations and the rms Mach number, parameterized as b, is 2-20. This is in contrast to previous simulations of turbulent media, which have found b ≲ 1. The difference is mainly caused by the localized heating of SNe Ia, which creates a large density contrast. Last, the typical length scale of a density fluctuation grows with time, forming increasingly larger bubbles and filamentary ridges. These underlying density fluctuations need to be included when X-ray observations are interpreted.

Keywords: Hydrodynamical simulations, Galaxy formation, Type Ia supernovae, Galaxy evolution, Interstellar medium, Hot ionized medium, Shocks, Elliptical galaxies
On the Granulation and Irregular Variation of Red Supergiants. The mechanisms and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC), and M31. With the time-series data from the All-Sky Automated Survey for SuperNovae and Intermediate Palomar Transient Factory survey, we use the continuous time autoregressive moving average model to estimate the variability features of the light curves and their power spectral density (PSD). The characteristic evolution timescale and amplitude of granulations are further derived from fitting the posterior PSD with the COR function, which is a Harvey-like granulation model. The consistency of theoretical predictions and results is checked to verify the correctness of the assumption that granulations on RSGs contribute to irregular variation. The relations between granulation and stellar parameters are obtained and compared with the results of red giant branch (RGB) stars and Betelgeuse. It is found that the relations are in agreement with predictions from basic physical process of granulation and fall close to the extrapolated relations of RGB stars. The granulations in most of the RSGs evolve at a timescale of several days to a year with a characteristic amplitude of 10-1000 mmag. The results imply that the irregular variations of RSGs can be attributed to the evolution of granulations. When comparing the results from the SMC, LMC, and M31, the timescale and amplitude of granulation seem to increase with metallicity. The analytical relations of the granulation parameters with stellar parameters are derived for the RSG sample of each galaxy.

Keywords: Stellar oscillations, Late-type stars, Red supergiant stars, Stellar pulsations
Formation and Evolution of Compact-object Binaries in AGN Disks. The astrophysical origin of gravitational wave (GW) events discovered by LIGO/VIRGO remains an outstanding puzzle. In active galactic nuclei (AGNs), compact-object binaries form, evolve, and interact with a dense star cluster and a gas disk. An important question is whether and how binaries merge in these environments. To address this question, we have performed one-dimensional N-body simulations combined with a semianalytical model that includes the formation, disruption, and evolution of binaries self-consistently. We point out that binaries can form in single-single interactions through the dissipation of kinetic energy in a gaseous medium. This "gas-capture" binary formation channel contributes up to 97% of gas-driven mergers and leads to a high merger rate in AGN disks even without preexisting binaries. We find the merger rate to be in the range of ∼0.02-60 Gpc-3 yr-1. The results are insensitive to the assumptions on the gaseous hardening processes: we find that once they are formed, binaries merge efficiently via binary-single interactions even if these gaseous processes are ignored. We find that the average number of mergers per black hole (BH) is 0.4, and the probability for repeated mergers in 30 Myr is ∼0.21-0.45. High BH masses due to repeated mergers, high eccentricities, and a significant Doppler drift of GWs are promising signatures that distinguish this merger channel from others. Furthermore, we find that gas-capture binaries reproduce the distribution of low-mass X-ray binaries in the Galactic center, including an outer cutoff at ∼1 pc due to the competition between migration and hardening by gas torques.

Keywords: Black holes, Close binary stars, Gravitational wave sources, Active galactic nuclei, Low-mass x-ray binary stars, N-body simulations
Metal Enrichment in the Circumgalactic Medium and Lyα Halos around Quasars at z ∼ 3. Deep observations have detected extended Lyα emission nebulae surrounding tens of quasars at redshift 2-6. However, the metallicity of such extended halos is still poorly understood. We perform a detailed analysis on a large sample of 80 quasars at z ∼ 3 based on MUSE-VLT data. We find clear evidence of extended emission of the UV nebular lines such as C IV λ1549 or He II λ1640 for about 20% of the sample, while C III] λ1909 is only marginally detected in a few objects. By stacking the cubes, we detect emission of C IV, He II, and C III] out to a radius of about 45 kpc. C IV and He II show a radial decline much steeper than Lyα, while C III] shows a shallower profile similar to Lyα in the inner 45 kpc. We infer that the average metallicity of the circumgalactic gas within the central 30-50 kpc is ∼0.5 solar, or even higher. However, we also find evidence of a component of the Lyα halos, which has much weaker metal emission lines relative to Lyα. We suggest that the high metallicity of the circumgalactic medium within the central 30-50 kpc is associated with chemical pre-enrichment by past quasar-driven outflows and that there is a more extended component of the circumgalactic medium that has much lower metallicity and is likely associated with near-pristine gas accreted from the intergalactic medium. We show that our observational results are in good agreement with the expectations of the FABLE zoom-in cosmological simulations.

Keywords: High-redshift galaxies, Quasars, Circumgalactic medium
BAFFLES: Bayesian Ages for Field Lower-mass Stars. Age is a fundamental parameter of stars, yet in many cases, ages of individual stars are presented without robust estimates of the uncertainty. We have developed a Bayesian framework, BAFFLES, to produce the age posterior for a star from its calcium emission strength (log( ${R}_{{HK}}^{{\prime} }$ )) or lithium abundance (Li EW) and B - V color. We empirically determine the likelihood functions for calcium and lithium as functions of age from literature measurements of stars in benchmark clusters with well-determined ages. We use a uniform prior on age, which reflects a uniform star formation rate. The age posteriors we derive for several test cases are consistent with literature ages found from other methods. BAFFLES represents a robust method to determine the age posterior probability distribution for any field star with 0.45 ≤ B - V ≤ 0.9 and a measurement of ${R}_{{HK}}^{{\prime} }$ and/or 0.35 ≤ B - V ≤ 1.9 and measured Li EW. We compile colors, ${R}_{{HK}}^{{\prime} }$ , and Li EW from over 2630 nearby field stars from the literature, and present the derived BAFFLES age posterior for each star.

Keywords: Field stars, Bayesian statistics, Stellar ages, Stellar activity
Chemically Peculiar A and F Stars with Enhanced s-process and Iron-peak Elements: Stellar Radiative Acceleration at Work. We present ≳15,000 metal-rich ([Fe/H] &gt; -0.2 dex) A and F stars whose surface abundances deviate strongly from solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by their high [Ba/Fe] abundance ratios ([Ba/Fe] &gt; 1.0 dex) in the LAMOST DR5 spectra analyzed by Xiang et al. They are almost exclusively main-sequence and subgiant stars with Teff ≳ 6300 K. Their distribution in the Kiel diagram (Teff- $\mathrm{log}g$ ) traces a sharp border at low temperatures along a roughly fixed-mass trajectory (around 1.4 M⊙) that corresponds to an upper limit in convective envelope mass fraction of around 10-4. Most of these stars exhibit distinctly enhanced abundances of iron-peak elements (Cr, Mn, Fe, Ni) but depleted abundances of Mg and Ca. Rotational velocity measurements from GALAH DR2 show that the majority of these stars rotate slower than typical stars in an equivalent temperature range. These characteristics suggest that they are related to the so-called Am/Fm stars. Their abundance patterns are qualitatively consistent with the predictions of stellar evolution models that incorporate radiative acceleration, suggesting they are a consequence of stellar internal evolution, particularly involving the competition between gravitational settling and radiative acceleration. These peculiar stars constitute 40% of the whole population of stars with mass above 1.5 M⊙, affirming that "peculiar" photospheric abundances due to stellar evolution effects are a ubiquitous phenomenon for these intermediate-mass stars. This large sample of Ba-enhanced, chemically peculiar A/F stars with individual element abundances provides the statistics to test more stringently the mechanisms that alter the surface abundances in stars with radiative envelopes.

Keywords: Stellar processes, Stellar abundances, Am stars, Chemical abundances, Stellar diffusion, Radiative processes, Stellar types, Heavy metal stars, Barium stars, S-process, Chemically peculiar stars, Stellar evolution
Comparing Moment-based and Monte Carlo Methods of Radiation Transport Modeling for Type II-Plateau Supernova Light Curves. Time-dependent electromagnetic signatures from core-collapse supernovae are the result of detailed transport of the shock-deposited and radioactively powered radiation through the stellar ejecta. Due to the complexity of the underlying radiative processes, considerable approximations are made to simplify key aspects of the radiation transport problem. We present a systematic comparison of the moment-based radiation hydrodynamical code STELLA and the Monte Carlo radiation transport code Sedona in the 1D modeling of Type II-Plateau supernovae. Based on explosion models generated from the Modules for Experiments in Stellar Astrophysics instrument, we find remarkable agreements in the modeled light curves and the ejecta structure thermal evolution, affirming the fidelity of both radiation transport modeling approaches. The radiative moments computed directly by the Monte Carlo scheme in Sedona also verify the accuracy of the moment-based scheme. We find that the coarse resolutions of the opacity tables and the numerical approximations in STELLA have an insignificant impact on the resulting bolometric light curves, making it an efficient tool for the specific task of optical light-curve modeling.

Keywords: Core-collapse supernovae, Radiative transfer, Hydrodynamics
Escape and Accretion by Cratering Impacts: Formulation of Scaling Relations for High-speed Ejecta. Numerous small bodies inevitably lead to cratering impacts on large planetary bodies during planet formation and evolution. As a consequence of these small impacts, a fraction of the target material escapes from the gravity of the large body, and a fraction of the impactor material accretes onto the target surface, depending on the impact velocities and angles. Here, we study the mass of the high-speed ejecta that escapes from the target gravity by cratering impacts when material strength is neglected. We perform a large number of cratering impact simulations on a planar rocky target using the smoothed particle hydrodynamics method. We show that the escape mass of the target material obtained from our numerical simulations agrees with the prediction of a scaling law under a point-source assumption when vimp ≳ 12vesc, where vimp is the impact velocity and vesc is the escape velocity of the target. However, we find that the point-source scaling law overestimates the escape mass up to a factor of ∼70, depending on the impact angle, when vimp ≲ 12vesc. Using data obtained from numerical simulations, we derive a new scaling law for the escape mass of the target material for vimp ≲ 12vesc. We also derive a scaling law that predicts the accretion mass of the impactor material onto the target surface upon cratering impacts by numerically evaluating the escape mass of the impactor material. Our newly derived scaling laws are useful for predicting the escape mass of the target material and the accretion mass of the impactor material for a variety of cratering impacts that would occur on large planetary bodies during planet formation.

Keywords: Impact phenomena, Planetary surfaces, Surface processes, Planetary science, Planet formation, Dynamical evolution
SOFIA/FORCAST Observations of R Aqr: Monitoring the Dust Emission. We present mid-infrared spectra of the symbiotic Mira, R Aqr obtained with the Faint Object infraRed CAmera instrument on the Stratospheric Observatory for Infrared Astronomy in 2016 and 2017. These data, supplemented with Infrared Space Observatory observations from 20 yr earlier, allow us to study the variation of the silicate dust emission over short and long timescales. Radiative transfer models for the dust emission from the circumstellar shell indicate that changes that occur within a pulsation period are driven mainly by the variation properties of the asymptotic giant branch star, and do not require any change in the grain composition. The models show that the longer-term changes are due to variations in the dust density, probably modulated by the orbital separation of the binary companion stars. The models also suggest the presence of micron-size dust grains at all epochs.

Keywords: Symbiotic binary stars, Circumstellar dust, Asymptotic giant branch, Stellar pulsations
Chromospheric Magnetic Field: A Comparison of He I 10830 Å Observations with Nonlinear Force-free Field Extrapolation. The nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this condition is considered to be incorrect in the photosphere. We examine direct measurements of the chromospheric magnetic field in two active regions through spectropolarimetric observations at He I 10830 Å, which are compared with the potential fields and NLFFFs extrapolated from the photosphere. The comparisons allow quantitative estimation of the uncertainty in the NLFFF extrapolation from the photosphere. Our analysis shows that observed chromospheric magnetic field may have larger nonpotentiality compared to the photospheric magnetic field. Moreover, the large nonpotentiality in the chromospheric height may not be reproduced by the NLFFF extrapolation from the photospheric magnetic field. The magnitude of the underestimation of the nonpotentiality at chromospheric heights may reach 30°-40° in shear signed angle in some locations. This deviation may be caused by the non-force-freeness in the photosphere. Our study suggests the importance of the inclusion of measured chromospheric magnetic fields in the NLFFF modeling for the improvement of the coronal extrapolation.

Keywords: Spectropolarimetry, Solar photosphere, Solar active regions, Solar magnetic fields, Solar chromosphere
ALMA [{N} {II}] 205 μm Imaging Spectroscopy of the Lensed Submillimeter Galaxy ID 141 at Redshift 4.24. We present an Atacama Large Millimeter/submillimeter Array observation of the Submillimeter galaxy ID 141 at z = 4.24 in the [N II] 205 μm line (hereafter [N II] ) and the underlying continuum at (rest-frame) 197.6 μm. Benefiting from lensing magnification by a galaxy pair at z = 0.595, ID 141 is one of the brightest $z\gt 4$ SMGs. At the angular resolutions of $\sim 1\buildrel{\prime\prime}\over{.} 2$ -1"5 (1″ ∼6.9 kpc), our observation clearly separates and moderately resolves the two lensed images in both continuum and line emission at a signal-to-noise ratio &gt;5. Our continuum-based lensing model implies an averaged amplification factor of ∼5.8 and reveals that the delensed continuum image has a Sérsic index $\simeq 0.95$ and Sérsic radius of ∼0"18 (∼1.24 kpc). Furthermore, the reconstructed [N II] velocity field in the source plane is dominated by a rotation component with a maximum velocity of ∼300 km s-1 at large radii, indicating a dark matter halo mass of ∼10 ${}^{12}{M}_{\odot }$ . This, together with the reconstructed velocity dispersion field being smooth and modest in value (&lt;100 km s-1) over much of the outer parts of the galaxy, favors the interpretation of ID 141 being a disk galaxy dynamically supported by rotation. The observed [N II] /CO (7-6) and [N II] /[C II] 158 μm line-luminosity ratios, which are consistent with the corresponding line ratio versus far-infrared color correlation from local luminous infrared galaxies, imply a delensed star formation rate of (1.8 $\pm \,0.6)\times {10}^{3}{M}_{\odot }$ yr-1 and provide an independent estimate of the size of the star-forming region ${0.7}_{-0.3}^{+0.3}$ kpc in radius.

Keywords: Starburst galaxies, Strong gravitational lensing, Far infrared interferometry, Infrared galaxies, Dust continuum emission, Submillimeter astronomy, High-redshift galaxies