Sazuna/UAT_keywords huggingface dataset:
The Orion Protostellar Explosion and Runaway Stars Revisited: Stellar Masses, Disk Retention, and an Outflow from the Becklin-Neugebauer Object. The proper motions of the three stars ejected from Orion's OMC1 cloud core are combined with the requirement that their center of mass is gravitationally bound to OMC1 to show that radio source I (Src I) is likely to have a mass around 15 M☉ consistent with recent measurements. Src I, the star with the smallest proper motion, is suspected to be either an astronomical-unit-scale binary or a protostellar merger remnant produced by a dynamic interaction ∼550 yr ago. Near-infrared 2.2 μm images spanning ∼21 yr confirm the ∼55 km s-1 motion of "source X" (Src X) away from the site of stellar ejection and point of origin of the explosive OMC1 protostellar outflow. The radial velocities and masses of the Becklin-Neugebauer (BN) object and Src I constrain the radial velocity of Src X to be ${V}_{\mathrm{LSR}}=-28\pm 10$ km s-1. Several high proper-motion radio sources near BN, including Zapata 11 ([ZRK2004] 11) and a diffuse source near IRc 23, may trace a slow bipolar outflow from BN. The massive disk around Src I is likely the surviving portion of a disk that existed prior to the stellar ejection. Though highly perturbed, shocked, and reoriented by the N-body interaction, enough time has elapsed to allow the disk to relax with its spin axis roughly orthogonal to the proper motion.

Keywords: Stellar-interstellar interactions, Stellar feedback, Plasma jets, Massive stars, Stellar jets, Star formation, Circumstellar disks, Protostars, Runaway stars
Empirical Calibration of the Reddening Maps in the Magellanic Clouds. We present reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), based on color measurements of the red clump. Reddening values of our maps were obtained by calculating the difference of the observed and intrinsic color of the red clump in both galaxies. To obtain the intrinsic color of the red clump, we used reddenings obtained from late-type eclipsing binary systems, measurements for blue supergiants and reddenings derived from Strömgren photometry of B-type stars. We obtained intrinsic color of the red clump (V - I)0 = 0.838 ± 0.034 mag in the LMC, and (V - I)0 = 0.814 ± 0.034 mag in the SMC. We prepared our map with 3' resolution, covering the central part of the LMC and SMC. The mean value of the reddening is E(B - V)LMC = 0.127 mag and E(B - V)SMC = 0.084 mag for the LMC and SMC, respectively. The systematic uncertainty of the average reddening value assigned to each field of our maps is 0.013 mag for both Magellanic Clouds. Our reddening values are on average higher by 0.061 mag for the LMC and 0.054 mag for the SMC, compared with the maps of Haschke et al. We also compared our values with different types of reddening tracers. Cepheids, RR Lyrae stars, early-type eclipsing binaries, and other reddening estimations based on the red clump color on average show reddenings consistent with our map to within a few hundredths of magnitude.

Keywords: Reddened stars, Magellanic Clouds, Interstellar dust extinction
Reconstructing the Observed Ionizing Photon Production Efficiency at z ∼ 2 Using Stellar Population Models. The ionizing photon production efficiency, ξion, is a critical parameter that provides a number of physical constraints to the nature of the early universe, including the contribution of galaxies to the timely completion of the reionization of the universe. Here, we use KECK/MOSFIRE and ZFOURGE multiband photometric data to explore the ξion of a population of galaxies at z ∼ 2 with ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\sim 9.0\mbox{--}11.5$ . Our 130 Hα detections show a median ${\mathrm{log}}_{10}({\XI }_{\mathrm{ion}}[\mathrm{Hz}\,{\mathrm{erg}}^{-1}])$ of 24.8 ± 0.5 when dust corrected using a Calzetti et al. dust prescription. Our values are typical of mass/magnitude selected ξion values observed in the z ∼ 2 universe. Using BPASSv2.2.1 and Starburst99 stellar population models with simple parametric star formation histories (SFH), we find that even with models that account for effects of stellar evolution with binaries/stellar rotation, model galaxies at ${\mathrm{log}}_{10}({\XI }_{\mathrm{ion}}[\mathrm{Hz}\,{\mathrm{erg}}^{-1}])\lesssim 25.0$ have low Hα equivalent widths (EWs) and redder colors compared to our z ∼ 2 observed sample. We find that introducing starbursts to the SFHs resolve the tension with the models; however, due to the rapid time evolution of ξion, Hα EWs, and rest-frame optical colors, our Monte Carlo simulations of starbursts show that random distributions of starbursts in evolutionary time of galaxies are unlikely to explain the observed distribution. Thus, either our observed sample is specially selected based on their past SFH, or stellar models require additional mechanisms to reproduce the observed high UV luminosity of galaxies for a given production rate of hydrogen ionizing photons.

Keywords: Galaxies, High-redshift galaxies, Galaxy evolution, Emission line galaxies
Optical Transmission Spectra of Hot Jupiters: Effects of Scattering. We present new grids of transmission spectra for hot Jupiters by solving the multiple-scattering radiative transfer equations with non-zero scattering albedo instead of using the Beer-Bouguer-Lambert law for the change in the transmitted stellar intensity. The diffused reflection and transmission due to scattering increase the transmitted stellar flux resulting, in a decrease in the transmission depth. Thus, we demonstrate that scattering plays a double role in determining the optical transmission spectra—increasing the total optical depth of the medium and adding the diffused radiation due to scattering to the transmitted stellar radiation. The resulting effects yield an increase in the transmitted flux and hence a reduction in the transmission depth. For a cloudless planetary atmosphere, Rayleigh scattering albedo alters the transmission depth up to about 0.6 μm, but the change in the transmission depth due to forward scattering by cloud or haze is significant throughout the optical and near-infrared regions. However, at wavelengths longer than about 1.2 μm, the scattering albedo becomes negligible, hence the transmission spectra match with that calculated without solving the radiative transfer equations. We compare our model spectra with existing theoretical models and find significant differences at wavelengths shorter than one micron. We also compare our models with observational data for a few hot Jupiters, which may help with constructing better retrieval models in the future.

Keywords: Atmospheric effects, Radiative transfer, Exoplanet atmospheres, Transmission spectroscopy
Sensor Distortion Effects in Photon Monte Carlo Simulations. We present a detailed method to simulating sensor distortions using a photon and electron Monte Carlo method. We use three-dimensional electrostatic simulations to parameterize the perturbed electric field profile for nonideal sensor details. We follow the conversion of simulated photons, and the subsequent response of the converted electrons to the electric field pattern. These nonideal sensor details can be implemented efficiently in a Monte Carlo approach. We demonstrate that the nonideal sensor distortions have a variety of observable consequence including the modification of the astrometric pattern; the distortion of the electron diffusion size and shape; and the distortion of flats. We show analytic validation of the diffusion physics, reproduce two kinds of edge distortion, and show qualitative validation of field-free regions, lithography errors, and fringing. We also demonstrate that there are two related effects of doping variation having different observable consequences. We show that field distortions from accumulated electrons lead to intensity-dependent point-spread functions and the sublinear variance in flats. The method is implemented in the Photon Simulator and the code is publicly available.

Keywords: Astronomical detectors, Computational astronomy, Astronomical instrumentation, Astronomical simulations
Statistical Study of Hard X-Ray Emitting Electrons Associated with Flare-related Coronal Jets. We present the statistical analysis of 33 flare-related coronal jets, and discuss the link between the jet and the flare properties in these events. We selected jets that were observed between 2010 and 2016 by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) that are temporally and spatially associated with flares observed by the Reuven Ramaty High Energy Solar Spectrometric Imager (RHESSI). For each jet, we calculated the jet duration and projected velocity in the plane of sky. The jet duration distribution has a median of 18.8 minutes. The projected velocities are between 31 and 456 km s-1 , with a median at 210 km s-1. For each associated flare, we performed X-ray imaging and spectroscopy and identify nonthermal emission. Nonthermal emission was detected in only 1/4 of the events considered. We did not find a clear correlation between the flare thermal energy or soft X-ray (SXR) peak flux and the jet velocity or jet duration. There is no preferential time delay between the flare and the jet. The X-ray emission is generally located at the base of the jet. The analysis presented in this paper suggests that the flare and jet are part of the same explosive event, that the jet is driven by the propagation of an Alfvénic perturbation, and that the energy partition between flare and jets varies substantially from one event to another.

Keywords: Solar energetic particles, Jets, Solar flares, Solar x-ray flares
Observations of Extreme ICME Ram Pressure Compressing Mercury's Dayside Magnetosphere to the Surface. Mercury's magnetosphere is known to be affected by the enhanced ram pressure and magnetic fields inside interplanetary coronal mass ejections (ICMEs). Here we report detailed observations of an ICME compressing Mercury's dayside magnetosphere to the surface. A fast CME launched from the Sun on 2013 November 29 impacted first the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which was orbiting Mercury, on November 30 and later STEREO-A near 1 au on December 1. Following the ICME impact, MESSENGER remained in the solar wind as the spacecraft traveled inwards and northwards toward Mercury's surface until it reached and passed its closest approach to the planet (at 371 km altitude) without crossing into the magnetosphere. The magnetospheric crossing finally occurred 1 minute before reaching the planet's nightside at 400 km altitude and 84°N latitude, indicating the lack of dayside magnetosphere on this orbit. In addition, the peak magnetic field measured by MESSENGER at this time was 40% above the values measured in the orbits just prior to and after the ICME, a consequence of the magnetospheric compression. Using both a proxy method at Mercury and measurements at STEREO-A, we show that the extremely high ram pressure associated with this ICME was more than high enough to collapse Mercury's weak magnetosphere. As a consequence, the ICME plasma likely interacted with Mercury's surface, evidenced by enhanced sodium ions in the exosphere. The collapse of Mercury's dayside magnetosphere has important implications for the habitability of close-in exoplanets around M dwarf stars, as such events may significantly contribute to planetary atmospheric loss in these systems.

Keywords: Space weather, Solar coronal mass ejections, Mercury (planet)
The Role of Environment in Galaxy Evolution in the SERVS Survey. I. Density Maps and Cluster Candidates. We use photometric redshifts derived from new u-band through 4.5 μm Spitzer IRAC photometry in the 4.8 deg2 of the XMM-LSS field to construct surface density maps in the redshift range of 0.1-1.5. Our density maps show evidence for large-scale structure in the form of filaments spanning several tens of megaparsecs. Using these maps, we identify 339 overdensities that our simulated light-cone analysis suggests are likely associated with dark matter halos with masses, Mhalo, log(Mhalo/M⊙) &gt; 13.7. From this list of overdensities we recover 43 of 70 known X-ray-detected and spectroscopically confirmed clusters. The missing X-ray clusters are largely at lower redshifts and lower masses than our target log(Mhalo/M⊙) &gt; 13.7. The bulk of the overdensities are compact, but a quarter show extended morphologies that include likely projection effects, clusters embedded in apparent filaments, and at least one potential cluster merger (at z ∼ 1.28). The strongest overdensity in our highest-redshift slice (at z ∼ 1.5) shows a compact red galaxy core, potentially implying a massive evolved cluster.

Keywords: Galaxy clusters, Galaxy cluster counts, Redshift surveys, Large-scale structure of the universe
Model-independent Estimations for the Cosmic Curvature from the Latest Strong Gravitational Lensing Systems. Model-independent measurements for the cosmic spatial curvature, which is related to the nature of cosmic spacetime geometry, play an important role in cosmology. On the basis of the distance sum rule in the Friedmann-Lemaître-Robertson-Walker metric, (distance ratio) measurements of strong gravitational lensing (SGL) systems, together with distances from SNe Ia observations, have been proposed to directly estimate the spatial curvature without any assumptions for the theories of gravity and contents of the universe. However, previous studies indicated that a spatially closed universe was strongly preferred. In this paper, we re-estimate the cosmic curvature with the latest SGL data, which includes 163 well-measured systems. In addition, possible factors, e.g., a combination of SGL data from different surveys and stellar masses of the lens galaxy, which might affect estimations for the spatial curvature, are considered in our analysis. We find that, except for the case where only SGL systems from the Sloan Lens ACS Survey are considered, a spatially flat universe is consistently favored at very high confidence levels by the latest observations. It has been suggested that an increasing number of well-measured strong lensing events might significantly reduce the bias of estimation for the cosmic curvature.

Keywords: Galaxy distances, Observational cosmology, Gravitational lensing, Cosmological parameters
Hi-C 2.1 Observations of Small-scale Miniature-filament-eruption-like Cool Ejections in an Active Region Plage. We examine 172 Å ultra-high-resolution images of a solar plage region from the High-Resolution Coronal Imager, version 2.1 (Hi-C 2.1, or Hi-C) rocket flight of 2018 May 29. Over its five minute flight, Hi-C resolved a plethora of small-scale dynamic features that appear near noise level in concurrent Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) 171 Å images. For 10 selected events, comparisons with AIA images at other wavelengths and with Interface Region Imaging Spectrograph (IRIS) images indicate that these features are cool (compared to the corona) ejections. Combining Hi-C 172 Å, AIA 171 Å, IRIS 1400 Å, and Hα, we see that these 10 cool ejections are similar to the Hα "dynamic fibrils" and Ca II "anemone jets" found in earlier studies. The front of some of our cool ejections are likely heated, showing emission in IRIS 1400 Å. On average, these cool ejections have approximate widths 3"2 ± 2"1, (projected) maximum heights and velocities 4"3 ± 2"5 and 23 ± 6 km s-1, and lifetimes 6.5 ± 2.4 min. We consider whether these Hi-C features might result from eruptions of sub-minifilaments (smaller than the minifilaments that erupt to produce coronal jets). Comparisons with SDO's Helioseismic and Magnetic Imager (HMI) magnetograms do not show magnetic mixed-polarity neutral lines at these events' bases, as would be expected for true scaled-down versions of solar filaments/minifilaments. But the features' bases are all close to single-polarity strong-flux-edge locations, suggesting possible local opposite-polarity flux unresolved by HMI. Or it may be that our Hi-C ejections instead operate via the shock-wave mechanism that is suggested to drive dynamic fibrils and the so-called type I spicules.

Keywords: Solar active region magnetic fields, Solar atmospheric motions, Active solar chromosphere
BreakBRD Galaxies. I. Global Properties of Spiral Galaxies with Central Star Formation in Red Disks. We introduce a collection of primarily centrally star-forming galaxies that are selected by disk color to have truncated disk star formation. We show that common explanations for centrally concentrated star formation—low stellar mass, bars, and high-density environments—do not universally apply to this sample. To gain insight into our sample, we compare these galaxies to a parent sample of strongly star-forming galaxies and to a parent sample of galaxies with low specific star formation rates. We find that in star formation and color space from ultraviolet to the infrared these galaxies either fall between the two samples or agree more closely with galaxies with high specific star formation rates. Their morphological characteristics also lie between high and low specific star formation rate galaxies, although their Petrosian radii agree well with that of the low specific star formation rate parent sample. We discuss whether this sample is likely to be quenching or showing an unusual star formation distribution while continuing to grow through star formation. Future detailed studies of these galaxies will give us insights into how the local conditions within a galaxy balance environmental influence to govern the distribution of star formation. In this first paper in a series, we describe the global properties that identify this sample as separate from more average spiral galaxies, and we identify paths forward to explore the underlying causes of their differences.

Keywords: Quenched galaxies, Spiral galaxies, Galaxy environments, Galaxy physics, Galaxy evolution, Extragalactic astronomy, Galaxy quenching, Galaxy processes
Direct Detection of Black Hole-driven Turbulence in the Centers of Galaxy Clusters. Supermassive black holes (SMBHs) are thought to provide energy that prevents catastrophic cooling in the centers of massive galaxies and galaxy clusters. However, it remains unclear how this "feedback" process operates. We use high-resolution optical data to study the kinematics of multiphase filamentary structures by measuring the velocity structure function (VSF) of the filaments over a wide range of scales in the centers of three nearby galaxy clusters: Perseus, A2597, and Virgo. We find that the motions of the filaments are turbulent in all three clusters studied. There is a clear correlation between features of the VSFs and the sizes of bubbles inflated by SMBH-driven jets. Our study demonstrates that SMBHs are the main driver of turbulent gas motions in the centers of relaxed galaxy clusters and suggests that this turbulence is an important channel for coupling feedback to the environment. Our measured amplitude of turbulence is in good agreement with Hitomi Doppler line broadening measurement and X-ray surface-brightness fluctuation analysis, suggesting that the motion of the cold filaments is well-coupled to that of the hot gas. The smallest scales that we probe are comparable to the mean free path in the intracluster medium. Our direct detection of turbulence on these scales provides the clearest evidence to date that isotropic viscosity is suppressed in the weakly collisional, magnetized intracluster plasma.

Keywords: Galaxy clusters, Supermassive black holes, Galaxy physics, Intracluster medium
Case Study of Solar Wind Suprathermal Electron Acceleration at the Earth's Bow Shock. We present a case study of the in situ acceleration of solar wind suprathermal electrons at the two quasi-perpendicular-bow-shock crossings on 2015 November 4, combining the Wind 3D Plasma and Energetic Particle measurements of ambient solar wind suprathermal electrons and Magnetospheric Multiscale mission measurements of shocked suprathermal electrons. In both cases, the omnidirectional differential fluxes of shocked suprathermal electrons in the downstream exhibit a double-power-law energy spectrum with a spectral index of ∼3 at energies below a downward break ɛbrk near 40 keV and index of ∼6 at energies above, different from the unshocked suprathermal electrons observed in the ambient solar wind. At energies below (above) ɛbrk, the observed electron flux ratio between the downstream and ambient solar wind, JD/JA, peaks near 90° PA (becomes roughly isotropic). Electrons at ɛbrk have an average electron gyrodiameter (across bow shock) comparable to the shock thickness. These suggest that the bow-shock acceleration of suprathermal electrons is likely dominated by the shock drift acceleration mechanism. For electrons at energies below (above) ɛbrk, their estimated drift time appears to be roughly energy independent (decrease with energy), leading to the formation of a double-power-law spectrum substantially steepening at a break that's determined by the shock thickness.

Keywords: Shocks
Dynamical Structure of Small Bulges Reveals Their Early Formation in ΛCDM Paradigm. The Λ cold dark matter (ΛCDM) paradigm of galaxy formation predicts that dense spheroidal stellar structures invariably grow at early cosmic time. These primordial spheroids evolve toward a virialized dynamical status as they finally become today's elliptical galaxies and large bulges at the center of disk galaxies. However, observations reveal that small bulges in spiral galaxies are common in the nearby universe. The prevailing belief that all small bulges form at later times from internal processes occurring in the disk represents a challenge for the ΛCDM scenario. Notably, the coevolution of bulges and central supermassive black holes (SMBHs) at early phases of galaxy evolution is also at stake. However, observations have so far not provided conclusive evidence against their possible early origin. Here, we report new observations of small bulges showing that they follow the mass-velocity dispersion relation expected for virialized systems. Contrary to previous claims, small bulges bridge the gap between massive ellipticals and globular clusters. This dynamical picture supports a scenario where systems over seven orders of magnitude in stellar mass form at early cosmic time. These results alleviate the tension between ΛCDM simulations and observations at galactic scales. We hypothesize that these small bulges are actually the low-mass descendants of compact objects observed at high redshift, also known as red nuggets, which are consistently produced in cosmological ΛCDM simulations. Therefore, this also suggests that the established coevolution of SMBHs and large bulges naturally extends to spheroids in the low-mass regime.

Keywords: Galaxy formation, Late-type galaxies, Disk galaxies, Compact galaxies, Galaxy properties, Galaxy physics, Early-type galaxies, Galaxy dynamics, Galaxy structure, Elliptical galaxies, Galaxies, Low surface brightness galaxies