Sazuna/UAT_keywords huggingface dataset:
The H<SUB>2</SUB>O Spectrum of the Massive Protostar AFGL 2136 IRS 1 from 2 to 13 μm at High Resolution: Probing the Circumstellar Disk. We have observed the massive protostar AFGL 2136 IRS 1 in multiple wavelength windows in the near- to mid-infrared at high (∼3 km s-1) spectral resolution using VLT+CRIRES, SOFIA+EXES, and Gemini North+TEXES. There is an abundance of H2O absorption lines from the ν1 and ν3 vibrational bands at 2.7 μm, from the ν2 vibrational band at 6.1 μm, and from pure rotational transitions near 10-13 μm. Analysis of state-specific column densities derived from the resolved absorption features reveals that an isothermal absorbing slab model is incapable of explaining the relative depths of different absorption features. In particular, the strongest absorption features are much weaker than expected, indicating optical depth effects resulting from the absorbing gas being well mixed with the warm dust that serves as the "background" continuum source at all observed wavelengths. The velocity at which the strongest H2O absorption occurs coincides with the velocity centroid along the minor axis of the compact disk in Keplerian rotation recently observed in H2O emission with ALMA. We postulate that the warm regions of this dust disk dominate the continuum emission at near- to mid-infrared wavelengths, and that H2O and several other molecules observed in absorption are probing this disk. Absorption line profiles are not symmetric, possibly indicating that the warm dust in the disk that produces the infrared continuum has a nonuniform distribution similar to the substructure observed in 1.3 mm continuum emission.

Keywords: Massive stars, Water vapor, Circumstellar disks
Turbulence and Energetic Particles in Radiative Shock Waves in the Cygnus Loop. I. Shock Properties. We have obtained a contiguous set of long-slit spectra of a shock wave in the Cygnus Loop to investigate its structure, which is far from the morphology predicted by 1D models. Proper motions from Hubble Space Telescope images combined with the known distance to the Cygnus Loop provide an accurate shock speed. Earlier analyses of shock spectra estimated the shock speed, postshock density, temperature, and elemental abundances. In this paper we determine several more shock parameters: a more accurate shock speed, ram pressure, density, compression ratio, dust destruction efficiency, magnetic field strength, and vorticity in the cooling region. From the derived shock properties we estimate the emissivities of synchrotron emission in the radio and pion decay emission in the gamma-rays. Both are consistent with the observations if we assume simple adiabatic compression of ambient cosmic-rays as in the van der Laan mechanism. We also find that, although the morphology is far from that predicted by 1D models and the line ratios vary dramatically from point to point, the average spectrum is matched reasonably well by 1D shock models with the shock speed derived from the measured proper motion. A subsequent paper will analyze the development of turbulence in the cooling zone behind the shock.

Keywords: Supernova remnants, Shocks, Plasma astrophysics, Gamma-rays
Magnetic Imprisonment of Dusty Pinballs by a Supernova Remnant. Motivated by recent measurements of deposits of 60Fe on the ocean floor and the lunar surface, we model the transport of dust grains containing 60Fe from a near-Earth (I.e., within 100 pc) supernova (SN). We inject dust grains into the environment of an SN remnant (SNR) and trace their trajectories by applying a 1D hydrodynamic description assuming spherical symmetry to describe the plasma dynamics, and we include a rudimentary, 3D magnetic field description to examine its influence on charged dust grains. We assume the interstellar medium (ISM) magnetic fields are turbulent and are amplified by the SNR shock, while the SN wind and ejecta fields are negligible. We examine the various influences on the dust grains within the SNR to determine when/if the dust decouples from the plasma, how much it is sputtered, and where within the SNR the dust grains are located. We find that Rayleigh-Taylor instabilities are important for dust survival, as they influence the location of the SN's reverse shock. We find that the presence of a magnetic field within the shocked ISM material limits the passage of SN dust grains, with the field either reflecting or trapping the grains within the heart of the SNR. These results have important implications for in situ 60Fe measurements and for dust evolution in SNRs generally.

Keywords: Supernova dynamics, Astrophysical dust processes, Supernova remnants, Interstellar dust processes, Supernovae
Thermal Formation of Ammonium Carbamate on the Surface of Laboratory Analogs of Carbonaceous Grains in Protostellar Envelopes and Planet-forming Disks. The catalytic role of dust grain surfaces in the thermal reaction CO2 + 2NH3 → NH4+NH2COO- was recently demonstrated by our group. The rate coefficients for the reaction at 80 K on the surface of nanometer-sized carbon and silicate grains were measured to be up to three times higher compared to the reaction rate coefficients measured on KBr. In this study, the reaction was performed on carbon grains and on KBr in the extended temperature range of 50-80 K and with the addition of water ice. The reaction activation energy was found to be about three times lower on grains compared to the corresponding ice layer on KBr. Thus, the catalytic role of the dust grain surface in the studied reaction can be related to a reduction of the reaction barrier. Addition of water to NH3:CO2 ice on grains slowed the reaction down. At the H2O:CO2 ratio of 5:1, the reaction was not detected on the experimental timescale. This result calls into question the thermal formation of ammonium carbamate in dense molecular clouds and outer regions of protostellar and protoplanetary environments with dominating water ice mantle chemistry. However, it can still happen in inner regions of protostellar and protoplanetary environments in crystalline ices.

Keywords: Interstellar dust, Reaction catalysts, Solid matter physics, Laboratory astrophysics, Reaction rates, Astrochemistry, Carbonaceous grains
Disentangling Dust Components in SN 2010jl: The First 1400 Days. The luminous Type IIn SN 2010jl shows strong signs of interaction between the SN ejecta and dense circumstellar material. Dust may be present in the unshocked ejecta; the cool, dense shell (CDS) between the shocks in the interaction region; or in the circumstellar medium (CSM). We present and model new optical and infrared photometry and spectroscopy of SN 2010jl from 82 to 1367 days since explosion. We evaluate the photometric and spectroscopic evolution using the radiative transfer codes MOCASSIN and DAMOCLES, respectively. We propose an interaction scenario and investigate the resulting dust formation scenarios and dust masses. We find that SN 2010jl has been continuously forming dust based on the evolution of its infrared emission and optical spectra. There is evidence for preexisting dust in the CSM as well as new dust formation in the CDS and/or ejecta. We estimate that 0.005-0.01 M☉ of predominantly carbon dust grains has formed in SN 2010jl by ∼1400 days post-outburst.

Keywords: Astronomical models, Dust nebulae, Core-collapse supernovae, Type II supernovae, Extinction, Dust continuum emission, Radiative transfer, Circumstellar shells, Dust shells, Circumstellar dust
A Cross-correlation Study of High-energy Neutrinos and Tracers of Large-scale Structure. The origin of the bulk of the astrophysical neutrinos detected by the IceCube Observatory remains a mystery. Previous source-finding analyses compared the directions of IceCube events and individual sources in astrophysical catalogs. The source association method is technically challenging when the number of source candidates is much larger than the number of the observed astrophysical neutrinos. We show that in this large source number regime, a two-point cross-correlation analysis of neutrino data and source catalog can instead be used to constrain potential source populations for the high-energy astrophysical neutrinos, and provide spatial evidence for the existence of astrophysical neutrinos. We present an analysis of the cross-correlation of the IceCube 2010-2012 point-source data and a WISE-2MASS galaxy sample. While we find no significant detection of cross-correlation with the publicly available neutrino data set, we show that, when applied to the full IceCube data, which has a longer observation time and higher astrophysical neutrino purity, our method has sufficient statistical power to detect a cross-correlation signal if the neutrino sources trace the large-scale structure of the universe.

Keywords: Neutrino astronomy, Large-scale structure of the universe
Plasma β Dependence of Density, Temperatures, and Magnetic-field Correlations of Mirror Structures: Observation and Theory. The mirror structures identified by the depressed or enhanced magnetic field associated with the enhanced or depressed plasma density are widely observed in the solar system plasma. These structures are generated by the mirror instability as a result of sufficiently large temperature anisotropy of T⊥ &gt; T∥. Here, T⊥ and T∥ are, respectively, to be the temperatures perpendicular and parallel to the magnetic field and β = p/(B2/2μ0). Two important observed characteristics are the uneven density-magnetic field compressibility, defined as ${C}_{\rho ,B}=(\delta \rho /\rho)/(\delta B/B)$ , among the various mirror events, and the anticorrelation between the temperatures and magnetic field. This study first shows two mirror structures observed in the magnetosheath with distinct β and ${C}_{\rho ,B}$ . Specifically, β ∼ 6.67, ${C}_{\rho ,B}\sim -0.23$ and β ∼ 1.44, ${C}_{\rho ,B}\sim -0.67$ . The linear kinetic theory is adopted to derive the phase relations for the mirror instability which show an inverse relation between ${C}_{\rho ,B}$ and ${C}_{{T}_{\perp },B}=(\delta {T}_{\perp }/{T}_{\perp })/(\delta B/B)$ , which are negative for various parameter values, and β. While the correlation ${C}_{{T}_{\parallel },B}=(\delta {T}_{\parallel }/{T}_{\parallel })/(\delta B/B)$ may be negative or positive for the mirror unstable and stable parameter regimes, respectively. The theoretical analyses are consistent with the observational results that δT⊥δB &lt; 0 for both events and δT∥δB &lt; 0 is more pronounced for the high β case. The statistical analysis results are summarized by the relationships between ${C}_{\rho ,B}$ , ${C}_{{T}_{\perp },B}$ , ${C}_{{T}_{\parallel },B}$ , and β for six mirror wave events that show high agreements between the observations and theory.

Keywords: Space plasmas, Plasma physics, Solar wind, Alfven waves, Planetary magnetospheres
Meteoroid Bombardment of Lunar Poles. While the floors of deep lunar craters are largely shielded from solar radiation and thus provide an ideal thermal environment for water-ice accumulation, meteoroids on highly inclined orbits can easily access permanently shadowed regions and alter the surface properties via hypervelocity impacts. Here we consider the detailed topography of the lunar poles and a dynamical model of meteoroids to quantify the meteoroid mass fluxes, energy deposition, and impact ejecta mass production rates. Our analysis of regions within 5° from the two lunar poles shows that the variations of the meteoroid mass flux, energy flux, and ejecta production rate are within 50% of their median values. We find that the lunar poles are easily accessible by meteoroid impacts, including the permanently shadowed regions. We find a positive correlation between the surface slope and the meteoroid ejecta production rate, a finding that suggests that a higher impact gardening rate on steep crater walls can facilitate mass wasting.

Keywords: Lunar craters, Micrometeoroids, Space weather, The Moon, Lunar impacts, Lunar surface
Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of Gaia. The orbits of binary stars and planets, particularly eccentricities and inclinations, encode the angular momentum within these systems. Within stellar multiple systems, the magnitude and (mis)alignment of angular momentum vectors among stars, disks, and planets probes the complex dynamical processes guiding their formation and evolution. The accuracy of the Gaia catalog can be exploited to enable comparison of binary orbits with known planet or disk inclinations without costly long-term astrometric campaigns. We show that Gaia astrometry can place meaningful limits on orbital elements in cases with reliable astrometry, and discuss metrics for assessing the reliability of Gaia DR2 solutions for orbit fitting. We demonstrate our method by determining orbital elements for three systems (DS Tuc AB, GK/GI Tau, and Kepler-25/KOI-1803) using Gaia astrometry alone. We show that DS Tuc AB's orbit is nearly aligned with the orbit of DS Tuc Ab, GK/GI Tau's orbit might be misaligned with their respective protoplanetary disks, and the Kepler-25/KOI-1803 orbit is not aligned with either component's transiting planetary system. We also demonstrate cases where Gaia astrometry alone fails to provide useful constraints on orbital elements. To enable broader application of this technique, we introduce the python tool lofti_gaiaDR2 to allow users to easily determine orbital element posteriors.

Keywords: Binary stars, Orbital elements, Orbits, Planetary system formation, Star formation, Astrometric binary stars, Wide binary stars, Exoplanet formation, Orbit determination
HD 145263: Spectral Observations of Silica Debris Disk Formation via Extreme Space Weathering?. We report here time-domain infrared spectroscopy and optical photometry of the HD 145263 silica-rich circumstellar-disk system taken from 2003 through 2014. We find an F4V host star surrounded by a stable, massive 1022-1023 kg (MMoon to MMars) dust disk. No disk gas was detected, and the primary star was seen rotating with a rapid ∼1.75 day period. After resolving a problem with previously reported observations, we find the silica, Mg-olivine, and Fe-pyroxene mineralogy of the dust disk to be stable throughout and very unusual compared to the ferromagnesian silicates typically found in primordial and debris disks. By comparison with mid-infrared spectral features of primitive solar system dust, we explore the possibility that HD 145263's circumstellar dust mineralogy occurred with preferential destruction of Fe-bearing olivines, metal sulfides, and water ice in an initially comet-like mineral mix and their replacement by Fe-bearing pyroxenes, amorphous pyroxene, and silica. We reject models based on vaporizing optical stellar megaflares, aqueous alteration, or giant hypervelocity impacts as unable to produce the observed mineralogy. Scenarios involving unusually high Si abundances are at odds with the normal stellar absorption near-infrared feature strengths for Mg, Fe, and Si. Models involving intense space weathering of a thin surface patina via moderate (T &lt; 1300 K) heating and energetic ion sputtering due to a stellar super-flare from the F4V primary are consistent with the observations. The space-weathered patina should be reddened, contain copious amounts of nanophase Fe, and should be transient on timescales of decades unless replenished.

Keywords: Planetary system formation, Stellar astronomy, Circumstellar matter, Stellar classification, Time domain astronomy, Spectroscopy
Simulating the Fermi Bubbles as Forward Shocks Driven by AGN Jets. The Fermi bubbles are two giant bubbles in gamma-rays lying above and below the Galactic Center (GC). Despite numerous studies on the bubbles, their origin and emission mechanism remain elusive. Here we use a suite of hydrodynamic simulations to study the scenario where the cosmic rays (CRs) in the bubbles are mainly accelerated at the forward shocks driven by a pair of opposing jets from Sgr A*. We find that an active galactic nucleus (AGN) jet event that happened 5-6 Myr ago can naturally reproduce the bilobular morphology of the bubbles, and the postshock gas temperature in the bubbles is heated to ∼0.4 keV, consistent with recent X-ray observations. The forward shocks compress the hot halo gas, and at low latitudes, the compressed gas shows an X-shaped structure, naturally explaining the biconical X-ray structure in the ROSAT 1.5 keV map in both morphology and X-ray surface brightness. CR acceleration is most efficient in the head regions of the bubbles during the first 2 Myr. The opposing jets release a total energy of ∼1055 erg with an Eddington ratio of ∼10-3, which falls well in the range of the hot accretion flow mode for black holes. Our simulations further show that the forward shocks driven by spherical winds at the GC typically produce bubbles with much wider bases than observed and could not reproduce the biconical X-ray structure at low latitudes. This suggests that starburst or AGN winds are unlikely the origin of the bubbles in the shock scenario.

Keywords: Hydrodynamical simulations, Galactic center, Jets, Black holes, High energy astrophysics, Active galaxies, Galaxy jets, Galactic cosmic rays, Shocks, Gamma-rays, Milky Way Galaxy
Type IIP Supernova Progenitors. III. Blue to Red Supergiant Ratio in Low-metallicity Models with Convective Overshoot. The distribution of stars in the Hertzsprung-Russell diagram (HRD) for a stellar conglomeration represents a snapshot of its evolving stellar population. Some of the supergiant stars may transit the HRD from blue to red and then again to blue during their late evolutionary stages, as exemplified by the progenitor of SN 1987 A. Others may transit a given part of the HRD more than twice in a "blue loop" and end up as red supergiants before they explode. Since stars in blue loops spend a considerable part of their lives there, these stages may change the relative number of modeled supergiants in the HRD. Their lifetimes, in turn, depend upon the initial mass of the star, how convection in its interior is modeled, and how much mass loss takes place during its evolution. The observed ratio of the number of blue to red supergiants and yellow to red supergiants sensitively tests the stellar evolution theory. We compare modeled number ratios of these supergiants with observed data from the Large Magellanic Cloud, as it has a metallicity very similar to that of the environment of SN 2013ej. We successfully model these by taking into account moderate (exponential) convective overshooting. We explore its effect on the final radius and mass of the star prior to core collapse. The radius differs dramatically with overshoot. These factors controlling presupernova structure may affect the postexplosion optical/IR light curves and spectral development.

Keywords: Blue loop, Type II supernovae, Massive stars, Stellar evolutionary models, Computational methods, Supergiant stars
The Dragonfly Wide Field Survey. I. Telescope, Survey Design, and Data Characterization. We present a description of the Dragonfly Wide Field Survey (DWFS), a deep photometric survey of a wide area of sky. The DWFS covers 330 deg2 in the equatorial GAMA fields and the Stripe 82 fields in the SDSS g and r bands. It is carried out with the 48-lens Dragonfly Telephoto Array, a telescope that is optimized for the detection of low surface brightness emission. The main goal of the survey is to study the dwarf galaxy population beyond the Local Group. In this paper, we describe the survey design and show early results. We reach 1σ depths of μg ≈ 31 mag arcsec-2 on arcminute scales and show that Milky Way satellites such as Sextans, Bootes, and Ursa Major should be detectable out to D ≳ 10 Mpc. We also provide an overview of the elements and operation of the 48-lens Dragonfly telescope and a detailed description of its data reduction pipeline. The pipeline is fully automated, with individual frames subjected to a rigorous series of quality tests. The sky subtraction is performed in two stages, ensuring that emission features with spatial scales up to ∼0°9 × 0°6 are preserved. The DWFS provides unparalleled sensitivity to low surface brightness features on arcminute scales.

Keywords: Surveys, Dwarf galaxies, Galaxy counts, Automated telescopes, Field galaxies, Galaxies, Low surface brightness galaxies
A Survey of Interplanetary Small Flux Ropes at Mercury. Interplanetary magnetic flux ropes with durations from a few minutes to a few hours have been termed small flux ropes (SFRs). We have built a comprehensive catalog of SFRs at Mercury using magnetometer data from the orbital phase of the MESSENGER mission (2011-2015). In the absence of solar wind plasma measurements, we developed strict identification criteria for SFRs in the magnetometer observations, including force-free field fits for each flux rope. We identified a total of 48 events that met our strict criteria, with events ranging in duration from 2.5 minutes to 4 hr. Using superposed epoch analysis, we obtained the generic SFR magnetic field profile at Mercury. Due to its eccentric orbit, Mercury's heliospheric distance varies between 0.31 and 0.47 au, a range of ∼0.16 au. This distance is potentially large enough for the SFRs to undergo measurable changes due to distance. Thus, we split the data into two distance bins to look for such changes. We found that the average SFR profile is more symmetric farther from the Sun, in line with the idea that SFRs form closer to the Sun and undergo a relaxation process in the solar wind. Based on this result, as well as the SFR durations and the magnetic field strength fall-off with heliocentric distance, we infer that the SFRs observed at Mercury are expanding as they propagate with the solar wind. We also determined that the SFR occurrence frequency is nearly four times as high at Mercury as for similarly detected events at 1 au. Most interestingly, we found two SFR populations in our data set, one likely generated in a quasi-periodic formation process near the heliospheric current sheet, and the other formed away from the current sheet in isolated events.

Keywords: Solar wind, Interplanetary magnetic fields, Heliosphere
A Fully Time-dependent Ab Initio Cosmic-Ray Modulation Model Applied to Historical Cosmic-Ray Modulation. Cosmogenic nuclide records can in principle allow for the estimation of the behavior of the heliospheric magnetic field (HMF) in the distant past. This requires careful modeling of cosmic-ray transport in a manner that is as realistic as possible, taking into account as many of the factors affecting the transport of cosmic-rays (CRs) as possible. The present study presents a 3D time-dependent ab initio CR modulation code that utilizes as inputs simple theoretically and observationally motivated temporal profiles to model large-scale (such as the tilt angle) and small-scale (such as the magnetic variance) parameters relevant to CR transport. Galactic CR proton differential intensities computed using this model for the period 1977-2001 are in reasonable to good agreement with spacecraft observations, reproducing the major salient features of the observed CR intensity temporal profile. To investigate pre-space-age cosmic-ray modulation, and to test conclusions previously drawn regarding the relative importance of drift effects on said modulation, historic estimates of the past HMF presented by McCracken &amp; Beer were used as inputs for the model. The resulting CR temporal intensity profile displays clear evidence of drift effects, with a sharp peak in intensities during the Dalton Minimum.

Keywords: Solar cycle, Heliosphere, Cosmic rays