Sazuna/UAT_keywords huggingface dataset:
The Abundance Pattern of α Elements in the Triangulum-Andromeda Overdensity. The close relationship between the nature of the Triangulum-Andromeda (TriAnd) overdensity and the Galactic disk has become increasingly evident in recent years. However, the chemical pattern of this overdensity (RGC = 20-30 kpc) is unique and differs from what we know of the local disk. In this study, we analyze the chemical abundances of five α elements (Mg, O, Si, Ca, and Ti) in a sample of stars belonging to the TriAnd overdensity, including stars with [Fe/H] &lt; -1.2, to investigate the evolution of the α elements with metallicity. High-resolution spectra from Gemini North with GRACES were analyzed. Overall, the TriAnd population presents an α-element pattern that differs from that of the local disk; the TriAnd stars fall in between the local disk and the dwarf galaxies in the [X/Fe] versus [Fe/H] plane. The high [Mg/Fe] ratios obtained for the lower metallicity TriAnd stars may indicate a roughly parallel sequence to the Milky Way local disk at lower values of [Fe/H], revealing a knee shifted toward lower metallicities for the TriAnd population. Similar behavior is also exhibited in the [Ca/Fe] and [Si/Fe] ratios. However, for O and Ti the behavior of the [X/Fe] ratios shows a slight decay with decreasing metallicity. Our results reinforce the TriAnd overdensity as a unique stellar population of the Milky Way, with an abundance pattern that is different from all stellar populations studied to date. The complete understanding of the complex TriAnd population will require high-resolution spectroscopic observations of a larger sample of TriAnd stars.

Keywords: Milky Way disk, Chemical abundances
The Effect of Magnetic Twist and Plasma Flow on the Seismology of Oscillating Flux Tubes. In this paper, we study propagating and standing magnetohydrodynamic kink waves in a magnetically twisted and flowing flux tube. The plasma flow is in the direction of the magnetic field; outside the tube, the magnetic field lines are purely longitudinal. The plasma density is constant both inside and outside the tube, and all stationary quantities vary abruptly at the tube boundary. Using the thin tube and weak twist approximations, the dispersion relation, which determines the dependence of the oscillation frequency on the wavenumber and the stationary quantities of the tube, is found. It is shown that the oscillation frequency of the propagating forward (backward) waves increases (decreases) as the flow speed increases; also, the increase in the magnetic twist increases the oscillation frequency of both forward and backward propagating waves. For very weak magnetic twist, the oscillation frequency of both fundamental mode and first overtone standing waves decreases with increasing flow speed. Our results show that if only the plasma flow or magnetic twist is present in the flux tube, the period ratio P1/P2 of the fundamental mode to the first overtone of the standing kink waves is equal to 2, but if both the plasma flow and magnetic twist are present in the flux tube, the period ratio can be smaller than 2 and support some observational cases. The asymmetry of the wave about the apex point is not affected much by the magnetic twist, but the magnetic twist causes an overestimation of both the flow speed and kink speed of the coronal loop.

Keywords: Solar coronal seismology, Solar coronal heating, Solar corona
Simulations of Early Kilonova Emission from Neutron Star Mergers. We present radiative transfer simulations for blue kilonovae hours after neutron star (NS) mergers by performing detailed opacity calculations for the first time. We calculate atomic structures and opacities of highly ionized elements (up to the 10th ionization) with atomic number Z = 20-56. We find that the bound-bound transitions of heavy elements are the dominant source of the opacities in the early phase (t &lt; 1 day after the merger) and that the ions with a half-closed electron shell provide the highest contributions. The Planck mean opacity for lanthanide-free ejecta (with electron fraction of Ye = 0.30-0.40) can only reach around $\kappa \sim 0.5\mbox{--}1\,{\mathrm{cm}}^{2}\,{{\rm{g}}}^{-1}$ at t = 0.1 days, whereas that increases up to $\kappa \sim 5\mbox{--}10\,{\mathrm{cm}}^{2}\,{{\rm{g}}}^{-1}$ at t = 1 day. The spherical ejecta model with an ejecta mass of Mej = 0.05 M⊙ gives the bolometric luminosity of $\sim 2\times {10}^{42}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ at t ∼ 0.1 days. We confirm that the existing bolometric and multicolor data of GW170817 can be naturally explained by the purely radioactive model. The expected early UV signals reach 20.5 mag at t ∼ 4.3 hr for sources even at 200 Mpc, which is detectable by the facilities such as Swift and the Ultraviolet Transient Astronomy Satellite (ULTRASAT). The early-phase luminosity is sensitive to the structure of the outer ejecta, as also pointed out by Kasen et al. Therefore, the early UV observations give strong constraints on the structure of the outer ejecta and the presence of a heating source besides r-process nuclei.

Keywords: Neutron stars, Radiative transfer
Dynamics of Plasma Turbulence at Earth's Bow Shock and through the Magnetosheath. Earth's magnetosheath can be treated as a natural laboratory to study turbulence development in confined space. The present study focuses on the characteristics of turbulent cascade downstream of the bow shock, where properties of turbulence are known to differ from those in the upstream solar wind. Characteristics of the turbulent spectrum are considered in two distinct points of the magnetosheath for two case studies. The analysis is based on high-resolution measurements of plasma parameters by the Spektr-R spacecraft and magnetic field data by the Themis/Arthemis mission. The measurements are performed for two distinct cases: in the dayside magnetosheath behind the quasi-perpendicular bow shock and in the nightside flank of the magnetosheath behind the quasi-parallel bow shock. The study focuses on the scales at which kinetic effects in plasma become significant and the turbulent spectrum is known to break. The analysis reveals that modification of the fluctuation spectrum at the bow shock is controlled by the distance of the measurement point from the bow shock's nose. Also, performed statistical results suggest the influence of the large-scale parameters of the upstream solar wind and the type of the bow shock on the turbulent spectrum's modification in the downstream region.

Keywords: Interplanetary turbulence, Solar-terrestrial interactions, Magnetohydrodynamics, Solar wind
Chemistry of Protostellar Clumps in the High-mass, Star-forming Filamentary Infrared Dark Cloud G034.43+00.24. To search for the potential chemical dependence on physical conditions, we have carried out the study of chemistry on the nine protostellar clumps of the high-mass star-forming infrared dark cloud G034.43+00.24, with observations of several ∼1 mm lines by the Atacama Pathfinder EXperiment telescope. They include CO/13CO/C18O (2-1), HCO+/H13CO+ (3-2), HCN/H13CN (3-2), HNC (3-2), CS/C34S (5-4), SiO (6-5), SO (6-5), p-H2CO (3-2), and CH3OH (5-4). All the clumps are simply grouped into two classes: high-luminosity protostellar clumps (MM1-MM4, ${L}_{\mathrm{bol}}\gt \sim {10}^{3}$ L⊙) and low-luminosity protostellar clumps (MM5-MM9, ${L}_{\mathrm{bol}}\ll {10}^{3}$ L⊙). Our observations indicate that 13CO suffers either no or low depletion in the clump environment of G034.43+00.24 as characterized by a nearly constant level of the 13CO abundance distribution. For the remaining relatively dense gas tracers, we find that their abundances tend to get enhanced in the high-luminosity protostellar clumps as opposed to the low-luminosity counterparts. We suggest that for most, if not all, of the dense gas tracers the high abundance mainly arises from both the high luminosities and associated outflows of the high-luminosity protostellar clumps while the low abundance could be due to the lack of such active star-forming activities in the low-luminosity protostellar clumps. * This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) under program ID 0104.F-9708. APEX is a collaboration between the Max-Planck-Institut fur Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.

Keywords: Interstellar molecules, Chemical abundances, Astrochemistry, Star formation, Interstellar medium
New Light on an Old Problem of the Cores of Solar Resonance Lines. We reexamine a 50+ yr old problem of deep central reversals predicted for strong solar spectral lines, in contrast to the smaller reversals seen in observations. We examine data and calculations for the resonance lines of H I, Mg II, and Ca II, the self-reversed cores of which form in the upper chromosphere. Based on 3D simulations, as well as data for the Mg II lines from the Interface Region Imaging Spectrograph (IRIS), we argue that the resolution lies not in velocity fields on scales in either of the micro- or macroturbulent limits. Macroturbulence is ruled out using observations of optically thin lines formed in the upper chromosphere, and by showing that it would need to have unreasonably special properties to account for critical observations of the Mg II resonance lines from the IRIS mission. The power in "turbulence" in the upper chromosphere may therefore be substantially lower than earlier analyses have inferred. Instead, in 3D calculations horizontal radiative transfer produces smoother source functions, smoothing out intensity gradients in wavelength and in space. These effects increase in stronger lines. Our work will have consequences for understanding the onset of the transition region, for understanding the energy in motions available for heating the corona, and for the interpretation of polarization data in terms of the Hanle effect applied to resonance line profiles.

Keywords: Solar chromospheric heating, Solar physics, Solar chromosphere, Radiative processes
On the Development of Multidimensional Progenitor Models for Core-collapse Supernovae. Multidimensional hydrodynamic simulations of shell convection in massive stars suggest the development of aspherical perturbations that may be amplified during iron core collapse. These perturbations have a crucial and qualitative impact on the delayed neutrino-driven core-collapse supernova explosion mechanism by increasing the total stress behind the stalled shock. In this paper, we investigate the properties of a 15 ${M}_{\odot }$ model evolved in one, two, and three dimensions (3D) for the final ∼424 s before gravitational instability and iron core collapse using Modules for Experiments in Stellar Astrophysics (MESA) and the FLASH simulation framework. We find that just before collapse, our initially perturbed fully 3D model reaches angle-averaged convective velocity magnitudes of ≈240-260 km s-1 in the Si- and O-shell regions with a Mach number of ≈0.06. We find the bulk of the power in the O-shell resides at large scales, characterized by spherical harmonic orders (ℓ) of 2-4, while the Si-shell shows broad spectra on smaller scales of ${\ell }\approx 30\mbox{--}40$ . Both convective regions show an increase in power at ${\ell }=5$ near collapse. We show that the 1D MESA model agrees with the convective velocity profile and speeds of the Si-shell when compared to our highest resolution 3D model. However, in the O-shell region, we find that MESA predicts speeds approximately four times slower than all of our 3D models suggest. All eight of the multidimensional stellar models considered in this work are publicly available.

Keywords: Stellar interiors, Stellar convective zones, Core-collapse supernovae, Hydrodynamics
Cross-correlation of Far-infrared Background Anisotropies and CMB Lensing from Herschel and Planck Satellites. The cosmic infrared background (CIB) anisotropies and cosmic microwave background (CMB) lensing are powerful measurements for exploring cosmological and astrophysical problems. In this work, we measure the autocorrelation power spectrum of the CIB anisotropies in the Herschel-SPIRE HerMES Large Mode Survey (HeLMS) field, and the cross-power spectrum with the CMB lensing measurements from the Planck satellite. The HeLMS field covers more than 270 deg2, which is much larger than in previous analysis. We use the Herschel Level 1 time stream data to merge the CIB maps at 250, 350, and 500 μm bands, and mask the areas where the flux is greater than $3\sigma \ (\sim 50\,\mathrm{mJy}/\mathrm{beam})$ or there are no measured data. We obtain the final CIB power spectra at 100 ≤ ℓ ≤ 20,000 by considering several effects, such as beam function, mode coupling, transfer function, and so on. We also calculate the theoretical CIB auto- and cross-power spectra of CIB and CMB lensing by assuming that the CIB emissivity follows a Gaussian distribution in redshift. We find that, for the CIB auto-power spectra, we obtain signal-to-noise ratios (S/Ns) of 15.9, 15.7, and 15.3 at 250, 350, and 500 μm, and for the CIB ⨯ CMB lensing power spectra, S/Ns of 7.5, 7.0, and 6.2 at 250, 350, and 500 μm, respectively. Comparing to previous works, the constraints on the relevant CIB parameters are improved by factors of 2- 5 in this study.

Keywords: Cosmology, Large-scale structure of the universe
Calibrating Mg II-based Black Hole Mass Estimators Using Low-to-high-luminosity Active Galactic Nuclei. We present single-epoch black hole mass (MBH) estimators based on the rest-frame ultraviolet (UV) Mg II 2798 Å and optical Hβ 4861 Å emission lines. To enlarge the luminosity range of active galactic nuclei (AGNs), we combine the 31 reverberation-mapped AGNs with relatively low luminosities from Bahk et al., 47 moderate-luminosity AGNs from Woo et al., and 425 high-luminosity AGNs from the Sloan Digital Sky Survey. The combined sample has a monochromatic luminosity at 5100 Å in the range $\mathrm{log}\lambda {L}_{5100}\sim 41.3\mbox{--}46.5$ erg s-1, over the range 5.5 &lt; log(MBH/M⊙) &lt; 9.5. Based on the fiducial mass from the line dispersion or FWHM of Hβ paired with the continuum luminosity at 5100 Å, we calibrate the best-fit parameters in the black hole mass estimators using the Mg II line. We find that the differences in the line profiles between Mg II and Hβ have significant effects on calibrating the UV MBH estimators. By exploring the systematic discrepancy between the UV and optical MBH estimators as a function of AGN properties, we suggest adding a correction term ${\rm{\Delta }}M=-1.44\,{\rm{log}}({{\rm{FWHM}}}_{{\rm{MgII}}}/{\sigma }_{{\rm{MgII}}})+0.33$ in the equation for the UV mass estimator. We also find a ∼0.1 dex bias in the MBH estimation due to the difference in the spectral slope in the range 2800-5200 Å. Depending on whether the selection of MBH estimator is based on either line dispersion or FWHM and either continuum or line luminosity, the derived UV mass estimators show ≳0.1 dex intrinsic scatter with respect to the fiducial Hβ-based MBH.

Keywords: Active galaxies, Active galactic nuclei, Black holes
Dust Masses, Compositions, and Luminosities in the Nuclear Disks and the Diffuse Circumnuclear Medium of Arp 220. We present an analysis of the 4-2600 μm spectral energy distributions (SEDs) of the west and east nuclei and the diffuse infrared (IR) region of the merger-driven starburst Arp 220. We examine several possible source morphologies and dust temperature distributions using a mixture of silicate and carbonaceous grains. From fits to the SEDs we derive dust masses, temperatures, luminosities, and dust-inferred gas masses. We show that the west and east nuclei are powered by central sources deeply enshrouded behind $\sim {10}^{26}$ cm-2 column densities of hydrogen with an exponential density distribution, and that the west and east nuclei are optically thick out to wavelengths of ∼1900 and ∼770 μm, respectively. The nature of the central sources cannot be determined from our analysis. We derive star formation rates (SFRs) or black hole masses needed to power the IR emission, and show that the [C II] 158 μm line cannot be used as a tracer of the SFR in heavily obscured systems. Gas masses inferred from dust are larger than those inferred from CO observations, suggesting either larger dust-to-H mass ratios or the presence of hidden atomic H that cannot be inferred from CO observations. The luminosities per unit mass in the nuclei are ∼450 in solar units, smaller than the Eddington limit of ∼1000-3000 for an optically thick star-forming region, suggesting that the observed gas outflows are primarily driven by stellar winds and supernova shock waves instead of radiation pressure on the dust.

Keywords: Silicate grains, Interacting galaxies, Astrophysical dust processes, Star formation, Carbonaceous grains, Active galactic nuclei, Radiative processes, Ultraluminous infrared galaxies
The Family of Amide Molecules toward NGC 6334I. Amide molecules produced in space could play a key role in the formation of biomolecules on a young planetary object. However, the formation and chemical network of amide molecules in space is not well understood. In this work, Atacama Large Millimeter/submillimeter Array observations are used to study a number of amide(-like) molecules toward the high-mass star-forming region NGC 6334I. The first detections of cyanamide (NH2CN), acetamide (CH3C(O)NH2), and N-methylformamide (CH3NHCHO) are presented for this source. These are combined with analyses of isocyanic acid (HNCO) and formamide (NH2CHO), and a tentative detection of urea (carbamide; NH2C(O)NH2). Abundance correlations show that most amides are likely formed in related reactions occurring in ices on interstellar dust grains in NGC 6334I. However, in an expanded sample of sources, large abundance variations are seen for NH2CN that seem to depend on the source type, which suggests that the physical conditions within the source heavily influence the production of this species. The rich amide inventory of NGC 6334I strengthens the case that interstellar molecules can contribute to the emergence of biomolecules on planets.

Keywords: Astrobiology, Pre-biotic astrochemistry, Astrochemistry
Sequential Lid Removal in a Triple-decker Chain of CME-producing Solar Eruptions. We investigate the onsets of three consecutive coronal mass ejection (CME) eruptions in 12 hr from a large bipolar active region (AR) observed by the Solar Dynamics Observatory (SDO), the Solar Terrestrial Relations Observatory (STEREO), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Geostationary Operational Environmental Satellite (GOES). Evidently, the AR initially had a "triple-decker" configuration: three flux ropes in a vertical stack above the polarity inversion line (PIL). Upon being bumped by a confined eruption of the middle flux rope, the top flux rope erupts to make the first CME and its accompanying AR-spanning flare arcade rooted in a far apart pair of flare ribbons. The second CME is made by eruption of the previously arrested middle flux rope, which blows open the flare arcade of the first CME and produces a flare arcade rooted in a pair of flare ribbons closer to the PIL than those of the first CME. The third CME is made by blowout eruption of the bottom flux rope, which blows open the second flare arcade and makes its own flare arcade and pair of flare ribbons. Flux cancellation observed at the PIL likely triggers the initial confined eruption of the middle flux rope. That confined eruption evidently triggers the first CME eruption. The lid-removal mechanism instigated by the first CME eruption plausibly triggers the second CME eruption. Further lid removal by the second CME eruption plausibly triggers the final CME eruption.

Keywords: Solar flares, The Sun, Solar coronal mass ejections, Solar magnetic fields, Solar filament eruptions, Solar activity
Hunting for Wandering Massive Black Holes. We investigate low-density accretion flows onto massive black holes (BHs) with masses of ≳105 ${M}_{\odot }$ orbiting around in the outskirts of their host galaxies, performing 3D hydrodynamical simulations. Those wandering BHs are populated via ejection from the galactic nuclei through multibody BH interactions and gravitational wave recoils associated with galaxy and BH coalescences. We find that when a wandering BH is fed with hot and diffuse plasma with density fluctuations, the mass accretion rate is limited at ∼10%-20% of the canonical Bondi-Hoyle-Littleton rate owing to a wide distribution of inflowing angular momentum. We further calculate radiation spectra from radiatively inefficient accretion flows onto the wandering BH using a semianalytical two-temperature disk model and find that the predicted spectra have a peak at the millimeter band, where the Atacama Large Millimeter/submillimeter Array (ALMA) has the highest sensitivity and spatial resolution. Millimeter observations with ALMA and future facilities such as the next-generation Very Large Array (ngVLA) will enable us to hunt for a population of wandering BHs and push the detectable mass limit down to M• ≃ 2 × 107 ${M}_{\odot }$ for massive nearby ellipticals, e.g., M87, and M• ≃ 105 ${M}_{\odot }$ for the Milky Way. This radiation spectral model, combined with numerical simulations, will be applied to give physical interpretations of off-nuclear BHs detected in dwarf galaxies, which may constrain BH seed formation scenarios.

Keywords: Accretion, Supermassive black holes, Gravitational waves, Interstellar medium, Radio continuum emission
Recurring Homologous Solar Eruptions in NOAA AR 11429. We present the study of three homologous solar eruptions from NOAA active region (AR) 11429 over four days. This large and complex AR is divided into two relatively simple subregions: northeast (NE) and southwest (SW). Recurrent eruptions occurred from the SW subregion over different evolutionary phases, which provided a unique opportunity to isolate the physical processes responsible for solar eruptions. Persistent shearing and convergence of opposite magnetic polarities led to continuous flux cancellation along the SW polarity inversion line (PIL). A filament persistently lying along the SW PIL was observed to survive each eruption, which suggests a partial eruption of the magnetic system. Further, following the first and second eruptions, a sigmoidal magnetic structure of similar morphology was reformed along the SW PIL. The photospheric motion of magnetic flux continuously injected and stored the negative helicity in the partially erupted magnetic system and built up the magnetic free energy for the successive eruptions. These results suggest that the shearing motion and magnetic flux cancellation of opposite fluxes were: (1) the dominant factor, irrespective of the evolutionary phase, that contributed to the recurrent homologous eruption, and (2) the key processes of forming the erupting structure, likely a magnetic flux rope; its long-lasting continuation results in the reformation of an identical erupting structure. The study also finds that similar magnetic topology could result in the magnetic reconnection at the same location, and such flares during the precursor phase would help in the eruption by decreasing the constraint of the overlying magnetic field.

Keywords: The Sun, Solar flares, Solar coronal mass ejections