Sazuna/UAT_keywords huggingface dataset:
Solar Filaments and Interplanetary Magnetic Field B<SUB>z</SUB>. The direction of the axis of an interplanetary coronal mass ejection (ICME) plays an important role in determining if it will cause a geomagnetic disturbance in the Earth's magnetosphere upon impact. Long period southward-pointing ICME fields are known to cause significant space weather impacts and thus geomagnetic storms. We present an extensive analysis of CME-ICME directionality using 86 halo-CMEs observed between 2007 and 2017 to compare the direction of the source filament axial magnetic field on the Sun and the direction of the interplanetary magnetic field near the Earth at the L1 Lagrangian point. Excluding 12 cases that were too ambiguous to determine, for the remaining 74 ICMEs, we find an agreement in terms of the northward/southward orientation of Bz between ICMEs and their CME source regions in 85% of cases. Some of the previous studies discussed here have obtained an agreement of 77% and 55%. We therefore suggest that our method can be meaningful as a first step in efficiently predicting geoeffective ICMEs by observing and analyzing the source regions of CMEs on the Sun.

Keywords: Space weather, Solar filaments, Solar coronal mass ejections
Orphan GRB Afterglow Searches with the Pan-STARRS1 COSMOS Survey. We present the result of a search for orphan gamma-ray burst (GRB) afterglows in the Pan-STARRS1 (PS1) COSMOS survey. There is extensive theoretical and observational evidence suggesting that GRBs are collimated jets; the direct observation of orphan GRB afterglows would further support this model. An optimal survey strategy is designed by coupling the PS1 survey with the Subaru/Hyper-Suprime-Cam (HSC) survey. The PS1 COSMOS survey, one of the survey fields in the PS1 Medium Deep Survey (PS1/MDS), searches a field of 7 deg2 from 2011 December to 2014 January, reaching a limiting magnitude R ∼ 23. The dense cadence of PS1/MDS is crucial for identifying transients, and the deep magnitude reached by the HSC survey (R ∼ 26) is important for evaluating potential GRB hosts. A transient classification method is employed to select potential orphan GRB afterglow candidates. After a thorough analysis of the transient and host galaxy properties, we conclude that there are no candidates in this survey field. The null result implies that the consideration of jet structures is essential for further orphan GRB afterglow surveys.

Keywords: Transient sources, Gamma-ray bursts, Time domain astronomy
The Spin-period History of Intermediate Polars. We report the detailed history of spin-period changes in five intermediate polars (DQ Herculis, AO Piscium, FO Aquarii, V1223 Sagittarii, and BG Canis Minoris) during the 30-60 yr since their original discovery. Most are slowly spinning up, although there are sometimes years-long episodes of spin-down. This is supportive of the idea that the underlying magnetic white dwarfs are near spin equilibrium. In addition to the ∼40 stars sharing many properties and defined by their strong, pulsed X-ray emission, there are a few rotating much faster (P &lt; 80 s), whose membership in the class is still in doubt—and who are overdue for closer study.

Keywords: Close binary stars, Interacting binary stars, Novae, DQ Herculis stars, Stellar accretion, Stellar accretion disks, Cataclysmic variable stars, Classical novae
Planes of Satellites around Simulated Disk Galaxies. I. Finding High-quality Planar Configurations from Positional Information and Their Comparison to MW/M31 Data. We address the "plane of satellites problem" by studying planar configurations around two disk galaxies with no late major mergers, formed in zoom-in hydro-simulations. Due to the current lack of good-quality kinematic data for M31 satellites, we use only positional information. So far, positional analyses of simulations are unable to find planes as thin and populated as the observed ones. We follow a novel systematic and detailed plane searching technique to study the properties and quality of planes of satellites, in both simulations or real data. In particular, (I) we extend the four-galaxy-normal density plot method (Pawlowski et al. 2013) in a way designed to efficiently identify high-quality planes (I.e., thin and populated) without imposing extra constraints on their properties, and (II), we apply it for the first time to simulations. Using zoom-in simulations allows us to mimic Milky Way/M31-like systems regarding the number of satellites involved as well as galactic disk effects. In both simulations, we find satellite planar configurations that are compatible, along given time intervals, with all of the spatial characteristics of observed planes identified using the same methodology. During most of these periods, planes are approximately perpendicular to the galactic disk. However, the fraction of co-orbiting satellites within them is, in general, low, suggesting time-varying satellite membership. We conclude that high-quality positional planes of satellites could be not infrequent in ΛCDM-formed disk galaxies with a quiet assembly history. Detecting kinematically coherent, time-persistent planes demands considering the full six-dimensional phase-space information of satellites.

Keywords: Local Group, Galaxy planes, Galaxy dynamics, Dwarf galaxies, Galaxy kinematics
Earths in Other Solar Systems' N-body Simulations: The Role of Orbital Damping in Reproducing the Kepler Planetary Systems. The population of exoplanetary systems detected by Kepler provides opportunities to refine our understanding of planet formation. Unraveling the conditions needed to produce the observed exoplanet systems will allow us to make informed predictions as to where habitable worlds exist within the galaxy. In this paper, we examine, using N-body simulations, how the properties of planetary systems are determined during the final stages of assembly, when planets accrete from embryos and planetesimals. While accretion is a chaotic process, trends emerge allowing certain features of an ensemble of planetary systems to provide a memory of the initial distribution of solid mass around a star prior to accretion. We also use epos, the Exoplanet Population Observation Simulator, to account for detection biases and show that different accretion scenarios can be distinguished from observations of the Kepler systems. We show that the period of the innermost planet, the ratio of orbital periods of adjacent planets, and masses of the planets are determined by the total mass and radial distribution of embryos and planetesimals at the beginning of accretion. In general, some amount of orbital damping, via either planetesimals or gas, during accretion is needed to match the whole population of exoplanets. Surprisingly, all simulated planetary systems have planets that are similar in size, showing that the "peas in a pod" pattern can be consistent with both a giant impact scenario and a planet migration scenario. The inclusion of material at distances larger than what Kepler observes (&gt;1 au) has a profound impact on the observed planetary architectures and thus on the formation and delivery of volatiles to possible habitable worlds.

Keywords: Exoplanet dynamics, Exoplanets, Planetary system formation, Exoplanet formation, N-body simulations, Planet formation
AstroSat Observations of GRO J2058+42 during the 2019 Outburst. We present results from AstroSat observations of the recent outburst of GRO J2058+42, an X-ray pulsar in a Be-binary system. The source was observed by the LAXPC and SXT instruments on AstroSat on 2019 April 10 during the declining phase of its latest giant outburst. Light curves showed a strong pulsation of the pulsar with a period of 194.2201 ± 0.0016 s and a spin-up rate of (1.65 ± 0.06) × 10-11 Hz s-1. Intermittent flaring was detected in light curves between the 3 and 80 keV energy bands, with an increase in intensity of up to 1.8 times its average intensity. Pulse profiles obtained between the 3 and 80 keV energy bands of the pulsar showed strong dependence on energy. During AstroSat observations, a broad peak was consistently observed in the power density spectrum of the source with a peak oscillation frequency of 0.090 Hz along with its higher harmonics, which may be due to quasi-periodic oscillations, a commonly observed phenomenon in transient X-ray pulsars during their outburst. AstroSat observations also detected cyclotron absorption features in its spectrum corresponding to (9.7-14.4) keV, (19.3-23.8) keV, and (37.8-43.1) keV. The pulse-phase-resolved spectroscopy of the source showed a phase-dependent variation in its energy and the relative strength of these features. The spectrum was well fitted with an absorbed blackbody, Fermi-Dirac cutoff model and alternatively with an absorbed CompTT model. Both of these models were combined with an Fe line and three Gaussian absorption lines to account for the observed cyclotron resonance scattering features in the spectrum.

Keywords: Neutron stars, High mass x-ray binary stars, X-ray sources, Be stars, Binary pulsars
G15.684-0.29: One of the Largest Galactic Infrared Bubbles Showing Strong Evidence of Triggered Star Formation. The bubble G15.684-0.29 has a radius of 15.7 pc. Its large size indicates that it may have enough time to trigger star formation. We identify 39 dense cold clumps around the bubble from the Hi-GAL survey. All of them satisfy the criteria for forming massive stars, and most of them lie in the bubble shell. We identify 19 molecular clumps around the bubble from the 12CO(3-2) survey, all of which are gravitationally bound. We found 9 Class I YSOs, 28 Class II YSOs, and 12 transition disks (TDs) around the bubble. For those young stellar objects (YSOs) located within the bubble boundary, 6 of 7 Class I YSOs lie in the shell, 15 of 22 Class II YSOs lie inside the bubble, and 3 of 5 TDs lie inside the bubble. The dynamical age of G15.684-0.29 in a turbulent medium is ∼4 Myr, which is much greater than the shell fragmentation time, ∼0.82-1.74 Myr. We suggest that triggered star formation may be ongoing in the shell of the bubble, and the collect and collapse model may work here. However, we cannot rule out the possibility that the radiation-driven implosion model may work on the formation of some YSOs. As we expected, the larger bubble has a much longer dynamical age, but we failed to find a clear age gradient for YSOs around the bubble.

Keywords: Molecular clouds, Star formation, Interstellar medium, CO line emission, Dust shells, H II regions
Rotationally Inelastic Collisions of CN<SUP>-</SUP> with He: Computing Cross Sections and Rates in the Interstellar Medium. A newly calculated ab initio potential energy surface is used to compute collision-driven state-changing cross sections and rate coefficients over a range from 5 to 100 K for CN-(1Σ), the smallest anion detected in the interstellar medium, interacting with He, an abundant species in this environment. We compare our presently computed rate coefficients with those previously published for the similar and important systems CN-He, CN-H2, and CN--H2 to illustrate the broader network of inelastic, state-changing processes for these four systems. We also discuss the size-scaling effects that occur when changing partners from He to H2. We further analyze the differences in size between collision-driven rate coefficients when going from neutral CN to its anion. All the present results are discussed in detail, to provide accurate and realistic data for chemical networks that wish to include the CN- anion in their modeling of astrochemical environments.

Keywords: De-excitation rates, Molecular clouds, Collision physics, Molecular physics, Excitation rates, Radiative processes, Diffuse molecular clouds
Conditions for Chromospheric Plasma Acceleration or Trigger of Chromospheric Mass Ejections by Magnetic-field-aligned Electric Fields. Backward-propagating or reverse fluctuations in Alfvénic turbulence were recently found to produce magnetic-field-aligned (MFA) electric fields that can easily transfer their energy to the plasma, either in the form of heat (or electron beams that quickly dissipate their energy as heat) if electrons absorb most of the MFA energy, or in the form of translational motion of the plasma if the ions absorb most of the MFA energy. Conditions for the direct proton acceleration (jet formation) in the quiet chromosphere included a temperature ≤104 K and a magnetic field between about 10 and 100 G, conditions very similar to those under which chromospheric plasma jets or dynamic jet-like spicules are observed with the Interface Region Imaging Spectrograph. Here the conditions for direct ion acceleration by MFA electric fields are determined for a much broader range of electron densities and plasma temperatures, to include both quiet and flaring conditions of the chromospheric plasma. For the higher chromospheric electron densities of solar flaring conditions, direct ion and therefore plasma acceleration by MFA electric fields is found to be possible in the much stronger (kG) magnetic fields of active regions, provided the plasma temperature remains less than about 105 K. Under flaring conditions, the MFA electric fields may cause the acceleration or at least trigger the upward motion of dense (&gt;1012-1013 cm-3) chromospheric plasma. It is also suggested that chromospheric nonresonant MFA acceleration, by producing local electron beams, may eliminate the need for electron beams to propagate from the flaring corona down to the denser chromosphere.

Keywords: Solar flares, Plasma astrophysics, Solar physics, Alfven waves, Solar coronal mass ejections, Solar transition region, Solar chromosphere, Magnetic fields
Can the Cosmological Dilation Explain the Skewness in the Gamma-Ray Burst Duration Distribution?. In order to explain the origin of skewness in the gamma-ray burst (GRB) duration distribution, a statistical model, based on the cosmological time dilation and taking into account the GRB formation rate and instrumental effects, is examined. It is concluded that the considered effects are able to account for only a small fraction of the observed skewness. Therefore, its origin needs to be searched for in the processes governing the progenitors of GRBs​.

Keywords: Cosmology, Gamma-ray bursts, Astronomy data analysis, Astrostatistics
The R-process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5-455510. We report on the spectroscopic analysis of RAVE J183013.5-455510, an extremely metal-poor star, highly enhanced in CNO, and with discernible contributions from the rapid neutron-capture process. There is no evidence of binarity for this object. At $[\mathrm{Fe}/{\rm{H}}]$ = -3.57, this star has one of the lowest metallicities currently observed, with 18 measured abundances of neutron-capture elements. The presence of Ba, La, and Ce abundances above the solar system r-process predictions suggests that there must have been a non-standard source of r-process elements operating at such low metallicities. One plausible explanation is that this enhancement originates from material ejected at unusually high velocities in a neutron star merger event. We also explore the possibility that the neutron-capture elements were produced during the evolution and explosion of a rotating massive star. In addition, based on comparisons with yields from zero-metallicity faint supernova, we speculate that RAVE J1830-4555 was formed from a gas cloud pre-enriched by both progenitor types. From analysis based on Gaia DR2 measurements, we show that this star has orbital properties similar to the Galactic metal-weak thick-disk stellar population. * Based on observations gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 099.D-0428(A).

Keywords: Stellar kinematics, R-process, Chemical abundances, CEMP stars, Metallicity, Stellar atmospheres
New Constraints on the Origin of Surface Brightness Profile Breaks of Disk Galaxies from MaNGA. In an effort to probe the origin of surface brightness profile (SBP) breaks widely observed in nearby disk galaxies, we carry out a comparative study of stellar population profiles of 635 disk galaxies selected from the Mapping Nearby Galaxies at Apache Point Observatory spectroscopic survey. We classify our galaxies into single exponential (T I), down-bending (T II), and up-bending (T III) SBP types and derive their spin parameters and radial profiles of age/metallicity-sensitive spectral features. Most T II (T III) galaxies have down-bending (up-bending) star formation rate (SFR) radial profiles, implying that abrupt radial changes of SFR intensities contribute to the formation of both T II and T III breaks. Nevertheless, a comparison between our galaxies and simulations suggests that stellar migration plays a significant role in weakening down-bending Σ⋆ profile breaks. While there is a correlation between the break strengths of SBPs and age/metallicity-sensitive spectral features for T II galaxies, no such correlation is found for T III galaxies, indicating that stellar migration may not play a major role in shaping T III breaks, as is also evidenced by a good correspondence between the break strengths of Σ⋆ and SBPs of T III galaxies. We do not find evidence for galaxy spin being a relevant parameter for forming different SBP types, nor do we find significant differences between the asymmetries of galaxies with different SBP types, suggesting that environmental disturbances or satellite accretion in the recent past do not significantly influence the break formation. By dividing our sample into early and late morphological types, we find that galaxies with different SBP types follow nearly the same tight stellar mass- ${R}_{25}$ relation, which makes the hypothesis that stellar migration alone can transform SBP types from T II to T I and then to T III highly unlikely.

Keywords: Galaxies, Spiral galaxies, Galaxy evolution, Disk galaxies
Continuum-fitting the X-Ray Spectra of Tidal Disruption Events. We develop a new model for X-ray emission from tidal disruption events (TDEs), applying stationary general relativistic "slim disk" accretion solutions to supermassive black holes (SMBHs) and then ray-tracing the photon trajectories from the image plane to the disk surface, including gravitational redshift, Doppler, and lensing effects self-consistently. We simultaneously and successfully fit the multi-epoch XMM-Newton X-ray spectra for two TDEs: ASASSN-14li and ASASSN-15oi. We test explanations for the observed, unexpectedly slow X-ray brightening of ASASSN-15oi, including delayed disk formation and variable obscuration by a reprocessing layer. We propose a new mechanism that better fits the data: a "slimming disk" scenario in which accretion onto an edge-on disk slows, reducing the disk height and exposing more X-rays from the inner disk to the sightline over time. For ASASSN-15oi, we constrain the SMBH mass to ${4.0}_{-3.1}^{+2.5}\times {10}^{6}{M}_{\odot }$ . For ASASSN-14li, the SMBH mass is ${10}_{-7}^{+1}\times {10}^{6}{M}_{\odot }$ , and the spin is &gt;0.3. For both TDEs, our fitted masses are consistent with independent estimates; for ASASSN-14li, application of the external mass constraint narrows our spin constraint to &gt;0.85. The mass accretion rate of ASASSN-14li decays slowly, as ∝t-1.1, perhaps due to inefficient debris circularization. Over ≍1100 days, its SMBH has accreted ∆M ≍ 0.17M☉, implying a progenitor star mass of &gt;0.34M☉, I.e., no "missing energy problem." For both TDEs, the hydrogen column density declines to the host galaxy plus Milky Way value after a few hundred days, suggesting a characteristic timescale for the depletion or removal of obscuring gas.

Keywords: Accretion, Black hole physics, Supermassive black holes, Tidal disruption, X-ray transient sources
New Analytic Solutions for Galaxy Evolution. II. Wind Recycling, Galactic Fountains, and Late-type Galaxies. We generalize the analytic solutions presented in Pantoni et al. by including a simple yet effective description of wind recycling and galactic fountains, with the aim of self-consistently investigating the spatially averaged time evolution of the gas, stellar, metal, and dust content in disk-dominated late-type galaxies (LTGs). Our analytic solutions, when supplemented with specific prescriptions for parameter setting and with halo accretion rates from N-body simulations, can be exploited to reproduce the main statistical relationships followed by local LTGs; these involve, as a function of the stellar mass, the star formation efficiency, the gas mass fraction, the gas/stellar metallicity, the dust mass, the star formation rate, the specific angular momentum, and the overall mass/metal budget. Our analytic solutions allow us to easily disentangle the diverse role of the main physical processes ruling galaxy formation in LTGs; in particular, we highlight the crucial relevance of wind recycling and galactic fountains in efficiently refurnishing the gas mass, extending the star formation timescale, and boosting the metal enrichment in gas and stars. All in all, our analytic solutions constitute a transparent, handy, and fast tool that can provide a basis for improving the (sub-grid) physical recipes presently implemented in more sophisticated semi-analytic models and numerical simulations, and can serve as a benchmark for interpreting and forecasting current and future spatially averaged observations of local and higher redshift LTGs.

Keywords: Galaxy fountains, Galaxy formation, Late-type galaxies, Galaxy evolution
Carbonaceous Chondrites and the Condensation of Elements from the Solar Nebula. Common features of all carbonaceous chondrite groups are invariant refractory element ratios, depletions of moderately volatile elements as a function of their condensation temperature (TC), and strongly depleted highly volatile element concentrations independent of TC. The depletion of volatile elements with respect to the bulk solar system composition requires a separation of gas from solids in the solar nebula. Several models have been proposed to explain the decoupling of gas and solids, but not all are compatible with astrophysical, chemical, and petrologic constraints. Here existing physical models are integrated with measured element concentrations, measured and modeled physical properties of protoplanetary disks, and planetary-scale nucleosynthetic and stable isotope variations to establish a conceptual model for the condensation and accretion of elements into planetesimals. In this model, the chemical composition of chondrites is established by element condensation in a cooling solar nebula that changed its surface density as a function of time and temperature. The model predicts peak temperatures at the condensation sites of about 1400 K that consequently decreased due to a diminishing heat source originating from viscous heating and radiation, accompanied by continuous removal of gas from the nebula surface by photoevaporation. The coupled evolution of condensing solids from a nebula of diminishing surface density resulted in a pattern of decreasing moderately volatile abundances with decreasing TC. The reduction of nebula opacity due to the chondrule-forming process significantly increased nebula cooling rates and led to the near-chondritic relative abundances of highly volatile elements observed in carbonaceous chondrites.

Keywords: Isotope shifts, Carbonaceous chondrites, Solar system, Solar system formation