Sazuna/UAT_keywords huggingface dataset:
Catalog of Solar Failed Eruptions and Other Dynamic Features Registered by SDO/AIA. In this paper we present our attempt to constrain the first catalog of solar failed eruptions. We used our automatic algorithm that is able to search for dynamic features in the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) database. We ran the algorithm on the entire SDO/AIA 171 Å data set. For the time interval from 2010 May 20 to 2019 May 20 we found 12,192 dynamic events. The dynamic events were classified in three groups. Apart from failed eruptions (1214) we obtained a large group of successful eruptions (2064) and other dynamic events (8914). The automatic algorithm enabled us to collect several observational characteristics, which are provided in files that may be downloaded from the catalog web page. In this paper we present the methodology of catalog preparation and preliminary results of the statistical analysis of observational characteristics obtained by the automatic algorithm.

Keywords: Solar prominences, Solar extreme ultraviolet emission, Solar active regions, Solar filaments, Solar corona, Solar activity
A Catalog of RV Variable Star Candidates from LAMOST. Radial velocity (RV) variable stars are important in astrophysics. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic survey has provided ∼6.5 million stellar spectra in its Data Release 4 (DR4). During the survey ∼4.7 million unique sources were targeted and ∼1 million stars observed repeatedly. The probabilities of stars being RV variables are estimated by comparing the observed RV variations with simulated ones. We build a catalog of 80,702 RV variable candidates with probability greater than 0.60 by analyzing the multi-epoch sources covered by LAMOST DR4. Simulations and cross-identifications show that the purity of the catalog is higher than 80%. The catalog consists of 77% binary systems and 7% pulsating stars as well as 16% pollution by single stars. 3138 RV variables are classified through cross-identifications with published results in literatures. By using the 3138 sources common in both LAMOST and a collection of published RV variable catalogs, we are able to analyze LAMOST's RV variable detection rate. The efficiency of the method adopted in this work relies not only on the sampling frequency of observations but also periods and amplitudes of RV variables. With the progress of LAMOST, Gaia, and other surveys, more and more RV variables will be confirmed and classified. This catalog is valuable for other large-scale surveys, especially for RV variable searches. The catalog will be released according to the LAMOST Data Policy via http://dr4.lamost.org.

Keywords: Binary stars, Pulsating variable stars, Surveys, Astrostatistics, Stellar astronomy, Extrinsic variable stars, Variable stars, Spectroscopy, Radial velocity, Star counts, Catalogs, Intrinsic variable stars
The Galactic Plane Infrared Polarization Survey (GPIPS): Data Release 4. The Galactic Plane Infrared Polarization Survey (GPIPS) seeks to characterize the magnetic field in the dusty Galactic disk using near-infrared stellar polarimetry. All GPIPS observations were completed using the 1.83 m Perkins telescope and Mimir instrument. GPIPS observations surveyed 76 deg2 of the northern Galactic plane, from Galactic longitudes 18°-56° and latitudes -1° to +1°, in the H band (1.6 μm). Surveyed stars span 7th-16th mag, resulting in nearly 10 million stars with measured linear polarizations. Of these stars, ones with mH &lt; 12.5 mag and polarization percentage uncertainties under 2% were judged to be high quality and number over one million. GPIPS data reveal plane-of-sky magnetic field orientations for numerous interstellar clouds for AV values to ∼30 mag. The average sky separation of stars with mH &lt; 12.5 mag is about 30″, or about 60 per Planck polarization resolution element. Matching to Gaia DR2 showed the brightest GPIPS stars are red giants with distances in the 0.6-7.5 kpc range. Polarization orientations are mostly parallel to the Galactic disk, with some zones showing significant orientation departures. Changes in orientations are stronger as a function of Galactic longitude than of latitude. Considered at 10' angular scales, directions that show the greatest polarization fractions and narrowest polarization position angle distributions are confined to about 10 large, coherent structures that are not correlated with star-forming clouds. The GPIPS polarimetric and photometric data products (Data Release 4 catalogs and images) are publicly available for over 13 million stars.

Keywords: Surveys, Polarimetry, Interstellar magnetic fields, Galaxy disks, Starlight polarization, Milky Way disk, Magnetic fields
Forecasting Chemical Abundance Precision for Extragalactic Stellar Archaeology. Increasingly powerful and multiplexed spectroscopic facilities promise detailed chemical abundance patterns for millions of resolved stars in galaxies beyond the Milky Way (MW). Here, we employ the Cramér-Rao lower bound (CRLB) to forecast the precision to which stellar abundances for metal-poor, low-mass stars outside the MW can be measured for 41 current (e.g., Keck, MMT, the Very Large Telescope, and the Dark Energy Spectroscopic Instrument) and planned (e.g., the Maunakea Spectroscopic Explorer, the James Webb Space Telescope (JWST), and Extremely Large Telescopes (ELTs)) spectrograph configurations. We show that moderate-resolution (R ≲ 5000) spectroscopy at blue-optical wavelengths (λ ≲ 4500 Å) (i) enables the recovery of two to four times as many elements as red-optical spectroscopy (5000 ≲ λ ≲ 10000 Å) at similar or higher resolutions (R ∼ 10,000) and (ii) can constrain the abundances of several neutron-capture elements to ≲0.3 dex. We further show that high-resolution (R ≳ 20,000), low signal-to-noise ratio (∼10 pixel-1) spectra contain rich abundance information when modeled with full spectral fitting techniques. We demonstrate that JWST/NIRSpec and ELTs can recover (i) ∼10 and 30 elements, respectively, for metal-poor red giants throughout the Local Group and (ii) [Fe/H] and [α/Fe] for resolved stars in galaxies out to several Mpc with modest integration times. We show that select literature abundances are within a factor of ∼2 (or better) of our CRLBs. We suggest that, like exposure time calculators, CRLBs should be used when planning stellar spectroscopic observations. We include an open-source Python package, Chem-I-Calc, that allows users to compute CRLBs for spectrographs of their choosing.

Keywords: Local Group, Fundamental parameters of stars, Stellar abundances, Astronomy data analysis, Red giant stars, Spectroscopy
ECoPANN: A Framework for Estimating Cosmological Parameters Using Artificial Neural Networks. In this work, we present a new method to estimate cosmological parameters accurately based on the artificial neural network (ANN), and a code called ECoPANN (Estimating Cosmological Parameters with ANN) is developed to achieve parameter inference. We test the ANN method by estimating the basic parameters of the concordance cosmological model using the simulated temperature power spectrum of the cosmic microwave background (CMB). The results show that the ANN performs excellently on best-fit values and errors of parameters, as well as correlations between parameters when compared with that of the Markov Chain Monte Carlo (MCMC) method. Besides, for a well-trained ANN model, it is capable of estimating parameters for multiple experiments that have different precisions, which can greatly reduce the consumption of time and computing resources for parameter inference. Furthermore, we extend the ANN to a multibranch network to achieve a joint constraint on parameters. We test the multibranch network using the simulated temperature and polarization power spectra of the CMB, Type Ia supernovae, and baryon acoustic oscillations and almost obtain the same results as the MCMC method. Therefore, we propose that the ANN can provide an alternative way to accurately and quickly estimate cosmological parameters, and ECoPANN can be applied to the research of cosmology and even other broader scientific fields.

Keywords: Neural networks, Cosmological parameters, Observational cosmology, Astronomy data analysis, Computational methods
Formation of Complex Organic Molecules in Cold Interstellar Environments through Nondiffusive Grain-surface and Ice-mantle Chemistry. A prevailing theory for the interstellar production of complex organic molecules (COMs) involves formation on warm dust-grain surfaces, via the diffusion and reaction of radicals produced through grain-surface photodissociation of stable molecules. However, some gas-phase O-bearing COMs, notably acetaldehyde (CH3CHO), methyl formate (CH3OCHO), and dimethyl ether (CH3OCH3), are now observed at very low temperatures, challenging the warm scenario. Here, we introduce a selection of new nondiffusive mechanisms into an astrochemical model to account for the failure of the standard diffusive picture and to provide a more generalized scenario of COM formation on interstellar grains. New generic rate formulations are provided for cases where (i) radicals are formed by reactions occurring close to another reactant, producing an immediate follow-on reaction; (ii) radicals are formed in an excited state, allowing them to overcome activation barriers to react with nearby stable molecules; and (iii) radicals are formed through photodissociation close to a reaction partner, followed by immediate reaction. Each process occurs without thermal diffusion of large radicals. The new mechanisms significantly enhance cold COM abundances, successfully reproducing key observational results for prestellar core L1544. H abstraction from grain-surface COMs, followed by recombination, plays a crucial role in amplifying chemical desorption into the gas phase. The ultraviolet-induced chemistry produces significant COM abundances in the bulk ices, which are retained on the grains and may persist to later stages. O2 is also formed strongly in the mantle though photolysis, suggesting cometary O2 could indeed be interstellar.

Keywords: Interstellar dust processes, Star formation, Astrochemistry
The Molecular Clouds Associated with the H II Regions/Candidates between L = 207°7 and L = 211°7. Using the PMO-13.7 m millimeter telescope at Delingha in China, we have conducted a large-scale simultaneous survey of 12CO, 13CO, and C18O J = 1 - 0 emission toward the sky region centered at l = 209°7, b = -2°25 with a coverage of 4°0 × 4°5. The majority of the emission in the region comes from the clouds with velocities lying in the range from -3 to 55 km s-1, at kinematic distances from 0.5 to 7.0 kpc. The molecular clouds in the region are concentrated into three velocity ranges. The molecular clouds associated with the 10 H II regions/candidates are identified and their physical properties are presented. Massive stars are found within Sh2-280, Sh2-282, Sh2-283, and BFS54, and we suggest them to be the candidate excitation sources of the H II regions. The distributions of the excitation temperature and line width with the projected distance from the center of H II region/candidate suggest that the majority of the 10 H II regions/candidates and their associated molecular gas are three-dimensional structures, rather than two-dimensional structures.

Keywords: Molecular spectroscopy, H II regions, Molecular clouds
Magnetic Field Dropouts at Near-Sun Switchback Boundaries: A Superposed Epoch Analysis. During Parker Solar Probe's first close encounter with the Sun in early 2018 November, a large number of impulsive rotations in the magnetic field were detected within 50 Rs; these also occurred in association with short-lived impulsive solar wind bursts in speed. These impulsive features are now called "switchback" events. We examined a set of these switchbacks where the boundary transition into and out of the switchback was abrupt, with fast B rotations and simultaneous solar wind speed changes occurring on timescales of less than ∼10 s; these thus appear as step function-like changes in the radial component of B and V. Our objective was to search for any diamagnetic effects that might occur especially if the boundaries are associated with quick changes in density (i.e., a steep spatial density gradient at the switchback boundary). We identified 25 switchback entries where the radial component of B, Br, quickly transitioned from large negative to positive values and Vr simultaneously abruptly increased (i.e., step-up transitions) and 28 switchback exits where Br quickly transitioned from large positive to negative values and Vr simultaneously abruptly decreased (i.e., step-down transitions). We then performed a superposed epoch analysis on each of these sets of events. We found these fast-transitioning events typically had a clear and distinct decrease in the magnetic field magnitude by 7%-8% detected exactly at the boundary. The presence of the $| B| $ dropout suggests there is a diamagnetic current present at the boundary.

Keywords: The Sun, Solar wind, Solar physics
Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. I. Precise Distances, Masses, Ages, and 3D Velocities of ∼140,000 Red Clump Stars. We present a sample of ∼140,000 primary red clump (RC) stars of spectral signal-to-noise ratios higher than 20 from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Galactic spectroscopic surveys, selected based on their positions in the metallicity-dependent effective temperature-surface gravity and color-metallicity diagrams, supervised by high-quality Kepler asteroseismology data. The stellar masses and ages of those stars are further determined from the LAMOST spectra, using the kernel principal component analysis method and are trained with thousands of RCs in the LAMOST-Kepler fields with accurate asteroseismic mass measurements. The purity and completeness of our primary RC sample are generally higher than 80%. For the mass and age, a variety of tests show typical uncertainties of 15% and 30%, respectively. Using over 10,000 primary RCs with accurate distance measurements from the parallaxes of Gaia Data Release 2 (DR2), we recalibrate the Ks absolute magnitudes of primary RCs by, for the first time, considering both the metallicity and age dependencies. With the the new calibration, distances are derived for all the primary RCs, with a typical uncertainty of 5-10%, which is even better than the values yielded by the Gaia parallax measurements for stars beyond 3-4 kpc. The sample covers a significant volume of the Galactic disk of 4 ≤ R ≤ 16 kpc, $| Z| \leqslant 5\,\mathrm{kpc}$ , and -20 ≤ φ ≤ 50°. Stellar atmospheric parameters, line-of-sight velocities, and elemental abundances derived from the LAMOST spectra and proper motions of Gaia DR2 are also provided for the sample stars. Finally, the selection function of the sample is carefully evaluated in the color-magnitude plane for different sky areas. The sample is publicly available at 10.5281/zenodo.3875974.

Keywords: Stellar ages, Red giant clump, Galaxy structure, Distance indicators, Milky Way disk, Galaxy abundances, Stellar masses
The R-Process Alliance: Fourth Data Release from the Search for R-process-enhanced Stars in the Galactic Halo. This compilation is the fourth data release from the R-Process Alliance (RPA) search for r-process-enhanced stars and the second release based on "snapshot" high-resolution (R ∼ 30,000) spectra collected with the du Pont 2.5 m Telescope. In this data release, we propose a new delineation between the r-I and r-II stellar classes at $[\mathrm{Eu}/\mathrm{Fe}]=+0.7$ , instead of the empirically chosen $[\mathrm{Eu}/\mathrm{Fe}]=+1.0$ level previously in use, based on statistical tests of the complete set of RPA data released to date. We also statistically justify the minimum level of [Eu/Fe] for definition of the r-I stars, [Eu/Fe] &gt; +0.3. Redefining the separation between r-I and r-II stars will aid in the analysis of the possible progenitors of these two classes of stars and determine whether these signatures arise from separate astrophysical sources at all. Applying this redefinition to previous RPA data, the number of identified r-II and r-I stars changes to 51 and 121, respectively, from the initial set of data releases published thus far. In this data release, we identify 21 new r-II, 111 new r-I (plus 3 re-identified), and 7 new (plus 1 re-identified) limited-r stars out of a total of 232 target stars, resulting in a total sample of 72 new r-II stars, 232 new r-I stars, and 42 new limited-r stars identified by the RPA to date. * This paper includes data gathered with the 2.5 m du Pont telescope located at Las Campanas Observatory, Chile.

Keywords: Nucleosynthesis, Stellar abundances, R-process, Population II stars, Metallicity, Stellar atmospheres
A Catalog of Short Period Spectroscopic and Eclipsing Binaries Identified from the LAMOST and PTF Surveys. Binaries play key roles in determining stellar parameters and exploring stellar evolution models. We build a catalog of 88 eclipsing binaries with spectroscopic information, taking advantage of observations from both the Large Sky Area Multi-Object fiber Spectroscopic Telescope and the Palomar Transient Factory surveys. A software pipeline is constructed to identify binary candidates by examining their light curves. The orbital periods of binaries are derived from the Lomb-Scargle method. The key distinguishing features of eclipsing binaries are recognized by a new filter, Flat Test. We classify the eclipsing binaries by applying a Fourier analysis on the light curves. Among all the binary stars, 13 binaries are identified as eclipsing binaries for the first time. The catalog contains the following information: the position, primary eclipsing magnitude and time, eclipsing depth, the number of photometry and radial velocity observations, largest radial velocity difference, binary type, the effective temperature of the observable star Teff, and surface gravity of the observable star log g. The false-positive probability is calculated by using both a Monte Carlo simulation and real data from the Sloan Digital Sky Survey Stripe 82 Standard Catalog. The binaries in the catalog are mostly with a period of less than one day. The period distribution shows a 0.22 day cutoff, which is consistent with the low probability of an eclipsing binary rotating with such a period.

Keywords: Binary stars, Close binary stars, Spectroscopic binary stars, Detached binary stars, Eclipsing binary stars, Contact binary stars
The Multi-INstrument Burst ARchive (MINBAR). We present the largest sample of type I (thermonuclear) X-ray bursts yet assembled, comprising 7083 bursts from 85 bursting sources. The sample is drawn from observations with Xenon-filled proportional counters on the long-duration satellites RXTE, BeppoSAX, and International Gamma-Ray Astrophysics Laboratory between 1996 February 8 and 2012 May 3. The burst sources were drawn from a comprehensive catalog of 115 burst sources, assembled from earlier catalogs and the literature. We carried out a consistent analysis for each burst light curve (normalized to the relative instrumental effective area) and provide measurements of rise time, peak intensity, burst timescale, and fluence. For bursts observed with the RXTE/PCA and BeppoSAX/Wide Field Camera we also provide time-resolved spectroscopy, including estimates of bolometric peak flux and fluence, and spectral parameters at the peak of the burst. For 950 bursts observed with the PCA from sources with previously detected burst oscillations, we include an analysis of the high time resolution data, providing information on the detectability and amplitude of the oscillations, as well as where in the burst they are found. We also present analysis of 118,848 observations of the burst sources within the sample time frame. We extracted 3-25 keV X-ray spectra from most observations, and (for observations meeting our signal-to-noise criterion) we provide measurements of the flux, spectral colors, and, for selected sources, the position on the color-color diagram, for the best-fit spectral model. We present a description of the sample, a summary of the science investigations completed to date, and suggestions for further studies.

Keywords: Neutron stars, X-ray bursts, X-ray transient sources, Nuclear astrophysics, Astrophysical explosive burning, Catalogs, X-ray bursters
Molecular Cloud Cores with a High Deuterium Fraction: Nobeyama Single-pointing Survey. We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments (λ Orionis, Orion A, Orion B, the Galactic plane, and high latitudes) to identify dense cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores in eight molecular lines at 76-94 GHz using the Nobeyama 45 m telescope. We find that early-type molecules (e.g., CCS) have low detection rates and that late-type molecules (e.g., N2H+ and c-C3H2) and deuterated molecules (e.g., N2D+ and DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction (D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between the D/H pair of lines for distant cores (&gt;1 kpc). For λ Orionis, Orion A, and Orion B located at similar distances, D/H is not significantly different, suggesting that there is no systematic difference in the observed chemical properties among these three regions. We identify at least eight high-D/H cores in the Orion region and two at high latitudes, which are most likely to be close to the onset of star formation. There is no clear evidence of the evolutionary change in turbulence during the starless phase, suggesting that the dissipation of turbulence is not a major mechanism for the beginning of star formation as judged from observations with a beam size of 0.04 pc.

Keywords: Interstellar molecules, Earth's clouds, Star formation, Astrochemistry
Classifying Single Stars and Spectroscopic Binaries Using Optical Stellar Templates. Stellar spectral classification is a fundamental tool of modern astronomy, providing insight into physical characteristics such as effective temperature, surface gravity, and metallicity. Accurate and fast spectral typing is an integral need for large all-sky spectroscopic surveys like the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. Here, we present the next version of PyHammer, a stellar spectral classification software that uses optical spectral templates and spectral line index measurements. PyHammer v2.0 extends the classification power to include dwarf carbon stars, DA white dwarf stars, and also double-lined spectroscopic binaries (SB2). This release also includes a new empirical library of luminosity-normalized spectra that can be used to flux calibrate observed spectra or to create synthetic SB2 spectra. We have generated physically reasonable SB2 combinations as templates, adding the ability to spectrally type SB2s to PyHammer. We test classification success rates on SB2 spectra, generated from the SDSS, across a wide range of spectral types and signal-to-noise ratios. Within the defined range of pairings described, more than 95% of SB2s are correctly classified.

Keywords: Astronomy software, White dwarf stars, Carbon stars, Spectroscopic binary stars, Stellar classification