Sazuna/UAT_keywords huggingface dataset:
An Evenly Spaced LSST Cadence for Rapidly Variable Stars. Stars exhibit a bewildering variety of rapidly variable behaviors ranging from explosive magnetic flares to stochastically changing accretion to periodic pulsations or rotation. The principal Rubin Observatory Legacy Survey of Space and Time (LSST) surveys will have cadences too sparse and irregular to capture many of these phenomena. We propose here an LSST microsurvey to observe a single Galactic field, rich in unobscured stars, in a continuous sequence of 30 s exposures for one long winter night in a single photometric band. The result will be a unique data set of ~1 million regularly spaced stellar light curves. The light curves will constitute a comprehensive collection of late-type stellar flaring, but also other classes like short-period binary systems and cataclysmic variables, young stellar objects, and ultrashort-period exoplanets. An unknown variety of anomalous solar system, Galactic, and extragalactic variables and transients may also be present. A powerful array of statistical procedures can be applied to individual light curves from the long-standing fields of time series analysis, signal processing, and econometrics. Dozens of "features" describing the variability can be extracted and the ensemble of light curves can be subject to advanced machine-learning clustering procedures. This will give a unique, authoritative, objective taxonomy of the rapidly variable sky derived from identically cadenced light curves. This microsurvey is best performed early in the Rubin Observatory program, and the results can inform the wider community on the best approaches to variable star identification and classification from the sparse, irregular cadences that dominate the planned surveys.

Keywords: Light curve classification , Time series analysis, Time domain astronomy, Variable stars
Deuterated Polycyclic Aromatic Hydrocarbons in the Interstellar Medium: The Aliphatic C-D Band Strengths. Deuterium (D) was exclusively generated in the Big Bang, and the standard Big Bang nucleosynthesis (BBN) model predicts a primordial abundance of D/H ≈ 26 parts per million (ppm). As the Galaxy evolves, D/H gradually decreases because of astration. The Galactic chemical evolution (GCE) model predicts a present-day abundance of D/H ≳ 20 ppm. However, observations of the local interstellar medium have revealed that the gas-phase interstellar D/H varies considerably from one region to another and has a median abundance of D/H ≈ 13 ppm, substantially lower than predicted from the BBN and GCE models. It has been suggested that the missing D atoms of D/H ≈ 7 ppm could have been locked up in deuterated polycyclic aromatic hydrocarbon (PAH) molecules. However, we have previously demonstrated that PAHs with aromatic C-D units are insufficient to account for the missing D. Here we explore if PAHs with aliphatic C-D units could be a reservoir of D. We perform quantum chemical computations of the vibrational spectra of superdeuterated PAHs (in which one D and one H share one C atom) and PAHs to which a D-substituted methyl group is attached, and derive the band strengths of the aliphatic C-D stretch (A 4.65). By applying the computationally derived A 4.65 to the observed aliphatic C-D emission at ~4.6-4.8 μm, we find that PAHs with aliphatic C-D units could have tied up a substantial amount of D/H and marginally account for the missing D. The possible routes for generating PAHs with aliphatic C-D units are also discussed.

Keywords: Interstellar molecules, Interstellar line emission, Polycyclic aromatic hydrocarbons, Astrochemistry, Line intensities
Rubin Observatory's Survey Strategy Performance for Tidal Disruption Events. Tidal disruption events (TDEs) are rare transients, which are considered as promising tools for probing supermassive black holes in quiescent galaxies. The majority of the ≈60 known TDEs have been discovered with time-domain surveys in the last two decades. Currently, ≈10 TDEs are discovered per year, and this number will increase with the Legacy Survey of Space and Time (LSST) at the Rubin Observatory. This work evaluates LSST survey strategies in view of their performance in identifying TDEs. We assume that TDEs can be identified photometrically based on their colors, particularly in the u band, and will be scientifically useful if we can detect the light-curve peak to derive physical quantities. We define the requirements for the Rubin light curves that are needed to achieve this (detections prepeak, postpeak, and in different bands to measure color). We then inject model light curves into the Operations Simulator and calculate the fractions of TDEs passing our requirements for several strategies. We find that under the baseline strategy, ≈1.5% of simulated TDEs fulfill our detection criteria, while this number increases when more time is devoted to u-band observations. An ideal observing strategy for the photometric identification of TDEs would have longer u-band exposures, which should not come at the expense of fewer u-band visits. A filter distribution weighted toward more observing time in bluer bands, intranight visits in different filters, and strategies with frequent sampling leading to higher-quality light curves are preferred. We find that these strategies benefiting TDE science do not impact significantly other science cases.

Keywords: Surveys, Tidal disruption, Black holes
Completeness of the NASA/IPAC Extragalactic Database (NED) Local Volume Sample. We introduce the NASA/IPAC Extragalactic Database (NED) Local Volume Sample (NED-LVS), a subset of ~1.9 million objects with distances out to 1000 Mpc. We use UV and IR fluxes available in NED from all-sky surveys to derive physical properties, and estimate the completeness relative to the expected local luminosity density. The completeness relative to near-IR luminosities (which traces a galaxy's stellar mass) is roughly 100% at D &lt; 30 Mpc and remains moderate (70%) out to 300 Mpc. For brighter galaxies (≳L *), NED-LVS is ~100% complete out to ~400 Mpc. When compared to other local Universe samples (GLADE and HECATE), all three are ~100% complete below 30 Mpc. At distances beyond ~80 Mpc, NED-LVS is more complete than both GLADE and HECATE by ~10%-20%. NED-LVS is the underlying sample for the NED gravitational-wave follow-up service (NED-GWF), which provides prioritized lists of host candidates for GW events within minutes of alerts issued by the LIGO-Virgo-KAGRA collaboration. We test the prioritization of galaxies in the volume of GW170817 by three physical properties, where we find that both stellar mass and inverse specific star formation rate place the correct host galaxy in the top 10. In addition, NED-LVS can be used for a wide variety of other astrophysical studies: galaxy evolution, star formation, large-scale structure, galaxy environments, and more. The data in NED are updated regularly, and NED-LVS will be updated concurrently. Consequently, NED-LVS will continue to provide an increasingly complete sample of galaxies for a multitude of astrophysical research areas for years to come.

Keywords: Surveys, Catalogs, Astronomy databases, Galaxies
The JWST Resolved Stellar Populations Early Release Science Program. II. Survey Overview. We present the JWST Resolved Stellar Populations Early Release Science (ERS) program. We obtained 27.5 hr of NIRCam and NIRISS imaging of three targets in the Local Group (Milky Way globular cluster M92, ultrafaint dwarf galaxy Draco II, and star-forming dwarf galaxy WLM), which span factors of ~105 in luminosity, ~104 in distance, and ~105 in surface brightness. We describe the survey strategy, scientific and technical goals, implementation details, present select NIRCam color-magnitude diagrams (CMDs), and validate the NIRCam exposure time calculator (ETC). Our CMDs are among the deepest in existence for each class of target. They touch the theoretical hydrogen-burning limit in M92 (&lt;0.08 M ⊙; M F090W ~ +13.6), include the lowest-mass stars observed outside the Milky Way in Draco II (0.09 M ⊙; M F090W ~ +12.1), and reach ~1.5 mag below the oldest main-sequence turnoff in WLM (M F090W ~ +4.6). The PARSEC stellar models provide a good qualitative match to the NIRCam CMDs, though they are ~0.05 mag too blue compared to M92 F090W - F150W data. Our CMDs show detector-dependent color offsets ranging from ~0.02 mag in F090W - F150W to ~0.1 mag in F277W - F444W; these appear to be due to differences in the zero-point calibrations among the detectors. The NIRCam ETC (v2.0) matches the signal-to-noise ratios based on photon noise in uncrowded fields, but the ETC may not be accurate in more crowded fields, similar to what is known for the Hubble Space Telescope. We release the point-source photometry package DOLPHOT, optimized for NIRCam and NIRISS, for the community.

Keywords: Stellar photometry, Local Group, Stellar populations, James Webb Space Telescope, Hertzsprung Russell diagram
A Catalog of New Slowly Pulsating B-type Stars. This paper reports the discovery of new slowly pulsating B-type stars. Based on the photometric, spectral, and astrometric data of the TESS, LAMOST, and Gaia surveys, we have found 286 new slowly pulsating B-type (SPB) stars and 21 candidates. Among these, 20 are Be stars or candidates with emission-line profiles. It is shown that these SPB stars have luminosities between 40 and 2850 L ⊙ and effective temperatures ranging from 10,000 to 21,000 K. Their pulsation periods are from 0.14 to 6.5 days with amplitude ranges of 0.2-20 mmag in the TESS band. It is indicated that these targets follow the distribution of the SPB stars in the period-luminosity and the period-temperature diagrams. Their positions on the H-R diagram reveal that most of these pulsators are distributed in the instability region of SPB stars, in the main-sequence evolutionary stage, and with mass ranges of 2.5-7 M ⊙. However, there are some targets beyond the red edge of the theoretical instability region, which should be caused by the rapid rotation reducing the measured effective temperature. The discovery of these new SPB stars increases the total number by over 60%, which are significant samples for further investigating the structure and evolution of intermediate-mass and even massive stars by asteroseismology.

Keywords: Massive stars, Pulsating variable stars
The Chandra Source Catalog Normal Galaxy Sample. We present the extensive and well-characterized Chandra X-ray Galaxy Catalog (CGC) of 8547 galaxy candidates in the redshift range z ~ 0.04-0.7, optical luminosity 1010-1011 Lr ⊙, and X-ray luminosity (0.5-7 keV) L X = 2 × 1040-2 × 1043 erg s-1. We estimate a ~5% false-match fraction and contamination by quasi-stellar objects (QSOs). The CGC was extracted from the Chandra Source Catalog version 2 (CSC2) by cross-correlating with optical and IR all-sky survey data, including the Sloan Digital Sky Survey, Pan-STARRS, DESI Legacy, and Wide-field Infrared Survey Explorer (WISE). Our selection makes use of two main criteria that we have tested on the subsample with optical spectroscopical identification. (1) A joint selection based on X-ray luminosity (L X) and X-ray-to-optical flux ratio (F XO), which recovers 63% of the spectroscopically classified galaxies with a small contamination fraction (7%), which is a significant improvement over methods using L X or F XO alone (&lt;50% recovery). (2) A joint W1-W2 (W12) WISE color and L X selection that proves effective in excluding QSOs and improves our selection by recovering 72% of the spectroscopically classified galaxies and reducing the contamination fraction (4%). Of the CGC, 24% was selected by means of optical spectroscopy; 30% on the basis of L X, F XO, and W12; and 46% by using either the L X-F XO or the L X-W12 selection criteria. We have individually examined the data for galaxies with z &lt; 0.1, which may include more than one CSC2 X-ray source, leading to the exclusion of 110 local galaxies. Our catalog also includes near-IR and UV data and galaxy morphological types.

Keywords: Galaxies
Linear Mode Decomposition in Magnetohydrodynamics Revisited. Small-amplitude fluctuations in the magnetized solar wind are measured typically by a single spacecraft. In the magnetohydrodynamics (MHD) description, fluctuations are typically expressed in terms of the fundamental modes admitted by the system. An important question is how to resolve an observed set of fluctuations, typically plasma moments such as the density, velocity, pressure, and magnetic field fluctuations, into their constituent fundamental MHD modal components. Despite its importance in understanding the basic elements of waves and turbulence in the solar wind, this problem has not yet been fully resolved. Here, we introduce a new method that identifies between wave modes and advected structures such as magnetic islands or entropy modes and computes the phase information associated with the eligible MHD modes. The mode-decomposition method developed here identifies the admissible modes in an MHD plasma from a set of plasma and magnetic field fluctuations measured by a single spacecraft at a specific frequency and an inferred wavenumber k  m . We present data from three typical intervals measured by the Wind and Solar Orbiter spacecraft at ~1 au and show how the new method identifies both propagating (wave) and nonpropagating (structures) modes, including entropy and magnetic island modes. This allows us to identify and characterize the separate MHD modes in an observed plasma parcel and to derive wavenumber spectra of entropic density, fast and slow magnetosonic, Alfvénic, and magnetic island fluctuations for the first time. These results help identify the fundamental building blocks of turbulence in the magnetized solar wind.

Keywords: Solar wind
Magellan/M2FS and MMT/Hectochelle Spectroscopy of Dwarf Galaxies and Faint Star Clusters within the Galactic Halo. We present spectroscopic data for 16,369 stellar targets within and/or toward 38 dwarf spheroidal galaxies and faint star clusters within the Milky Way halo environment. All spectra come from observations with the multiobject, fiber-fed echelle spectrographs M2FS at the Magellan/Clay telescope or Hectochelle at the MMT, reaching a typical limiting magnitude G ≲ 21. Data products include processed spectra from all observations and catalogs listing estimates-derived from template model fitting-of line-of-sight velocity (median uncertainty 1.4 km s-1) effective temperature (255 K), (base-10 logarithm of) surface gravity (0.59 dex in cgs units), [Fe/H] (0.4 dex) and [Mg/Fe] (0.27 dex) abundance ratios. The sample contains multiepoch measurements for 3720 sources, with up to 15 epochs per source, enabling studies of intrinsic spectroscopic variability. The sample contains 6087 likely red giant stars (based on surface gravity), and 4492 likely members (based on line-of-sight velocity and Gaia-measured proper motion) of the target systems. The number of member stars per individual target system ranges from a few, for the faintest systems, to ~850 for the most luminous. For most systems, our new samples extend over wider fields than have previously been observed; of the likely members in our samples, 820 lie beyond 2 times the projected half-light radius of their host system, and 42 lie beyond 5 R half. * This paper presents data gathered with the Magellan Telescopes at Las Campanas Observatory, Chile, and the MMT Observatory, a joint facility of the Smithsonian Institution, and the University of Arizona.

Keywords: Milky Way dark matter halo, Galaxy dark matter halos, Dark matter distribution, Dwarf galaxies, Chemical abundances, Milky Way stellar halo, Dwarf spheroidal galaxies, Spectroscopy, Radial velocity, Metallicity, Dark matter
Long-term X-Ray Outburst in the TeV-detected Blazar Mrk 501 in 2021-2022: Further Clues for the Emission and Unstable Processes. This paper presents the results of a detailed X-ray timing and spectral analysis of Mrk 501, which are based mainly on the Swift data obtained during 2021 February-2022 December. The source showed strongly enhanced X-ray activity, characterized by a long-term increase in the baseline 0.3-10 keV flux level superimposed by shorter-term flares on timescales of a few weeks to about 2 months. During some time intervals, Mrk 501 was the brightest blazar in the X-ray sky and, moreover, showed an intense intraday variability, which was sometimes detected within the exposures lasting a few hundred seconds. These instances were characterized by fractional variability amplitudes of 4%-18% and were mostly observed during short-term X-ray flares. The source exhibited extreme spectral properties with dominance of the spectral curvature, frequent occurrence of hard photon indices in the 0.3-10 keV and 0.3-300 GeV bands, and the peak of a synchrotron spectral energy distribution in the hard X-ray range. These properties demonstrate the importance of relativistic magnetic reconnection, first-order Fermi mechanism within the magnetic field of different confinement efficiencies, stochastic acceleration, and hadronic processes. The X-ray and γ-ray fluxes showed a log-normal distribution, which hints at the imprint of accretion disk instabilities on the blazar jet, as well as the possible presence of hadronic cascades and random fluctuations in the particle acceleration rate. The optical-UV and γ-ray variabilities showed a weak or absent correlation with the X-ray flaring activity, which is not consistent with simple leptonic models and requires more complex particle acceleration, emission, and variability scenarios.

Keywords: BL Lacertae objects
Catalog of the Galactic Population of X-Ray Pulsars in High-mass X-Ray Binary Systems. A catalog of the Galactic population of X-ray pulsars in high-mass X-ray binary (HMXB) systems is presented. It contains information about 82 confirmed sources: 18 persistent and 64 transient pulsars. Their basic parameters include spin period, spin evolution with global and local spin-up/spin-down and duration, orbital period, X-ray luminosity, magnetic field strength measured by cyclotron line analysis, distance, spectral and luminosity class, and observable parameters of massive companions, which are shown in the tables provided, with corresponding references. Candidates of HMXB pulsars are also listed for further careful consideration.

Keywords: Neutron stars, Accretion, High energy astrophysics, High mass x-ray binary stars, Pulsars
Electron-impact Excitation of Pt I-III: The Importance of Metastables and Collision Processes in Neutron Star Merger and Laboratory Plasmas. The detection of a gravitational-wave signal and subsequent electromagnetic transient from a neutron star merger in 2017 is consistent with expectations of neutron star mergers as an r-process element production site. Within the first few days post-merger, the kilonova spectra are consistent with a blackbody illuminating a mix of heavy, r-process elements. With increasing time, the kilonova transitions to the non-LTE regime where the level populations and ionization balance are determined by both collisional and photoprocesses. Detailed cross section data for electron-impact processes involving the relevant species are often not available. In such circumstances, it is reasonable to use approximate methods as baseline data for use in spectral modeling, and it is useful to evaluate the accuracy of such methods against more sophisticated collision calculations when possible. We describe new calculations of the electron-impact excitation cross sections of Pt I-III using the DARC R-matrix codes. Using collisional-radiative models, we show that, at plasma conditions expected in kilonovae, the expressions of van Regemorter and Axelrod are insufficient for producing electron-impact excitation data for complex, heavy species such as the low charge states of Pt. Through comparisons with data generated with the relativistic distorted wave approach, as implemented in the Flexible Atomic Code, we show the distorted wave method produces cross section data that, when incorporated into spectral models, predicts strong spectral feature distributions similar in intensity to those from models built on data computed with the R-matrix approach for the considered ions and plasma conditions.

Keywords: Collision physics, Laboratory astrophysics, Electron impact excitation
Characterizing the Emission Region Properties of Blazars. Studies and constraints on the emission region are crucial to the blazar radiation mechanism. Yet previous works have mainly focused on individual sources. In this work, we make use of the largest and the latest spectral energy distribution fitting results in the literature to statistically study the blazar emission region properties in the framework of a one-zone leptonic model. Our results reveal: (1) that flat-spectrum radio quasars (FSRQs) show lower electron energy (γ p ≲ 1.6 × 103) than BL Lacertae objects (BL Lacs) and tend to have a stronger magnetic field (B) and smaller electron-to-magnetic energy ratio (U e/U B) than BL Lacs; (2) we find that the electromagnetic equipartition would rather happen in the jets of BL Lacs than happen in the jets of FSRQs; (3) there are 682 blazars with a magnetic field weaker than the critical value for generating the Kelvin-Helmholtz instability, thus one-third of the blazars in our sample are able to produce this instability; and (4) the distance (d em) between the emission region and the central black hole is on the scale of ~0.1 pc, so the location of the emission region may be evenly distributed inside and outside the broad-line region.

Keywords: Jets, BL Lacertae objects, Blazars, Flat-spectrum radio quasars, Magnetic fields
SILVERRUSH. XIII. A Catalog of 20,567 Lyα Emitters at z = 2-7 Identified in the Full-depth Data of the Subaru/HSC-SSP and CHORUS Surveys. We present 20,567 Lyα emitters (LAEs) at z = 2.2 - 7.3 that are photometrically identified by the SILVERRUSH program in a large survey area up to 25 deg2 with deep images of five broadband filters (grizy) and seven narrowband filters targeting Lyα lines at z = 2.2, 3.3, 4.9, 5.7, 6.6, 7.0, and 7.3 taken by the Hyper Suprime-Cam Subaru Strategic Program and the Cosmic HydrOgen Reionization Unveiled with Subaru survey. We select secure &gt;5σ sources showing narrowband color excesses via Lyα break screening, taking into account the spatial inhomogeneity of limiting magnitudes. After removing spurious sources by careful masking and visual inspection of coadded and multiepoch images obtained over the 7 yr of the surveys, we construct LAE samples consisting of 6995, 4641, 726, 6124, 2058, 18, and 5 LAEs at z = 2.2, 3.3, 4.9, 5.7, 6.6, 7.0, and 7.3, respectively, although the z = 7.3 candidates are tentative. Our LAE catalogs contain 289 spectroscopically confirmed LAEs at the expected redshifts from previous work. We demonstrate that the number counts of our LAEs are consistent with previous studies with similar LAE selection criteria. The LAE catalogs will be made public on our project webpage with detailed descriptions of the content and ancillary information about the masks and limiting magnitudes.

Keywords: Galaxy formation, Galaxy evolution, Lyman-alpha galaxies, High-redshift galaxies, Catalogs