Sazuna/UAT_keywords huggingface dataset:
Orbits and Masses of Binaries from Speckle Interferometry at SOAR. We present results from Speckle inteferometric observations of 15 visual binaries and one double-line spectroscopic binary, carried out with the HRCam Speckle camera of the SOAR 4.1 m telescope. These systems were observed as a part of an on-going survey to characterize the binary population in the solar vicinity, out to a distance of 250 pc. We obtained orbital elements and mass sums for our sample of visual binaries. The orbits were computed using a Markov Chain Monte Carlo algorithm that delivers maximum likelihood estimates of the parameters, as well as posterior probability density functions that allow us to evaluate their uncertainty. Their periods cover a range from 5 yr to more than 500 yr; and their spectral types go from early A to mid M, implying total system masses from slightly more than 4M⊙ down to 0.2M⊙. They are located at distances between approximately 12 and 200 pc, mostly at low Galactic latitude. For the double-line spectroscopic binary YSC8, we present the first combined astrometric/radial-velocity orbit resulting from a self-consistent fit, leading to individual component masses of 0.897 ± 0.027 M⊙ and 0.857 ± 0.026 M⊙; and an orbital parallax of 26.61 ± 0.29 mas, which compares very well with the Gaia DR2 trigonometric parallax (26.55 ± 0.27 mas). In combination with published photometry and trigonometric parallaxes, we place our objects on an H-R diagram and discuss their evolutionary status. We also present a thorough analysis of the precision and consistency of the photometry available for them. * Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministrio da Cincia, Tecnologia, e Inovao (MCTI) da Repblica Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

Keywords: CCD photometry, Stellar luminosities, Sky surveys, Stellar masses, Interferometric binary stars, Radial velocity, Spectroscopic binary stars, Astrometry, Speckle interferometry, Hertzsprung Russell diagram, Visual binary stars, Stellar evolutionary tracks
A Decade of Radial-velocity Monitoring of Vega and New Limits on the Presence of Planets. We present an analysis of 1524 spectra of Vega spanning 10 yr, in which we search for periodic radial-velocity variations. A signal with a periodicity of 0.676 day and a semi-amplitude of ∼10 m s-1 is consistent with the rotation period measured over much shorter time spans by previous spectroscopic and spectropolarimetric studies, confirming the presence of surface features on this A0 star. The activity signal appears to evolve on long timescales, which may indicate the presence of failed fossil magnetic fields on Vega. TESS data reveal Vega's photometric rotational modulation for the first time, with a total amplitude of only 10 ppm. A comparison of the spectroscopic and photometric amplitudes suggests that the surface features may be dominated by bright plages rather than dark spots. For the shortest orbital periods, transit and radial-velocity injection recovery tests exclude the presence of transiting planets larger than 2 R⊕ and most non-transiting giant planets. At long periods, we combine our radial velocities with direct imaging from the literature to produce detection limits for Vegan planets and brown dwarfs out to distances of 15 au. Finally, we detect a candidate radial-velocity signal with a period of 2.43 days and a semi-amplitude of 6 m s-1. If caused by an orbiting companion, its minimum mass would be ∼20 M⊕; because of Vega's pole-on orientation, this would correspond to a Jovian planet if the orbit is aligned with the stellar spin. We discuss the prospects for confirmation of this candidate planet.

Keywords: Exoplanets, Radial velocity, Stellar magnetic fields, Stellar activity, Exoplanet astronomy, Photometry, Circumstellar disks, Exoplanet detection methods
GLEAM: Galaxy Line Emission &amp; Absorption Modeling. We present Galaxy Line Emission &amp; Absorption Modeling (GLEAM), a Python tool for fitting Gaussian models to emission and absorption lines in large samples of 1D extragalactic spectra. GLEAM is tailored to work well in batch mode without much human interaction. With GLEAM, users can uniformly process a variety of spectra, including galaxies and active galactic nuclei, in a wide range of instrument setups and signal-to-noise regimes. GLEAM also takes advantage of multiprocessing capabilities to process spectra in parallel. With the goal of enabling reproducible workflows for its users, GLEAM employs a small number of input files, including a central, user-friendly configuration in which fitting constraints can be defined for groups of spectra and overrides can be specified for edge cases. For each spectrum, GLEAM produces a table containing measurements and error bars for the detected spectral lines and continuum and upper limits for nondetections. For visual inspection and publishing, GLEAM can also produce plots of the data with fitted lines overlaid. In the present paper, we describe GLEAM's main features, the necessary inputs, expected outputs, and some example applications, including thorough tests on a large sample of optical/infrared multi-object spectroscopic observations and integral field spectroscopic data. GLEAM is developed as an open-source project hosted at https://github.com/multiwavelength/gleam and welcomes community contributions.

Keywords: Open source software, Astronomy software, Astronomy data analysis, Astronomical techniques, Active galactic nuclei, Spectroscopy, Galaxies
WIYN Open Cluster Study. LXXXV. Li in NGC 2243: Implications for Stellar and Galactic Evolution. High-dispersion spectra in the Li λ6708 region have been obtained and analyzed in the old, metal-deficient cluster NGC 2243. From Hydra spectra for 29 astrometric and radial velocity members, we derive rotational velocities, as well as [Fe/H], [Ca/H], [Si/H], and [Ni/H] based on 17, 1, 1, and 3 lines, respectively. Using ROBOSPECT, an automatic equivalent width measurement program, we derive [Fe/H] = -0.54 ± 0.11 (MAD), for an internal precision for the cluster [Fe/H] below 0.03 dex. Given the more restricted line set, comparable values for [Ca/H], [Si/H], and [Ni/H] are -0.48 ± 0.19, -0.44 ± 0.11, and -0.61 ± 0.06, respectively. With E(B - V) = 0.055, appropriate isochrones imply (m - M) = 13.2 ± 0.1 and an age of 3.6 ± 0.2 Gyr. Using available VLT spectra and published Li abundances, we construct an Li sample of over 100 stars extending from the tip of the giant branch to 0.5 mag below the Li dip. The Li dip is well populated and, when combined with results for NGC 6819 and Hyades/Praesepe, implies a mass/metallicity slope of 0.4 M☉/dex for the high-mass edge of the Li dip. The A(Li) distribution among giants reflects the degree of Li variation among the turnoff stars above the Li dip, itself a function of stellar mass and metallicity and strongly anticorrelated with a vrot distribution that dramatically narrows with age. Potential implications of these patterns for the interpretation of Li among dwarf and giant field populations, especially selection biases tied to age and metallicity, are discussed.

Keywords: Open star clusters, Stellar abundances
The Binary INformation from Open Clusters Using SEDs (BINOCS) Project: Reliable Photometric Mass Determinations of Binary Star Systems in Clusters. We introduce a new binary detection technique, Binary INformation from Open Clusters using SEDs (BINOCS), which we show is able to determine reliable stellar multiplicity and masses over a much larger mass range than current approaches. This new technique determines accurate component masses of binary and single systems of the open clusters' main sequence by comparing observed magnitudes from multiple photometric filters to synthetic star spectral energy distributions (SEDs), allowing us to systematically probe the binary population for low-mass stars in clusters for eight well-studied open clusters. We provide new deep, infrared photometric catalogs (1.2-8.0 μm) for the key open clusters NGC 1960 (M36), NGC 2099 (M37), NGC 2420, and NGC 2682 (M67), using observations from NOAO/NEWFIRM and Spitzer/IRAC. Using these deep multiwavelength catalogs, the BINOCS method is applied to these clusters to determine accurate component masses for unresolved cluster binaries. We explore binary fractions as a function of cluster age, Galactic location, and metallicity.

Keywords: Open star clusters, Binary stars, Infrared photometry
Precise Transit and Radial-velocity Characterization of a Resonant Pair: The Warm Jupiter TOI-216c and Eccentric Warm Neptune TOI-216b. TOI-216 hosts a pair of warm, large exoplanets discovered by the TESS mission. These planets were found to be in or near the 2:1 resonance, and both of them exhibit transit timing variations (TTVs). Precise characterization of the planets' masses and radii, orbital properties, and resonant behavior can test theories for the origins of planets orbiting close to their stars. Previous characterization of the system using the first six sectors of TESS data suffered from a degeneracy between planet mass and orbital eccentricity. Radial-velocity measurements using HARPS, FEROS, and the Planet Finder Spectrograph break that degeneracy, and an expanded TTV baseline from TESS and an ongoing ground-based transit observing campaign increase the precision of the mass and eccentricity measurements. We determine that TOI-216c is a warm Jupiter, TOI-216b is an eccentric warm Neptune, and that they librate in 2:1 resonance with a moderate libration amplitude of ${60}_{-2}^{+2}$ deg, a small but significant free eccentricity of ${0.0222}_{-0.0003}^{+0.0005}$ for TOI-216b, and a small but significant mutual inclination of 1°2-3°9 (95% confidence interval). The libration amplitude, free eccentricity, and mutual inclination imply a disturbance of TOI-216b before or after resonance capture, perhaps by an undetected third planet.

Keywords: Exoplanet astronomy, Radial velocity, Transit timing variation method, Exoplanet dynamics
TIC 168789840: A Sextuply Eclipsing Sextuple Star System. We report the discovery of a sextuply eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0"42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ∼2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. Markov Chain Monte Carlo (MCMC) analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are "triplets," as each binary is quite similar to the others in terms of mass, radius, and Teff. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries.

Keywords: Eclipsing binary stars, Multiple stars, Transit photometry, Astronomy data analysis
Commissioning the H I Observing Mode of the Beam Former for the Cryogenically Cooled Focal L-band Array for the GBT (FLAG). We present the results of commissioning observations for a new digital beam-forming back end for the Focal plane L-band Array for the Robert C. Byrd Green Bank Telescope (FLAG), a cryogenically cooled Phased Array Feed (PAF) with the lowest measured Tsys/η of any PAF outfitted on a radio telescope to date. We describe the custom software used to apply beam-forming weights to the raw element covariances to create research-quality spectral-line images for the new fine-channel mode, study the stability of the beam weights over time, characterize FLAG's sensitivity over a frequency range of 150 MHz, and compare the measured noise properties and observed distribution of neutral hydrogen emission from several extragalactic and Galactic sources with data obtained with the current single-pixel L-band receiver. These commissioning runs establish FLAG as the preeminent PAF receiver currently available for spectral-line observations on the world's major radio telescopes.

Keywords: Observational astronomy, Neutral hydrogen clouds, H I line emission, Astronomical instrumentation, Radio astronomy
Speckle Observations of TESS Exoplanet Host Stars: Understanding the Binary Exoplanet Host Star Orbital Period Distribution. We present high-resolution speckle interferometric imaging observations of TESS exoplanet host stars using the NN-EXPLORE Exoplanet and Stellar Speckle Imager instrument at the 3.5 m WIYN telescope. Eight TESS objects of interest that were originally discovered by Kepler were previously observed using the Differential Speckle Survey Instrument. Speckle observations of 186 TESS stars were carried out, and 45 (24%) likely bound companions were detected. This is approximately the number of companions we would expect to observe given the established 46% binarity rate in exoplanet host stars. For the detected binaries, the distribution of stellar mass ratio is consistent with that of the standard Raghavan distribution and may show a decrease in high-q systems as the binary separation increases. The distribution of binary orbital periods, however, is not consistent with the standard Ragahavan model, and our observations support the premise that exoplanet-hosting stars with binary companions have, in general, wider orbital separations than field binaries. We find that exoplanet-hosting binary star systems show a distribution peaking near 100 au, higher than the 40-50 au peak that is observed for field binaries. This fact led to earlier suggestions that planet formation is suppressed in close binaries.

Keywords: Exoplanets
Fundamental Parameters of the Eclipsing Binary DD CMa and Evidence for Mass Exchange. We present a detailed photometric and spectroscopic analysis of DD CMa, based on published survey photometry and new spectroscopic data. We find an improved orbital period of Po = 2.0084530(6) days. Our spectra reveal Hβ and Hα absorptions with weak emission shoulders, and we also find a color excess in the Wide-field Infrared Survey Explorer multiband photometry, interpreted as signatures of circumstellar matter. We model the V-band orbital light curve derived from the ASAS and ASAS-SN surveys, assuming a semidetached configuration and using the mass ratio and temperature of the hotter star derived from our spectroscopic analysis. Our model indicates that the system consists of a B2.5 dwarf and a B9 giant of radii 3.2 and 3.7 R⊙, respectively, orbiting in a circular orbit of radius 6.75 R⊙. We also found Mc = 1.7 ± 0.1 M⊙, Tc = 11,350 ± 100 K, and Mh = 6.4 ± 0.1 M⊙, Th = 20,000 ± 500 K, for the cooler and hotter star, respectively. We find broad single emission peaks in Hα and Hβ after subtracting the synthetic stellar spectra. Our results are consistent with mass exchange between the stars and suggest the existence of a stream of gas being accreted onto the early B-type star.

Keywords: Close binary stars, Fundamental parameters of stars, Stellar activity, Circumstellar matter, Eclipsing binary stars
Unlocking Starlight Subtraction in Full-data-rate Exoplanet Imaging by Efficiently Updating Karhunen-Loève Eigenimages. Starlight subtraction algorithms based on the method of Karhunen-Loève eigenimages have proved invaluable to exoplanet direct imaging. However, they scale poorly in runtime when paired with differential imaging techniques. In such observations, reference frames and frames from which starlight is to be subtracted are drawn from the same set of data, requiring a new subset of references (and eigenimages) for each frame processed to avoid self-subtraction of the signal of interest. The data rates of extreme adaptive optics instruments are such that the only way to make this computationally feasible has been to downsample the data. We develop a technique that updates a precomputed singular value decomposition of the full data set to remove frames (i.e., a "downdate") without a full recomputation, yielding the modified eigenimages. This not only enables analysis of much larger data volumes in the same amount of time, but also exhibits near-linear scaling in runtime as the number of observations increases. We apply this technique to archival data and investigate its scaling behavior for very large numbers of frames N. The resulting algorithm provides speed improvements of 2.6× (for 200 eigenimages at N = 300) to 140× (at N = 104) with the advantage only increasing as N grows. This algorithm has allowed us to substantially accelerate Karhunen-Loève image projection (KLIP) even for modest N, and will let us quickly explore how KLIP parameters affect exoplanet characterization in large-N data sets.

Keywords: Exoplanets, Astronomy data analysis, Direct imaging, Exoplanet detection methods, Astronomy data reduction
The APOGEE Library of Infrared SSP Templates (A-LIST): High-resolution Simple Stellar Population Spectral Models in the H Band. Integrated light spectroscopy from galaxies can be used to study the stellar populations that cannot be resolved into individual stars. This analysis relies on stellar population synthesis (SPS) techniques to study the formation history and structure of galaxies. However, the spectral templates available for SPS are limited, especially in the near-infrared (near-IR). We present A-LIST (APOGEE Library of Infrared SSP Templates), a new set of high-resolution, near-IR SSP spectral templates spanning a wide range of ages (2-12 Gyr), metallicities ( - 2.2 &lt; [M/H] &lt; + 0.4) and α abundances ( - 0.2 &lt; [α/M] &lt; + 0.4). This set of SSP templates is the highest resolution (R ∼ 22, 500) available in the near-IR, and the first such based on an empirical stellar library. Our models are generated using spectra of ∼300,000 stars spread across the Milky Way, with a wide range of metallicities and abundances, from the APOGEE survey. We show that our model spectra provide accurate fits to M31 globular cluster spectra taken with APOGEE, with best-fit metallicities agreeing with those of previous estimates to within ∼0.1 dex. We also compare these model spectra to lower-resolution E-MILES models and demonstrate that we recover the ages of these models to within ∼1.5 Gyr. This library is available in https://github.com/aishashok/ALIST-library.

Keywords: Stellar evolutionary models, Galaxy stellar content, Galaxy chemical evolution, Stellar evolution
On the Classification and Feature Relevance of Multiband Light Curves. With an expected torrent of data from the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), the need for automated identification of noisy and sparse light curves will increase drastically. In this paper, we performed classification of multiband astronomical light curves from the Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC) data set via boosted neural nets, boosted decision trees, and a voted classifier for 14 astronomical categories. In order to deal with noisy features, we used wavelet decomposition together with feature selection. We also performed a feature ranking method using a neural network. Our method may be considered an alternative to random forests, which is known to favor features with more categories as relevant. We also investigated the class importance with neural nets using a one-versus-all approach which reduces the multiclass problem to a binary class problem.

Keywords: Light curve classification , Astronomy data analysis, Wavelet analysis
The White Dwarfs of the Old, Solar-metallicity Open Star Cluster Messier 67: Properties and Progenitors. The old, solar-metallicity open cluster Messier 67 has long been considered a lynchpin in the study and understanding of the structure and evolution of solar-type stars. The same is arguably true for stellar remnants; the white dwarf population of M67 provides crucial observational data for understanding and interpreting white dwarf populations and evolution. In this work, we determine the white dwarf masses and derive their progenitor star masses using high signal-to-noise spectroscopy of warm (≳10,000 K) DA white dwarfs in the cluster. From this, we are able to derive each white dwarf's position on the initial-final mass relation (IFMR), with an average MWD = 0.60 ± 0.01 M⊙ and progenitor mass Mi = 1.52 ± 0.04 M⊙. These values are fully consistent with recently published linear and piecewise linear fits to the semiempirical IFMR and provide a crucial, precise anchor point for the IFMR for solar-metallicity, low-mass stars. The mean mass of M67 white dwarfs is also consistent with the sharp narrow peak in the local field white dwarf mass distribution, indicating that a majority of recently formed field white dwarfs come from stars with progenitor masses of ≈1.5 M⊙. Our results enable more precise modeling of the Galactic star formation rate encoded in the field white dwarf mass distribution. * Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Keywords: Open star clusters, White dwarf stars, Stellar evolution
The Swan: Data-driven Inference of Stellar Surface Gravities for Cool Stars from Photometric Light Curves. Stellar light curves are well known to encode physical stellar properties. Precise, automated, and computationally inexpensive methods to derive physical parameters from light curves are needed to cope with the large influx of these data from space-based missions such as Kepler and TESS. Here we present a new methodology that we call "The Swan," a fast, generalizable, and effective approach for deriving stellar surface gravity ( $\mathrm{log}g$ ) for main-sequence, subgiant, and red giant stars from Kepler light curves using local linear regression on the full frequency content of Kepler long-cadence power spectra. With this inexpensive data-driven approach, we recover $\mathrm{log}g$ to a precision of ∼0.02 dex for 13,822 stars with seismic $\mathrm{log}g$ values between 0.2 and 4.4 dex and ∼0.11 dex for 4646 stars with Gaia-derived $\mathrm{log}g$ values between 2.3 and 4.6 dex. We further develop a signal-to-noise metric and find that granulation is difficult to detect in many cool main-sequence stars (Teff ≲ 5500 K), in particular K dwarfs. By combining our $\mathrm{log}g$ measurements with Gaia radii, we derive empirical masses for 4646 subgiant and main-sequence stars with a median precision of ∼7%. Finally, we demonstrate that our method can be used to recover $\mathrm{log}g$ to a similar mean absolute deviation precision for a TESS baseline of 27 days. Our methodology can be readily applied to photometric time series observations to infer stellar surface gravities to high precision across evolutionary states.

Keywords: Astronomy data modeling, Light curves, Stellar astronomy, Time domain astronomy, Photometry, Linear regression, Stellar oscillations, Asteroseismology, Stellar granulation