Sazuna/UAT_keywords huggingface dataset:
A Census of the TW Hya Association with Gaia. I have used high-precision photometry and astrometry from the third data release of Gaia to perform a survey for members of the TW Hya association (TWA). I have identified candidate members that appear to share similar kinematics and ages with bona fide members compiled by Gagné et al. (2017), and I have assessed their membership using radial velocities and spectroscopic diagnostics of age from various sources. My new catalog of adopted members contains 67 Gaia sources in 55 systems. The histogram of spectral types for TWA peaks near M5 (∼0.15 M ⊙), resembling the distributions measured for other nearby young associations. The UVW velocities of its members indicate that the association is expanding. The rate of expansion corresponds to an age of   Myr. In a Gaia color─magnitude diagram, the members of TWA exhibit well-defined sequences of single stars and unresolved binary stars. The combined sequence of low-mass stars in TWA is indicative of an age of   Myr when compared to the sequence for Upper Centaurus Lupus/Lower Centaurus Crux, for which an age of 20 Myr is assumed. Based on these expansion and isochronal ages, I have adopted an age of 10 ± 2 Myr for TWA. Finally, I have used mid-infrared photometry from the Wide-field Infrared Survey Explorer to check for excess emission from circumstellar disks among the TWA members. Fourteen members have detected disks, all of which have been reported in previous studies. The fraction of members at ≤ M6 (≳0.1 M ⊙) that have full, transitional, or evolved disks is 10/52 =  . That value is similar to the fraction previously measured for the Upper Sco association, which is roughly coeval with TWA. * Based on observations made with the Gaia mission, the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer, Gemini Observatory, and European Southern Observatory telescopes at La Silla and Paranal Observatories.

Keywords: Initial mass function, Star formation, Low mass stars, Protoplanetary disks, Circumstellar disks, Stellar associations
OrbitN: A Symplectic Integrator for Planetary Systems Dominated by a Central Mass-Insight into Long-term Solar System Chaos. Reliable studies of the long-term dynamics of planetary systems require numerical integrators that are accurate and fast. The challenge is often formidable because the chaotic nature of many systems requires relative numerical error bounds at or close to machine precision (~10-16, double-precision arithmetic); otherwise, numerical chaos may dominate over physical chaos. Currently, the speed/accuracy demands are usually only met by symplectic integrators. For example, the most up-to-date long-term astronomical solutions for the solar system in the past (widely used in, e.g., astrochronology and high-precision geological dating) have been obtained using symplectic integrators. However, the source codes of these integrators are unavailable. Here I present the symplectic integrator orbitN (lean version 1.0) with the primary goal of generating accurate and reproducible long-term orbital solutions for near-Keplerian planetary systems (here the solar system) with a dominant mass M 0. Among other features, orbitN-1.0 includes M 0's quadrupole moment, a lunar contribution, and post-Newtonian corrections (1PN) due to M 0 (fast symplectic implementation). To reduce numerical round-off errors, Kahan compensated summation was implemented. I use orbitN to provide insight into the effect of various processes on the long-term chaos in the solar system. Notably, 1PN corrections have the opposite effect on chaoticity/stability on a 100 Myr versus Gyr timescale. For the current application, orbitN is about as fast as or faster (factor 1.15-2.6) than comparable integrators, depending on hardware. 1 1 The orbitN source code (C) is available at http://github.com/rezeebe/orbitN.

Keywords: Celestial mechanics, Solar system, N-body simulations, Orbital theory
Quantifying Uncertainties on the Tip of the Red Giant Branch Method. We present an extensive grid of numerical simulations quantifying the uncertainties in measurements of the tip of the red giant branch (TRGB). These simulations incorporate a luminosity function composed of 2 mag of red giant branch (RGB) stars leading up to the tip, with asymptotic giant branch (AGB) stars contributing exclusively to the luminosity function for at least a magnitude above the RGB tip. We quantify the sensitivity of the TRGB detection and measurement to three important error sources: (1) the sample size of stars near the tip, (2) the photometric measurement uncertainties at the tip, and (3) the degree of self-crowding of the RGB population. The self-crowding creates a population of supra-TRGB stars due to the blending of one or more RGB stars just below the tip. This last population is ultimately difficult, although still possible, to disentangle from true AGB stars. In the analysis given here, the precepts and general methodology as used in the Chicago-Carnegie Hubble Program (CCHP) have been followed. However, in the appendix, we introduce and test a set of new tip detection kernels, which internally incorporate self-consistent smoothing. These are generalizations of the two-step model used by the CCHP (smoothing followed by Sobel-filter tip detection), where the new kernels are based on successive binomial-coefficient approximations to the derivative-of-a-Gaussian edge-detector, as is commonly used in modern digital image processing.

Keywords: Red giant stars, Distance indicators
A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions. Wide-field and deep DECam multiband photometry, combined with HST data for the core of the Galactic globular cluster NGC 2808, allowed us to study the distribution of various stellar subpopulations and stars in different evolutionary phases out to the cluster tidal radius. We used the C  ugi  = (u - g) - (g - i) index to identify three chemically distinct subpopulations along the red giant branch and compared their spatial distributions. The most light-element-enriched subpopulation (P3) is more centrally concentrated; however, it shows a more extended distribution in the external regions of the cluster compared to the primordial (P1) and intermediate (P2) composition populations. Furthermore, the P3 subpopulation centroid is off-center relative to those of the P1 and P2 groups. We also analyzed the spatial distribution of horizontal branch stars and found that the relative fraction of red horizontal branch stars increases for radial distances larger than ≈1.'5, while that of the blue and hotter stars decreases. These new observations, combined with literature spectroscopic measurements, suggest that the red horizontal branch stars are the progeny of all the stellar subpopulations in NGC 2808, i.e., primordial and light-element enhanced, while the blue stars are possibly the result of a combination of the "hot-flasher" and the "helium-enhanced" scenarios. A similar distribution of different red giant branch subpopulations and horizontal branch stars was also found for the most massive Galactic globular cluster, ω Cen, based on combined DECam and HST data, which suggests that the two may share a similar origin.

Keywords: Globular star clusters
Magnetic Field Measurements of Low-mass Stars from High-resolution Near-infrared IGRINS Spectra. We present average magnetic field measurements derived from high-resolution near-infrared IGRINS spectra of a carefully selected sample of 28 M dwarfs. All 28 have reported magnetic field strengths in the literature. The main goal of this work is to investigate the accuracy, precision, and limitations of magnetic field measurements from IGRINS spectra. This investigation is critical to validating the robustness of our methods before we apply them to over 500 IGRINS-observed M dwarfs in the next paper of the series. We used the Zeeman broadening and Zeeman intensification methods to measure average magnetic fields. Our measurements are all consistent with the previous measurements to within ±1 kG, with an average offset of -0.17 kG for the broadening method and +0.19 kG for the intensification method. We find that the detection limit of IGRINS is ~0.9 kG with the Zeeman broadening method, in accordance with the instrumental broadening limit of the spectrograph. With the Zeeman intensification method, we are able to detect down to ~0.7 kG with a signal-to-noise ratio of 150 or greater. We find an advantage of using the intensification method over the broadening method, which is the ability to reliably measure the magnetic field strengths of stars that are cooler than 3100 K where the spectrum becomes dominated by molecular lines. Therefore, the intensification method is crucial to study stellar magnetism of late-M and brown dwarfs.

Keywords: M dwarf stars, Stellar astronomy, Late-type dwarf stars, Low mass stars
Disk or Companion: Characterizing Excess Infrared Flux in Seven White Dwarf Systems with Near-infrared Spectroscopy. Excess infrared flux from white dwarf stars is likely to arise from a dusty debris disk or a cool companion. In this work, we present near-infrared spectroscopic observations with Keck/MOSFIRE, Gemini/GNIRS, and Gemini/Flamingos-2 of seven white dwarfs with infrared excesses identified in previous studies. We confirmed the presence of dust disks around four white dwarfs (Gaia J0611-6931, Gaia J0006+2858, Gaia J2100+2122, and WD 0145+234) as well as two new white dwarf-brown dwarf pairs (Gaia J0052+4505 and Gaia J0603+4518). In three of the dust disk systems, we detected for the first time near-infrared metal emissions (Mg I, Si I, and possibly Fe I) from a gaseous component of the disk. We developed a new Markov Chain Monte Carlo framework to constrain the geometric properties of each dust disk. In three systems, the dust disk and the gas disk appear to coincide spatially. For the two brown dwarf-white dwarf pairs, we identified broad molecular absorption features typically seen in L dwarfs. The origin of the infrared excess around Gaia J0723+6301 remains a mystery. Our study underlines how near-infrared spectroscopy can be used to determine sources of infrared excess around white dwarfs, which has now been detected photometrically in hundreds of systems.

Keywords: Brown dwarfs, Infrared spectroscopy, White dwarf stars, Infrared excess, Debris disks
A Noninteracting Galactic Black Hole Candidate in a Binary System with a Main-sequence Star. We describe the discovery of a solar neighborhood (d = 468 pc) binary system with a main-sequence sunlike star and a massive noninteracting black hole candidate. The spectral energy distribution of the visible star is described by a single stellar model. We derive stellar parameters from a high signal-to-noise Magellan/MIKE spectrum, classifying the star as a main-sequence star with T eff = 5972 K, $\mathrm{log}g=4.54$ , and M = 0.91 M ⊙. The spectrum shows no indication of a second luminous component. To determine the spectroscopic orbit of the binary, we measured the radial velocities of this system with the Automated Planet Finder, Magellan, and Keck over four months. We show that the velocity data are consistent with the Gaia astrometric orbit and provide independent evidence for a massive dark companion. From a combined fit of our spectroscopic data and the astrometry, we derive a companion mass of ${11.39}_{-1.31}^{+1.51}$ M ⊙. We conclude that this binary system harbors a massive black hole on an eccentric (e = 0.46 ± 0.02), 185.4 ± 0.1 day orbit. These conclusions are independent of El-Badry et al., who recently reported the discovery of the same system. A joint fit to all available data yields a comparable period solution but a lower companion mass of ${9.32}_{-0.21}^{+0.22}{M}_{\odot }$ . Radial velocity fits to all available data produce a unimodal solution for the period that is not possible with either data set alone. The combination of both data sets yields the most accurate orbit currently available.

Keywords: High resolution spectroscopy, Binary stars, Black holes, Astrometric binary stars, Gaia, Milky Way Galaxy
TOI-4010: A System of Three Large Short-period Planets with a Massive Long-period Companion. We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by the Transiting Exoplanet Survey Satellite in Sectors 24, 25, 52, and 58. We confirm these planets with the High Accuracy Radial velocity Planet Searcher for the Northern Hemisphere radial velocity observations and measure their masses with 8-12% precision. TOI-4010 b is a sub-Neptune (P = 1.3 days, ${R}_{p}={3.02}_{-0.08}^{+0.08}\,{R}_{\oplus }$ , ${M}_{p}={11.00}_{-1.27}^{+1.29}\,{M}_{\oplus }$ ) in the hot-Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c (P = 5.4 days, ${R}_{p}={5.93}_{-0.12}^{+0.11}\,{R}_{\oplus }$ , ${M}_{p}={20.31}_{-2.11}^{+2.13}\,{M}_{\oplus }$ ) and TOI-4010 d (P = 14.7 days, ${R}_{p}={6.18}_{-0.14}^{+0.15}\,{R}_{\oplus }$ , ${M}_{p}={38.15}_{-3.22}^{+3.27}\,{M}_{\oplus }$ ) are similarly sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit (P ~ 762 days and e ~ 0.26 based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.

Keywords: Exoplanet dynamics, Exoplanets, Hot Neptunes, Exoplanet systems, Transit photometry
Radio-optical Reference Catalog, Version 1. The fundamental celestial reference frame (CRF) is based on two catalogs of astrometric positions: the third realization of the International Celestial Reference Frame (ICRF3), and the much larger Gaia CRF, built from the third data release (DR3). The objects in common between these two catalogs are mostly distant AGNs and quasars that are both sufficiently optically bright for Gaia and radio loud for the VLBI. This limited collection of reference objects is crucially important for the mutual alignment of the two CRFs and the maintenance of all of the other frames and coordinate systems branching from the ICRF. In this paper, we show that the three components of ICRF3 (S/X, K, and X/Ka band catalogs) have significantly different sky-correlated vector fields of position offsets with respect to Gaia DR3. When iteratively expanded in the vector spherical harmonics up to degree 4 on a carefully vetted set of common sources, each of these components includes several statistically significant terms. The median sky-correlated offsets from the Gaia positions are found to be 56 μas for the S/X, 100 μas for the K, and 324 μas for the X/Ka catalogs. The weighted mean vector field is subtracted from the Gaia reference positions, while the deviations from that field are added to each of the ICRF3 components. The corrected positions from each of the four input catalogs are combined into a single weighted mean catalog, which we propose to be the current most accurate realization of an inertial radio-optical CRF.

Keywords: Astronomical coordinate systems, Very long baseline interferometry, Radio loud quasars, Astrometry, Gaia
VaTEST. II. Statistical Validation of 11 TESS-detected Exoplanets Orbiting K-type Stars. NASA's Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission designed to find transiting exoplanets orbiting nearby bright stars. It has identified more than 329 transiting exoplanets, and almost 6000 candidates remain unvalidated. In this manuscript, we discuss the findings from the ongoing Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project, which aims to validate new exoplanets for further characterization. We validated 11 new exoplanets by examining the light curves of 24 candidates using the LATTE and TESS-Plot tools and computing the false-positive probabilities using the statistical validation tool TRICERATOPS. These include planets suitable for atmospheric characterization using transmission spectroscopy (TOI-2194b), emission spectroscopy (TOI-3082b and TOI-5704b) and for both transmission and emission spectroscopy (TOI-672b, TOI-1694b, and TOI-2443b). Our validated planets have one super-Earth (TOI-2194b) orbiting a bright (V = 8.42 mag), metal-poor ([Fe/H] = -0.3720 ± 0.1) star, and one short-period Neptune-like planet (TOI-5704) in the hot-Neptune desert. In total, we validated one super-Earth, seven sub-Neptunes, one Neptune-like, and two sub-Saturn or super-Neptune-like exoplanets. Additionally, we identify five likely planet candidates (TOI-323, TOI-1180, TOI-2200, TOI-2408, and TOI-3913), which can be further studied to establish their planetary nature.

Keywords: Exoplanet astronomy, Exoplanet detection methods, Exoplanet systems
The Hazardous km-sized NEOs of the Next Thousands of Years. The catalog of km-sized near-Earth objects (NEOs) is nearly complete. Typical impact monitoring analyses search for possible impacts over the next 100 yr and none of the km-sized objects represent an impact threat over that time interval. Assessing the impact risk over longer timescales is a challenge since orbital uncertainties grow. To overcome this limitation we analyze the evolution of the minimum orbit intersection distance (MOID), which bounds the closest possible encounters between the asteroid and the Earth. The evolution of the MOID highlights NEOs that are in the vicinity of the Earth for longer periods of time, and we propose a method to estimate the probability of a deep Earth encounter during these periods. This metric is used to rank the km-sized catalog in terms of their long-term impact hazard to identify targets of potential interest for additional observation and exploration.

Keywords: Astrodynamics, Near-Earth objects, Asteroids, Asteroid dynamics, Close encounters
Mid-to-late M Dwarfs Lack Jupiter Analogs. Cold Jovian planets play an important role in sculpting the dynamical environment in which inner terrestrial planets form. The core accretion model predicts that giant planets cannot form around low-mass M dwarfs, although this idea has been challenged by recent planet discoveries. Here, we investigate the occurrence rate of giant planets around low-mass (0.1-0.3 M ☉) M dwarfs. We monitor a volume-complete, inactive sample of 200 such stars located within 15 pc, collecting four high-resolution spectra of each M dwarf over six years and performing intensive follow-up monitoring of two candidate radial velocity variables. We use TRES on the 1.5 m telescope at the Fred Lawrence Whipple Observatory and CHIRON on the Cerro Tololo Inter-American Observatory 1.5 m telescope for our primary campaign, and MAROON-X on Gemini-North for high-precision follow up. We place a 95% confidence upper limit of 1.5% (68% confidence limit of 0.57%) on the occurrence of M P sin i &gt; 1 M J giant planets out to the water snow line and provide additional constraints on the giant planet population as a function of M P sin i and period. Beyond the snow line (100 K &lt; T eq &lt; 150 K), we place 95% confidence upper limits of 1.5%, 1.7%, and 4.4% (68% confidence limits of 0.58%, 0.66%, and 1.7%) for 3 M J &lt; M P sin i &lt; 10 M J, 0.8 M J &lt; M P sin i &lt; 3 M J, and 0.3 M J &lt; M P sin i &lt; 0.8 M J giant planets, respectively; i.e., Jupiter analogs are rare around low-mass M dwarfs. In contrast, surveys of Sun-like stars have found that their giant planets are most common at these Jupiter-like instellations.

Keywords: M dwarf stars, High resolution spectroscopy, Surveys, Radial velocity, Extrasolar gaseous giant planets
On the Origins of Extreme Velocity Stars as Revealed by Large-scale Galactic Surveys. We assemble a large sample of 12,784 high-velocity stars with total velocity V GSR ≥ 300 km s-1, selected from RAVE DR5, SDSS DR12, LAMOST DR8, APOGEE DR16, GALAH DR2, and Gaia EDR3. In this sample, 52 are marginally hypervelocity star (HVS) candidates that have V GSR exceeding their local escape velocities within 2σ confidence levels, 40 of which are discovered for the first time. All of the candidates are metal-poor, late-type halo stars, which are significantly different from the previously identified HVSs, which are largely massive early-type stars, discovered by extreme radial velocity. This finding suggests that our newly identified HVS candidates are ejected by different mechanisms from the previous population. To investigate their origins, for 547 extreme velocity stars with V GSR ≥ 0.8V esc, we reconstruct their backward-integrated trajectories in the Galactic potential. According to the orbital analysis, no candidates are found to be definitely ejected from the Galactic-center (GC), while eight metal-poor extreme velocity stars are found to have a closest distance to the GC within 1 kpc. Intriguingly, 15 extreme velocity stars (including 2 HVS candidates) are found to have experienced close encounters with the Sagittarius dSph, suggesting that they originated from this dSph. This hypothesis is supported by an analysis of the [α/Fe]-[Fe/H] diagram. From a preliminary analysis of all of the 547 extreme velocity stars, we propose a general picture-star ejection from Galactic subsystems such as dwarf galaxies and globular clusters can be an important channel to produce extreme velocity stars or even HVSs, particularly the metal-poor late-type halo population.

Keywords: Black holes, Hypervelocity stars, Galaxy dynamics, Galaxy kinematics, Sagittarius dwarf spheroidal galaxy
Automated SpectroPhotometric Image REDuction (ASPIRED). We provide a suite of public open-source spectral data-reduction software to rapidly obtain scientific products from all forms of long-slit-like spectroscopic observations. Automated SpectroPhotometric REDuction (ASPIRED) is a PYTHON-based spectral data-reduction toolkit. It is designed to be a general toolkit with high flexibility for users to refine and optimize their data-reduction routines for the individual characteristics of their instruments. The default configuration is suitable for low-resolution long-slit spectrometers and provides a quick-look quality output. However, for repeatable science-ready reduced spectral data, some moderate one-time effort is necessary to modify the configuration. Fine-tuning and additional (pre)processing may be required to extend the reduction to systems with more complex setups. It is important to emphasize that although only a few parameters need updating, ensuring their correctness and suitability for generalization to the instrument can take time due to factors such as instrument stability. We compare some example spectra reduced with ASPIRED to published data processed with IRAF-based and STARLINK-based pipelines, and find no loss in the quality of the final product. The PYTHON-based, IRAF-free ASPIRED can significantly ease the effort of an astronomer in constructing their own data-reduction workflow, enabling simpler solutions to data-reduction automation. This availability of near-real-time, science-ready data will allow adaptive observing strategies, particularly important in, but not limited to, time-domain astronomy.

Keywords: Publicly available software, Observational astronomy, Open source software, Astronomy software, Astronomical techniques, Spectroscopy, Astronomical methods, Astronomy data reduction