Sazuna/UAT_keywords huggingface dataset:
Rotation of Low-mass Stars in Taurus with K2. We present an analysis of K2 light curves (LCs) from Campaigns 4 and 13 for members of the young (∼3 Myr) Taurus association, in addition to an older (∼30 Myr) population of stars that is largely in the foreground of the Taurus molecular clouds. Out of 156 of the highest-confidence Taurus members, we find that 81% are periodic. Our sample of young foreground stars is biased and incomplete, but nearly all stars (37/38) are periodic. The overall distribution of rotation rates as a function of color (a proxy for mass) is similar to that found in other clusters: the slowest rotators are among the early M spectral types, with faster rotation toward both earlier FGK and later M types. The relationship between period and color/mass exhibited by older clusters such as the Pleiades is already in place by Taurus age. The foreground population has very few stars but is consistent with the USco and Pleiades period distributions. As found in other young clusters, stars with disks rotate on average slower, and few with disks are found rotating faster than ∼2 days. The overall amplitude of the LCs decreases with age, and higher-mass stars have generally lower amplitudes than lower-mass stars. Stars with disks have on average larger amplitudes than stars without disks, though the physical mechanisms driving the variability and the resulting LC morphologies are also different between these two classes.

Keywords: Starspots, Stellar rotation, Star formation
Pluto's Ultraviolet Spectrum, Surface Reflectance, and Airglow Emissions. During the New Horizons spacecraft's encounter with Pluto, the Alice ultraviolet spectrograph conducted a series of observations that detected emissions from both the interplanetary medium (IPM) and Pluto. In the direction of Pluto, the IPM was found to be 133.4 ± 0.6 R at Lyα, 0.24 ± 0.02 R at Lyβ, and &lt;0.10 R at He I 584 Å. We analyzed 3900 s of data obtained shortly before closest approach to Pluto and detect airglow emissions from H I, N I, N II, N2, and CO above the disk of Pluto. We find Pluto's brightness at Lyα to be 29.3 ± 1.9 R, in good agreement with preencounter estimates. The detection of the N II multiplet at 1085 Å marks the first direct detection of ions in Pluto's atmosphere. We do not detect any emissions from noble gases and place a 3σ upper limit of 0.14 R on the brightness of the Ar I 1048 Å line. We compare preencounter model predictions and predictions from our own airglow model, based on atmospheric profiles derived from the solar occultation observed by New Horizons, to the observed brightness of Pluto's airglow. Although completely opaque at Lyα, Pluto's atmosphere is optically thin at wavelengths longer than 1425 Å. Consequently, a significant amount of solar far-UV light reaches the surface, where it can participate in space weathering processes. From the brightness of sunlight reflected from Pluto, we find the surface has a reflectance factor (I/F) of 17% between 1400 and 1850 Å. We also report the first detection of a C3 hydrocarbon molecule, methylacetylene, in absorption, at a column density of ∼5 × 1015 cm-2, corresponding to a column-integrated mixing ratio of 1.6 × 10-6.

Keywords: Planetary surfaces, Planetary atmospheres, Ultraviolet astronomy, Spectrometers, Pluto
A Coupled Analysis of Atmospheric Mass Loss and Tidal Evolution in XUV Irradiated Exoplanets: The TRAPPIST-1 Case Study. Exoplanets residing close to their stars can experience evolution of both their physical structures and their orbits due to the influence of their host stars. In this work, we present a coupled analysis of dynamical tidal dissipation and atmospheric mass loss for exoplanets in X-ray and ultraviolet (XUV) irradiated environments. As our primary application, we use this model to study the TRAPPIST-1 system and place constraints on the interior structure and orbital evolution of the planets. We start by reporting on an ultraviolet continuum flux measurement (centered around ∼1900 Å) for the star TRAPPIST-1, based on 300 ks of Neil Gehrels Swift Observatory data, and which enables an estimate of the XUV-driven thermal escape arising from XUV photodissociation for each planet. We find that the X-ray flaring luminosity, measured from our X-ray detections, of TRAPPIST-1 is 5.6 × 10-4 L*, while the full flux including non-flaring periods is 6.1 × 10-5 L*, when L* is TRAPPIST-1's bolometric luminosity. We then construct a model that includes both atmospheric mass loss and tidal evolution and requires the planets to attain their present-day orbital elements during this coupled evolution. We use this model to constrain the ratio $Q^{\prime} =3Q/2{k}_{2}$ for each planet. Finally, we use additional numerical models implemented with the Virtual Planet Simulator VPLanet to study ocean retention for these planets using our derived system parameters.

Keywords: Extrasolar rocky planets, Exoplanet atmospheres, Exoplanet structure, Exoplanets
Proper-motion Membership Tests for Four Planetary Nebulae in Galactic Globular Clusters. Four planetary nebulae (PNe) are considered to be probable or possible members of Galactic globular clusters (GCs). These are Ps 1 = K648 in M15, GJJC 1 = IRAS 18333-2357 in M22, JaFu 1 in Palomar 6, and JaFu 2 in NGC 6441. In addition to lying close to the host GCs on the sky, these PNe have radial velocities that are consistent, within the errors and stellar velocity dispersions, with cluster membership. The remaining membership criterion is whether the proper motions (PMs) of the central stars are in agreement with those of the host clusters. We have carried out the PM test for all four PNe. Two of the central stars—those of Ps 1 and GJJC 1—have PMs listed in the recent Gaia Data Release 2 (DR2). We updated the PM of the Ps 1 central star to a more precise value using archival Hubble Space Telescope (HST) frames. Both PMs are statistically consistent with cluster membership. For the other two PNe, we used archival HST images to derive the PMs of their nuclei. For JaFu 2, there are HST images at several epochs, and the measured PM of the nucleus is in excellent agreement with that of the host cluster. For JaFu 1 the available archival HST images are less optimal and the results are less conclusive; the measured PM for the central star is marginally consistent with cluster membership, but additional astrometric observations are desirable for a more robust membership test. * Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Keywords: Globular star clusters, Binary stars, Planetary nebulae nuclei, Planetary nebulae, Space astrometry
A Numerical Method for Determining the Elements of Circumbinary Orbits and Its Application to Circumbinary Planets and the Satellites of Pluto-Charon. Planets and satellites orbiting a binary system exist in the solar system and extrasolar planetary systems. Their orbits can be significantly different from Keplerian orbits, if they are close to the binary and the secondary-to-primary mass ratio is high. A proper description of a circumbinary orbit is in terms of the free eccentricity efree at the epicyclic frequency κ0, forced eccentricity eforced at the mean motion n0, and oscillations at higher frequencies forced by the non-axisymmetric components of the binary's potential. We show that accurate numerical values for the amplitudes and frequencies of these terms can be extracted from numerical orbit integrations by applying fast Fourier transformation (FFT) to the cylindrical distance between the circumbinary object and the center of mass of the binary as a function of time. We apply this method to three Kepler circumbinary planets and the satellites of Pluto-Charon. For the satellite Styx of Pluto-Charon, the FFT results for κ0 and efree differ significantly from the first-order analytic value and the value reported by Showalter &amp; Hamilton, respectively. We show that the deviation in κ0 is likely due to the effect of the 3:1 mean-motion resonance and discuss the implications of the lower value for efree.

Keywords: Exoplanet dynamics, Binary stars, Orbital elements, Exoplanets, Natural satellites (Solar system), Celestial mechanics, Pluto
Constraints on Metastable Helium in the Atmospheres of WASP-69b and WASP-52b with Ultranarrowband Photometry. Infrared observations of metastable 23S helium absorption with ground- and space-based spectroscopy are rapidly maturing, as this species is a unique probe of exoplanet atmospheres. Specifically, the transit depth in the triplet feature (with vacuum wavelengths near 1083.3 nm) can be used to constrain the temperature and mass-loss rate of an exoplanet's upper atmosphere. Here, we present a new photometric technique to measure metastable 23S helium absorption using an ultranarrowband filter (FWHM 0.635 nm) coupled to a beam-shaping diffuser installed in the Wide-field Infrared Camera on the 200 inch Hale Telescope at Palomar Observatory. We use telluric OH lines and a helium arc lamp to characterize refractive effects through the filter and to confirm our understanding of the filter transmission profile. We benchmark our new technique by observing a transit of WASP-69b and detect an excess absorption of 0.498% ± 0.045% (11.1σ), consistent with previous measurements after considering our bandpass. We then use this method to study the inflated gas giant WASP-52b and place a 95th percentile upper limit on excess absorption in our helium bandpass of 0.47%. Using an atmospheric escape model, we constrain the mass-loss rate for WASP-69b to be ${5.25}_{-0.46}^{+0.65}\times {10}^{-4}\,{M}_{{\rm{J}}}\,{\mathrm{Gyr}}^{-1}$ ( ${3.32}_{-0.56}^{+0.67}\times {10}^{-3}\,{M}_{{\rm{J}}}\,{\mathrm{Gyr}}^{-1}$ ) at 7000 K (12,000 K). Additionally, we set an upper limit on the mass-loss rate of WASP-52b at these temperatures of $2.1\times {10}^{-4}\,{M}_{{\rm{J}}}\,{\mathrm{Gyr}}^{-1}$ ( $2.1\times {10}^{-3}\,{M}_{{\rm{J}}}\,{\mathrm{Gyr}}^{-1}$ ). These results show that ultranarrowband photometry can reliably quantify absorption in the metastable helium feature.

Keywords: Exoplanet atmospheres, Planetary atmospheres, Transmission spectroscopy, Exoplanet astronomy, Narrow band photometry, Infrared photometry
A Probabilistic Approach to Kepler Completeness and Reliability for Exoplanet Occurrence Rates. Exoplanet catalogs produced by surveys suffer from a lack of completeness (not every planet is detected) and less than perfect reliability (not every planet in the catalog is a true planet), particularly near the survey's detection limit. Exoplanet occurrence rate studies based on such a catalog must be corrected for completeness and reliability. The final Kepler data release, DR25, features a uniformly vetted planet candidate catalog and data products that facilitate corrections. We present a new probabilistic approach to the characterization of Kepler completeness and reliability, making full use of the Kepler DR25 products. We illustrate the impact of completeness and reliability corrections with a Poisson-likelihood occurrence rate method, using a recent stellar properties catalog that incorporates Gaia stellar radii and essentially uniform treatment of the stellar population. Correcting for reliability has a significant impact: the exoplanet occurrence rate for orbital period and radius within 20% of Earth's around GK dwarf stars, corrected for reliability, is ${0.015}_{-0.007}^{+0.011}$ , whereas not correcting results in ${0.034}_{-0.012}^{+0.018}$ —correcting for reliability reduces this occurrence rate by more than a factor of two. We further show that using Gaia-based versus DR25 stellar properties impacts the same occurrence rate by a factor of two. We critically examine the the DR25 catalog and the assumptions behind our occurrence rate method. We propose several ways in which confidence in both the Kepler catalog and occurrence rate calculations can be improved. This work provides an example of how the community can use the DR25 completeness and reliability products.

Keywords: Exoplanet detection methods, Exoplanet catalogs, Exoplanets
The Gaia-Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars. An accurate and precise Kepler Stellar Properties Catalog is essential for the interpretation of the Kepler exoplanet survey results. Previous Kepler Stellar Properties Catalogs have focused on reporting the best-available parameters for each star, but this has required combining data from a variety of heterogeneous sources. We present the Gaia-Kepler Stellar Properties Catalog, a set of stellar properties of 186,301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available. Our photometric effective temperatures, derived from $g\,\mathrm{to}\,{K}_{s}$ colors, are calibrated on stars with interferometric angular diameters. Median catalog uncertainties are 112 K for ${T}_{\mathrm{eff}}$ , 0.05 dex for $\mathrm{log}\,g$ , 4% for ${R}_{\star }$ , 7% for ${M}_{\star }$ , 13% for ${\rho }_{\star }$ , 10% for ${L}_{\star }$ , and 56% for stellar age. These precise constraints on stellar properties for this sample of stars will allow unprecedented investigations into trends in stellar and exoplanet properties as a function of stellar mass and age. In addition, our homogeneous parameter determinations will permit more accurate calculations of planet occurrence and trends with stellar properties.

Keywords: Fundamental parameters of stars, Exoplanet systems, Catalogs
An Information Theoretic Framework for Classifying Exoplanetary System Architectures. We propose several descriptive measures to characterize the arrangements of planetary masses, periods, and mutual inclinations within exoplanetary systems. These measures are based on complexity theory and capture the global, system-level trends of each architecture. Our approach considers all planets in a system simultaneously, facilitating both intrasystem and intersystem analysis. We find that based on these measures, Kepler's high-multiplicity (N ≥ 3) systems can be explained if most systems belong to a single intrinsic population, with a subset of high-multiplicity systems (∼20%) hosting additional, undetected planets intermediate in period between the known planets. We confirm prior findings that planets within a system tend to be roughly the same size and approximately coplanar. We find that forward modeling has not yet reproduced the high degree of spacing similarity (in log-period) actually seen in the Kepler data. Although our classification scheme was developed using compact Kepler multis as a test sample, our methods can be immediately applied to any other population of exoplanetary systems. We apply this classification scheme to (1) quantify the similarity between systems, (2) resolve observational biases from physical trends, and (3) identify which systems to search for additional planets and where to look for these planets.

Keywords: Astroinformatics, Classification systems, Exoplanet systems
A Survey for New Stars and Brown Dwarfs in the Ophiuchus Star-forming Complex. We have performed a survey for new members of the Ophiuchus cloud complex using high-precision astrometry from the second data release of Gaia, proper motions measured with multi-epoch images from the Spitzer Space Telescope, and color-magnitude diagrams constructed with photometry from various sources. Through spectroscopy of candidates selected with those data, we have identified 155 new young stars. Based on available measurements of kinematics, we classify 102, 47, and 6 of those stars as members of Ophiuchus, Upper Sco, and other populations in Sco-Cen, respectively. We have also assessed the membership of all other stars in the vicinity of Ophiuchus that have spectroscopic evidence of youth from previous studies, arriving at a catalog of 373 adopted members of the cloud complex. For those adopted members, we have compiled mid-infrared photometry from Spitzer and the Wide-field Infrared Survey Explorer and have used mid-infrared colors to identify and classify circumstellar disks. We find that 210 of the members show evidence of disks, including 48 disks that are in advanced stages of evolution. Finally, we have estimated the relative median ages of the populations near the Ophiuchus clouds and the surrounding Upper Sco association using absolute K-band magnitudes (MK) based on Gaia parallaxes. If we adopt an age 10 Myr for Upper Sco, then the relative values of MK imply median ages of ∼2 Myr for L1689 and embedded stars in L1688, 3-4 Myr for low-extinction stars near L1688, and ∼6 Myr for the group containing ρ Oph.

Keywords: Low mass stars, Young stellar objects, Pre-main sequence stars, Brown dwarfs
Bayesian Methods for Joint Exoplanet Transit Detection and Systematic Noise Characterization. The treatment of systematic noise is a significant aspect of transit exoplanet data processing due to the signal strength of systematic noise relative to a transit signal. Typically, the standard approach to transit detection is to estimate and remove systematic noise independently of and prior to a transit detection test. If a transit signal is present in a light curve, the process of systematic noise removal may distort the transit signal by overfitting and thereby reduce detection efficiency. We present a Bayesian framework for joint detection of transit signals and systematic noise characterization and describe the implementation of these detectors as optimal Neyman-Pearson likelihood ratio tests. The joint detectors reduce to closed form as matched filters under the assumption of a Gaussian Bayesian prior for the systematic noise. The performance of the exploratory detectors was evaluated in injection tests and show ∼2% improvement in overall detection efficiency relative to the standard approach. We find that joint detection efficiency is specifically improved for short-period, low transit-depth exoplanet transits, providing evidence in support of the hypothesis that joint detection may indeed help to mitigate overfitting. In addition, an initial feasibility test to detect known exoplanets in Kepler data using the joint detectors produced encouraging preliminary results.

Keywords: Bayesian statistics, Exoplanets, Astronomy data analysis, Exoplanet detection methods, Transit photometry, Time series analysis, Red noise
Optimizing Simulation Parameters for Weak Lensing Analyses Involving Non-Gaussian Observables. We performed a series of numerical experiments to quantify the sensitivity of the predictions for weak lensing statistics obtained in ray-tracing dark matter (DM)-only simulations, to two hyper-parameters that influence the accuracy as well as the computational cost of the predictions: the thickness of the lens planes used to build past light cones and the mass resolution of the underlying DM simulation. The statistics considered are the power spectrum (PS) and a series of non-Gaussian observables, including the one-point probability density function, lensing peaks, and Minkowski functionals. Counterintuitively, we find that using thin lens planes (&lt; 60 h-1 Mpc on a 240 h-1 Mpc simulation box) suppresses the PS over a broad range of scales beyond what would be acceptable for a survey comparable to the Large Synoptic Survey Telescope (LSST). A mass resolution of 7.2 × 1011 h-1 M⊙ per DM particle (or 2563 particles in a (240 h-1 Mpc)3 box) is sufficient to extract information using the PS and non-Gaussian statistics from weak lensing data at angular scales down to 1' with LSST-like levels of shape noise.

Keywords: Weak gravitational lensing, Computational methods, Large-scale structure of the universe
Orbital Precession in the Distant Solar System: Further Constraining the Planet Nine Hypothesis with Numerical Simulations. The longitudes of perihelia and orbital poles of the solar system's dozen or so most remote detected objects are clustered in a manner inconsistent with that of a random sample of uniformly distributed orbits. While small number statistics and observational biases may explain these features, the statistical significance of the clustering has led to the recent development of the "Planet Nine hypothesis." In the proposed scenario, orbits in the distant solar system are shepherded via secular perturbations from an undetected massive planet on an eccentric orbit. However, the precession of perihelia and nodes in the outer Kuiper Belt and inner Oort cloud are also affected by the giant planets, passing stars, and the galactic tide. We perform a large suite of numerical simulations designed to study the orbital alignment of extreme trans-Neptunian objects (ETNOs) and inner Oort cloud objects (IOCOs). In our various integrations that include Planet Nine, we consistently find that ≳60% of ETNOs and IOCOs that are detectable after 4 Gyr are also anti-aligned in perihelia with the distant massive perturber. However, when we randomly select 17 objects from this sample of remaining orbits, there is significant scatter in the degree of longitude of perihelion and orbital pole clustering that might be observed. Furthermore, we argue that, in the absence of Planet Nine, 17 randomly drawn orbits should still exhibit some clustering even if the underlying distribution is uniform. Thus, we find that still more ETNO and IOCO detections are required to confidently infer the presence of Planet Nine.

Keywords: Small Solar System bodies, Solar system formation, Solar system, Solar system gas giant planets
Toward Complete Characterization: Prospects for Directly Imaging Transiting Exoplanets. High-contrast direct imaging of exoplanets can provide many important observables, including measurements of the orbit, spectra that probe the lower layers of the atmosphere, and phase variations of the planet, but cannot directly measure planet radius or mass. Our future understanding of directly imaged exoplanets will therefore rely on extrapolated models of planetary atmospheres and bulk composition, which need robust calibration. We estimate the population of extrasolar planets that could serve as calibrators for these models. Critically, this population of "standard planets" must be accessible to both direct imaging and the transit method, allowing for radius measurement. We show that the search volume of a direct imaging mission eventually overcomes the transit probability falloff with semimajor axis, so that as long as cold planets are not exceedingly rare, the population of transiting planets and directly imageable planets overlaps. Using current extrapolations of Kepler occurrence rates, we estimate that ∼8 standard planets could be characterized shortward of 800 nm with an ambitious future direct imaging mission like LUVOIR-A and several dozen could be detected at the V band. We show the design space that would expand the sample size and discuss the extent to which ground- and space-based surveys could detect this small but crucial population of planets.

Keywords: Transits, Astrometric exoplanet detection, Exoplanets, Radial velocity, Coronagraphic imaging, Direct imaging, Space telescopes, Exoplanet detection methods
A Larger Extent for the Ophiuchus Stream. We present new kinematic data for the Ophiuchus stellar stream. Spectra have been taken of member candidates at the MMT telescope using Hectospec, Hectochelle, and Binospec, which provide more than 1800 new velocities. Combined with proper-motion measurements of stars in the field by the Gaia—DR2 catalog, we have derived stream membership probabilities, resulting in the detection of more than 200 likely members. These data show the stream extends to more than three times the length shown in the discovery data. A spur to the main stream is also detected. The high-resolution spectra allow us to resolve the stellar velocity dispersion, found to be 1.6 ± 0.3 km s-1.

Keywords: Galaxy stellar halos, Milky Way stellar halo, Galaxy structure, Globular star clusters