Sazuna/UAT_keywords huggingface dataset:
The Continuing Search for Evidence of Tidal Orbital Decay of Hot Jupiters. Many of the known hot Jupiters are formally unstable to tidal orbital decay. The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit-timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of ${dP}/{dt}\approx {10}^{-9}, corresponding to a reduced tidal quality factor of about 2 × 105. Here, we present a compilation of transit-timing data for WASP-12 and 11 other systems that are especially favorable for detecting orbital decay: KELT-16; WASP-18, 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56. For most of these systems we present new data that extend the time baseline over which observations have been performed. None of the systems besides WASP-12 display convincing evidence for period changes, with typical upper limits on dP/dt on the order of 10-9 or 10-10, and lower limits on the reduced tidal quality factor on the order of 105. One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity. Further observations are encouraged.

Keywords: Exoplanet tides, Transits, Exoplanets
TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission. We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P = 3.6772 ± 0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius ( ${R}_{b}={1.34}_{-0.15}^{+0.26}{R}_{{\rm{J}}} ). We obtained high-resolution spectroscopic observations with the FIES, Ondřejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be Mb = 53.7 ± 1.2 ${M}_{{\rm{J}}} . The host star has a mass of M⋆ = 1.80 ± 0.06 M☉, a radius of R⋆ = 1.70 ± 0.05R☉, an effective temperature of Teff = 7650 ± 160 K, and a relatively high metallicity of 0.61 ± 0.07 dex. We used stellar isochrones to derive the age of the system to be ∼180 Myr, which places its age between that of RIK 72b (a ∼10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a ∼600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting main-sequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert ( $35\mbox{--}55{M}_{{\rm{J}}}\sin i ) is reforesting.

Keywords: Brown dwarfs, Stellar ages, Am stars, Stellar astronomy, Spectroscopy, Stellar rotation, Radial velocity, Transit photometry
MUSE Observations of NGC330 in the Small Magellanic Cloud: Helium Abundance of Bright Main-sequence Stars. We present observations of the most bright main-sequence stars in the Small Magellanic Cloud stellar cluster NGC 330 obtained with the integral-field spectrograph, the Multi Unit Spectroscopic Explorer, at the Very Large Telescope. The use of this valuable instrument allows us to study both photometric and spectroscopic properties of stellar populations of this young star cluster. The photometric data provide us a precise color-magnitude diagram, which seems to support the presence of two stellar populations of ages of ≍18 Myr and ≍30 Myr assuming a metallicity of Z = 0.002. Thanks to the spectroscopic data, we derive a helium abundance of 10 main-sequence stars within the effective radius of Reff = 20″ of NGC 330, thus leading to an estimation of $ \langle \epsilon ({\rm{He}}) \rangle = 10.93 ± 0.05(1σ). The helium elemental abundances of stars likely belonging to the two possible stellar populations do not show differences or dichotomy within the uncertainties. Thus, our results suggest that the two stellar populations of NGC 330, if they exist, share similar original He abundances. If we consider stellar rotation velocity in our analysis, a coeval (30 Myr) stellar population, experiencing different values of rotation, cannot be excluded. In this case, the mean helium abundance $\langle \epsilon (\mathrm{He}){\rangle }_{\mathrm{rot}} obtained in our analysis is 11.00 ± 0.05 dex. We also verified that possible non-LTE (NLTE) effects cannot be identified with our analysis because of the spectral resolution and they are within our derived abundance He uncertainties. Moreover, the analysis of the He abundance as a function of the distance from the cluster center of the observed stars does not show any correlation.

Keywords: Stellar abundances, Small Magellanic Cloud, Star clusters
Census of the Young Stellar Population in the Galactic H II Region Sh2-242. We present here identification and characterization of the young stellar population associated with an active star-forming site Sh2-242. We used our own new optical imaging and spectroscopic observational data, as well as several archival catalogs, e.g., Pan-STARRS 1, Gaia DR2, IPHAS, Wide-field InfraRed Camera, 2MASS, and Spitzer. Slit spectroscopic results confirm the classification of the main ionizing source BD+26 980 as an early-type star of spectral type B0.5 V. The spectrophotometric distance of the star is estimated as 2.08 ± 0.24 kpc, which confirms the source as a member of the cluster. An extinction map covering a large area (diameter ∼50') is generated with H and K photometry toward the region. From the map, three distinct locations of peak extinction complexes (AV ≃ 7-17 mag) are identified for the very first time. Using the infrared color excess, a total of 33 Class I and 137 Class II young objects are classified within the region. The IPHAS photometry reveals classification of 36 Hα emitting sources, which might be class II objects. Among 36 Hα emitting sources, 5 are already identified using infrared excess emission. In total, 201 young objects are classified toward S242 from this study. The membership status of the young sources is further windowed with the inclusion of parallax from the Gaia DR2 catalog. Using the optical and infrared color-magnitude diagrams, the young stellar objects are characterized with an average age of ∼1 Myr and masses in the range 0.1-3.0 M☉. The census of the stellar content within the region is discussed using combined photometric and spectroscopic data.

Keywords: Infrared excess, Extinction, Pre-main sequence stars, Star formation, H II regions
Scaling K2. II. Assembly of a Fully Automated C5 Planet Candidate Catalog Using EDI-Vetter. We present a uniform transiting exoplanet candidate list for Campaign 5 of the K2 mission. This catalog contains 75 planets with seven multi-planet systems (five double, one triple, and one quadruple planet system). Within the range of our search, we find eight previously undetected candidates, with the remaining 67 candidates overlapping 51% of the study of Kruse et al. that manually vets candidates from Campaign 5. In order to vet our potential transit signals, we introduce the Exoplanet Detection Identification Vetter (EDI-Vetter), which is a fully automated program able to determine whether a transit signal should be labeled as a false positive or a planet candidate. This automation allows us to create a statistically uniform catalog, ideal for measurements of planet occurrence rate. When tested, the vetting software is able to ensure that our sample is 94.2% reliable against systematic false positives. Additionally, we inject artificial transits at the light-curve level of the raw K2 data and find that the maximum completeness of our pipeline is 70% before vetting and 60% after vetting. For convenience of future studies of occurrence rate, we include measurements of stellar noise (CDPP) and the three-transit window function for each target. This study is part of a larger survey of the K2 data set and the methodology that will be applied to the entirety of that set.

Keywords: Exoplanet catalogs, Astronomy data analysis, Planetary science
An Analysis of the Statistics and Systematics of Limb Anomaly Detections in HST/STIS Transit Images of Europa. Several recent studies derived the existence of plumes on Jupiter's moon Europa. The only technique that provided multiple detections is the far-ultraviolet imaging observations of Europa in transit of Jupiter taken by the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST). In this study, we reanalyze the three HST/STIS transit images in which Sparks et al. identified limb anomalies as evidence for Europa's plume activity. After reproducing the results of Sparks et al., we find that positive outliers are similarly present in the images as the negative outliers that were attributed to plume absorption. A physical explanation for the positive outliers is missing. We then investigate the systematic uncertainties and statistics in the images and identify two factors that are crucial when searching for anomalies around the limb. One factor is the alignment between the actual and assumed locations of Europa on the detector. A misalignment introduces distorted statistics, most strongly affecting the limb above the darker trailing hemisphere where the plumes were detected. The second factor is a discrepancy between the observation and the model used for comparison, adding uncertainty in the statistics. When accounting for these two factors, the limb minima (and maxima) are consistent with random statistical occurrence in a sample size given by the number of pixels in the analyzed limb region. The plume candidate features in the three analyzed images can be explained by purely statistical fluctuations and do not provide evidence for absorption by plumes.

Keywords: Hubble Space Telescope, Astrostatistics techniques, Galilean satellites, Ultraviolet photometry
Permittivity Estimation of Subsurface Deposits in the Elysium-Utopia Region on Mars with MRO Shallow Radar Sounder Data. Dielectric properties of the subsurface layers provide important clues to material compositions beneath the surface. The Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) observed clear subsurface reflections in the Elysium-Utopia region, where morphological features such as impact craters with rampart ejecta suggest the possible presence of volatiles, but the permittivity of the subsurface unit beneath the surface strata has not been derived yet to provide independent evidence for or against the presence of water ice. In this paper, we employed a three-layer model consisting a surface mantling layer (layer I), a shallow subsurface layer (layer II), and a deep subsurface layer (layer III) to invert the permittivity of layer III, which considers the surface roughness and attenuation of radar waves in layer II. The obtained permittivity and loss tangent in the study region confirm that the materials of layer II are dense basaltic flows. Then, the permittivity of layer III is derived as 2.6 ± 0.9, suggesting that subsurface water ice may be present, or a layer of dry and low-density deposits exists beneath the basalt layer. The hypothesis could be further tested by the ground-penetrating radar of China's first Martian mission, to be launched in 2020. Our results also show that the surface mantling layer included in the model is essential in the calculation of permittivity values.

Keywords: Mars, Martian satellites, Radar astronomy, Computational methods
New Insights into the Chemical Composition of Five Oort Cloud Comets after Re-analysis of Their Infrared Spectra. We present revised results for the main molecular species in five Oort Cloud comets observed with near-infrared echelle grating spectrometer (NIRSPEC) at the Keck Observatory between 1999 and 2012 (C/1999 S4 (LINEAR), C/2001 A2 (LINEAR), C/2007 W1 (Boattini), C/2012 F6 (Lemmon), and C/2012 S1 (ISON)). The re-evaluation of these data shows the improvement of results in some of the data sets, in particular for comets observed and analyzed before the advent of new and revised fluorescence models and terrestrial retrieval methods introduced since 2011. We observe significant improvements in the resulting rotational temperatures and the production rates for all species, and in mixing ratios of minor species (relative to water). The re-analysis also allowed us to quantify species not analyzed previously, mostly due to the lack of molecular models (e.g., ammonia and formaldehyde). We note, however, that the improvement of these revised values is less substantial for comets observed (and/or analyzed) since 2010.

Keywords: Comets, Astrobiology, Solar system formation
Additional Calibration of the Ultraviolet Imaging Telescope on Board AstroSat. Results of the initial calibration of the Ultra-Violet Imaging Telescope (UVIT) were reported earlier by Tandon et al. The results reported earlier were based on the ground calibration as well as the first observations in orbit. Some additional data from the ground calibration and data from more in-orbit observations have been used to improve the results. In particular, extensive new data from in-orbit observations have been used to obtain (a) new photometric calibration that includes (i) zero points, (ii) flat fields, and (iii) saturation; (b) sensitivity variations; (c) spectral calibration for the near ultraviolet (NUV; 2000-3000 Å) and far ultraviolet (FUV; 1300-1800 Å) gratings; (d) point-spread function; and (e) astrometric calibration including distortion. Data acquired over the last three years show continued good performance of UVIT with no reduction in sensitivity in both UV channels.

Keywords: Ultraviolet telescopes, Ultraviolet astronomy, Astronomical instrumentation, Ultraviolet photometry, Spectroscopy
The Intrinsic Scatter of the Broad Lines-Narrow Line Correlation in Type I AGN. A correlation between the FWHM of the broad Balmer lines and the narrow [O III]/Hβ line ratio was recently applied to the black hole (BH) mass estimation in type II active galactic nuclei (AGN), where only the narrow lines are visible to the observer. The correlation was initially quantified with type I AGN using stacked spectra, in groups automatically created using a machine-learning algorithm. Such an analysis does not provide information about the intrinsic scatter of the correlation. In addition, it does not necessarily reproduce the true underlying correlation, for example, due to the stacking of spectra with different properties. Testing these two issues requires measurements of individual objects. In this work, we perform such a test by fitting the broad and narrow lines for 8302 type I AGN from the Sloan Digital Sky Survey. Due to the difficulty in reliably measuring the narrow Balmer lines in such objects, which are, in many cases, a small contribution on top of the broad lines, we visually inspect all of the fits and identify 1561 objects with robust measurements. Using these measurements, we find that while a correlation does exist, it shows a large scatter and is not well described by a linear relation. This should be taken into account when using the broad Hβ FWHM versus narrow [O III]/Hβ correlation for type II AGN BH mass estimation.

Keywords: Supermassive black holes, Active galaxies, Active galactic nuclei
LHS 1815b: The First Thick-disk Planet Detected by TESS. We report the first discovery of a thick-disk planet, LHS 1815b (TOI-704b, TIC 260004324), detected in the Transiting Exoplanet Survey Satellite (TESS) survey. LHS 1815b transits a bright (V = 12.19 mag, K = 7.99 mag) and quiet M dwarf located 29.87 ± 0.02 pc away with a mass of 0.502 ± 0.015 M☉ and a radius of 0.501 ± 0.030 R☉. We validate the planet by combining space- and ground-based photometry, spectroscopy, and imaging. The planet has a radius of 1.088 ± 0.064 R⊕ with a 3σ mass upper limit of 8.7 M⊕. We analyze the galactic kinematics and orbit of the host star LHS 1815 and find that it has a large probability (Pthick/Pthin = 6482) to be in the thick disk with a much higher expected maximal height (Zmax = 1.8 kpc) above the Galactic plane compared with other TESS planet host stars. Future studies of the interior structure and atmospheric properties of planets in such systems using, for example, the upcoming James Webb Space Telescope, can investigate the differences in formation efficiency and evolution for planetary systems between different Galactic components (thick disks, thin disks, and halo).

Keywords: Astrometric exoplanet detection, Stellar kinematics, Astrometry, Radial velocity, Transit photometry
Solar Contamination in Extreme-precision Radial-velocity Measurements: Deleterious Effects and Prospects for Mitigation. Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ∼10 cm s-1 sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s-1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments.

Keywords: High resolution spectroscopy, Astronomy data analysis, Exoplanet astronomy, Sky brightness, Radial velocity
Quantitative and Qualitative Results from Orbital Plane Precession of Medium-high Near-circular Orbits. The theoretical analysis of Allan &amp; Cook on the mechanisms of orbital plane precession for medium-high circular orbits is briefly reviewed, and the fact that there are two types of possible precession mechanisms (not only the classical Laplace precession) for the long-term evolution of the orbital plane of medium-high near-circular orbits is especially emphasized. Based on two types of possible precession mechanisms, the analytical formulae of the quantitative variation ranges of orbital inclination derived by Zhao et al. are revised, and the complete analytical formulae for medium-high near-circular orbits are obtained. The qualitative characteristic formula for the variation of orbital inclination-longitude of the ascending node of geostationary orbits in Zhao et al. is generalized to medium-high near-circular orbits, and the more general analytical formulae are obtained. Taking the near-circular orbits with the altitudes as the geosynchronous and medium orbits of the BeiDou navigation satellites as examples, the theoretically quantitative and qualitative results from orbital plane precession are verified by the first-order semianalytical calculations with simplified models and numerical calculations with precise models to a certain extent. Moreover, the specific quantitative and qualitative results for medium-high near-circular orbits with the given initial inclinations and different initial longitudes of the ascending node are particularly presented, from which some conclusions are summarized. Due to the high similarity of orbital plane precession for natural satellites to that of artificial satellites, the results and methodology in this paper can be directly extended to the long-term evolution of the orbital plane for natural satellites and help to understand and explain some orbit dynamic phenomena of natural satellites.

Keywords: Celestial mechanics, Orbits, Orbital motion
Multiband Probabilistic Cataloging: A Joint Fitting Approach to Point-source Detection and Deblending. Probabilistic cataloging (PCAT) outperforms traditional cataloging methods on single-band optical data in crowded fields. We extend our work to multiple bands, achieving greater sensitivity (∼0.4 mag) and greater speed (500×) compared to previous single-band results. We demonstrate the effectiveness of multiband PCAT on mock data, in terms of both recovering accurate posteriors in the catalog space and directly deblending sources. When applied to Sloan Digital Sky Survey (SDSS) observations of M2, taking Hubble Space Telescope data as truth, our joint fit on r- and i-band data goes ∼0.4 mag deeper than single-band probabilistic cataloging and has a false discovery rate less than 20% for F606W ≤ 20. Compared to DAOPHOT, the two-band SDSS catalog fit goes nearly 1.5 mag deeper using the same data and maintains a lower false discovery rate down to F606W ∼ 20.5. Given recent improvements in computational speed, multiband PCAT shows promise in application to large-scale surveys and is a plausible framework for joint analysis of multi-instrument observational data. https://github.com/RichardFeder/multiband_pcat.

Keywords: Globular star clusters, Bayesian statistics, Sky surveys, Star counts, Hierarchical models, Catalogs
Photometric Biases in Modern Surveys. Many surveys use maximum-likelihood (ML) methods to fit models when extracting photometry from images. We show that these ML estimators systematically overestimate the flux as a function of the signal-to-noise ratio and the number of model parameters involved in the fit. This bias is substantially worse for resolved sources: while a 1% bias is expected for a 10σ point source, a 10σ resolved galaxy with a simplified Gaussian profile suffers a 2.5% bias. This bias also behaves differently depending how multiple bands are used in the fit: simultaneously fitting all bands leads the flux bias to become roughly evenly distributed between them, while fixing the position in "non-detection" bands (i.e., forced photometry) gives flux estimates in those bands that are biased low, compounding a bias in derived colors. We show that these effects are present in idealized simulations, outputs from the Hyper Suprime-Cam fake-object pipeline (SynPipe), and observations from Sloan Digital Sky Survey Stripe 82. Prescriptions to correct for the ML bias in flux, and its uncertainty, are provided.

Keywords: CCD photometry, Fisher's Information, Surveys, Catalogs, Astronomy data analysis, Astrostatistics, Maximum likelihood estimation, Astronomy data reduction