Sazuna/UAT_keywords huggingface dataset:
Orbits of Five Triple Stars. Joint analysis of radial velocities and position measurements of five hierarchical stellar systems is undertaken to determine elements of their inner and outer orbits and, whenever possible, their mutual inclinations. The inner and outer periods are 12.9 and 345 yr for HD 12376 (ADS 1613), 1.14 and ∼1500 yr for HD 19971 (ADS 2390), 8.3 and 475 yr for HD 89795 (ADS 7338), 1.11 and 40 yr for HD 152027, 0.69 and 7.4 yr for HD 190412. The latter system with its coplanar and quasi-circular orbits belongs to the family of compact planetary-like hierarchies, while the orbits in HD 12376 have a mutual inclination of 131°.

Keywords: Spectroscopic binary stars, Visual binary stars
Searching for ZZ Ceti White Dwarfs in the Gaia Survey. The Gaia satellite recently released parallax measurements for ∼260,000 high-confidence white dwarf candidates, allowing for precise measurements of their physical parameters. By combining these parallaxes with Pan-STARRS and u-band photometry, we measured the effective temperature and stellar mass for all white dwarfs in the Northern Hemisphere within 100 pc of the Sun, and identified a sample of ZZ Ceti white dwarf candidates within the so-called instability strip. We acquired high-speed photometric observations for 90 candidates using the PESTO camera attached to the 1.6 m telescope at the Mont-Mégantic Observatory. We report the discovery of 38 new ZZ Ceti stars, including two very rare ultramassive pulsators. We also identified five possibly variable stars within the strip, in addition to 47 objects that do not appear to show any photometric variability. However, several of those could be variable with an amplitude below our detection threshold, or could be located outside the instability strip due to errors in their photometric parameters. In the light of our results, we explore the trends of the dominant period and amplitude in the M- ${T}_{\mathrm{eff}}$ plane, and briefly discuss the question of the purity of the ZZ Ceti instability strip (i.e., a region devoid of non-variable stars).

Keywords: Fundamental parameters of stars, White dwarf stars, ZZ Ceti stars, Pulsating variable stars
An Increase in Small-planet Occurrence with Metallicity for Late-type Dwarf Stars in the Kepler Field and Its Implications for Planet Formation. While it is well-established that giant-planet occurrence rises rapidly with host star metallicity, it is not yet clear if small-planet occurrence around late-type dwarf stars depends on host star metallicity. Using the Kepler Data Release 25 planet candidate list and its completeness data products, we explore planet occurrence as a function of metallicity in the Kepler field's late-type dwarf stellar population. We find that planet occurrence increases with metallicity for all planet radii Rp down to at least Rp ≈ 2 R⊕, and that in the range 2 R⊕ ≲ Rp ≲ 5 R⊕, planet occurrence scales linearly with metallicity Z. Extrapolating our results, we predict that short-period planets with Rp ≲ 2 R⊕ should be rare around early-M dwarf stars with [M/H] ≲ -0.5 or late-M dwarf stars with [M/H] ≲ +0.0. This dependence of planet occurrence on metallicity observed in the Kepler field emphasizes the need to control for metallicity in estimates of planet occurrence for late-type dwarf stars like those targeted by Kepler's K2 extension and the Transiting Exoplanet Survey Satellite. We confirm the theoretical expectation that the small-planet occurrence-host star metallicity relation is stronger for low-mass stars than for solar-type stars. We establish that the expected solid mass in planets around late-type dwarfs in the Kepler field is comparable to the total amount of planet-making solids in their protoplanetary disks. We argue that this high efficiency of planet formation favors planetesimal accretion over pebble accretion as the origin of the small planets observed by Kepler around late-type dwarf stars.

Keywords: Extrasolar rocky planets, Exoplanets, Planet hosting stars, Exoplanet formation, Extrasolar ice giants, Late-type dwarf stars
The Origin of Systems of Tightly Packed Inner Planets with Misaligned, Ultra-short-period Companions. Ultra-short-period planets provide a window into the inner edge of the parameter space occupied by planetary orbits. In one particularly intriguing class of multiplanet systems, the ultra-short-period planet is flanked by short-period companions, and the outer planets occupy a discernibly distinct dynamical state. In the observational database, this phenomenon is represented by a small number of stars hosting systems of tightly packed coplanar planets as well as an ultra-short-period planet, whose orbit is misaligned relative to the mutual plane of the former. In this work, we explore two different mechanisms that can produce an ultra-short-period planet that is misaligned with the rest of its compact planetary system: natural decoupling between the inner and outer system via the stellar quadrupole moment, and decoupling forced by an external companion with finely tuned orbital parameters. These two processes operate with different timescales, and can thus occur simultaneously. In this work, we use the K2-266 system as an illustrative example to elucidate the dynamics of these two processes, and highlight the types of constraints that may arise regarding the dynamical histories of systems hosting ultra-short-period planets.

Keywords: Exoplanet dynamics, Exoplanet evolution
KMT-2019-BLG-0842Lb: A Cold Planet below the Uranus/Sun Mass Ratio. We report the discovery of a cold planet with a very low planet/host mass ratio of q = (4.09 ± 0.27) × 10-5, which is similar to the ratio of Uranus/Sun (q = 4.37 × 10-5) in the solar system. The Bayesian estimates for the host mass, planet mass, system distance, and planet-host projected separation are Mhost = 0.76 ± 0.40M⊙, Mplanet = 10.3 ± 5.5M⊕, DL = 3.3 ± 1.3 kpc, and a⊥ = 3.3 ± 1.4 au, respectively. The consistency of the color and brightness expected from the estimated lens mass and distance with those of the blend suggests the possibility that the most blended light comes from the planet host, and this hypothesis can be established if high-resolution images are taken during the next (2020) bulge season. We discuss the importance of conducting optimized photometry and aggressive follow-up observations for moderately or very high magnification events to maximize the detection rate of planets with very low mass ratios.

Keywords: Gravitational microlensing, Gravitational microlensing exoplanet detection
Broadband Linear Polarization in the Region of the Open Star Cluster NGC 1817. Multiband linear polarimetric observations of 125 stars in the region of the cluster NGC 1817 have been carried out intending to study properties of interstellar dust and grains in that direction. The polarization is found to be wavelength-dependent, being maximum in the V band with an average value of 0.95%. The foreground interstellar dust grains appear to be the main source of linear polarization of starlight toward the direction of NGC 1817. The average value of the position angle in the V band of 119°2 is found to be less than the direction of the Galactic parallel in the region, indicating that the dust grains in the direction are probably not yet relaxed. Spatial distribution of dust appears to be more diverse in the coronal region than the core region of the cluster. The maximum value of the degree of polarization is estimated to be 0.93% for members of the cluster using the Serkowski relation. The average value of wavelength corresponding to the maximum polarization of 0.54 ± 0.02 μm indicates that the size distribution of dust grains in the line of sight is similar to that of the general interstellar medium. Several variable stars in the cluster were also observed polarimetrically and pulsating variables appear to have a slightly lower value of polarization from other nonvariable member stars of the cluster. There are indications of the existence of dust layers in front of those clusters which are located close to galactic plane while for clusters located away from galactic plane no major dust layers are observed.

Keywords: Interstellar dust, Interstellar dust extinction, Starlight polarization, Interstellar medium, Polarimeters, Open star clusters
A Perturbative Treatment of the Retrograde Co-orbital Motion. An important area of research in celestial mechanics is the analysis of dynamics in mean-motion resonances (MMR). In this paper, we consider a retrograde MMR 1:1 corresponding to a co-orbital motion, in which the asteroid and the planet revolve around the Sun in opposite directions. The motivation was provided by the recent discovery of real celestial bodies moving in such resonances with giant planets (the most famous example being 514107 Ka'epaoka'awela, a retrograde co-orbital asteroid of Jupiter). Our study is conducted in the context of a spatial restricted circular three-body problem. Applying double numerical averaging, we construct the equations describing the secular evolution of the asteroid's orbit and generate phase portraits in an e - ω space. In some cases, the averaging procedure is complicated by the coexistence of several modes of resonant motion. It leads to different scenarios of the long-term behavior and, consequently, to the splitting of the phase portrait into several sheets.

Keywords: Orbital motion, Asteroids, Orbital resonances, Celestial mechanics, Three-body problem, Perturbation methods
Nondetection of Helium in the Upper Atmospheres of Three Sub-Neptune Exoplanets. We present a search for helium in the upper atmospheres of three sub-Neptune-sized planets to investigate the origins of these ubiquitous objects. The detection of helium for a low-density planet would be strong evidence for the presence of a primary atmosphere accreted from the protoplanetary nebula because large amounts of helium are not expected in the secondary atmospheres of rocky planets. We used Keck+NIRSPEC to obtain high-resolution transit spectroscopy of the planets GJ 1214b, GJ 9827d, and HD 97658b around the 10833 Å He triplet feature. We did not detect helium absorption for any of the planets despite achieving a high level of sensitivity. We used the nondetections to set limits on the planets' thermosphere temperatures and atmospheric loss rates by comparing grids of 1D models to the data. We also performed coupled interior structure and atmospheric loss calculations, which suggest that the bulk atmospheres (winds) of the planets would be at most modestly enhanced (depleted) in helium relative to their primordial composition. Our lack of detections of the helium triplet for GJ 1214b and GJ 9827d is highly inconsistent with the predictions of models for the present-day mass loss on these planets. Higher signal-to-noise data would be needed to detect the helium feature predicted for HD 97658b. We identify uncertainties in the extreme-ultraviolet fluxes of the host stars and the lack of detailed mass-loss models specifically for cool and metal-enhanced atmospheres as the main limitations to the interpretation of our results. Ultimately, our results suggest that the upper atmospheres of sub-Neptune planets are fundamentally different from those of gas giant planets.

Keywords: Exoplanet atmospheric composition , Exoplanets, Super Earths, Mini Neptunes, Exoplanet atmospheres
A Mini-Neptune and a Radius Valley Planet Orbiting the Nearby M2 Dwarf TOI-1266 in Its Venus Zone: Validation with the Habitable-zone Planet Finder. We report on the validation of two planets orbiting the nearby (36 pc) M2 dwarf TOI-1266 observed by the TESS mission. This system is one of a few M dwarf multiplanet systems with close-in planets where the inner planet is substantially larger than the outer planet. The inner planet is sub-Neptune-sized (R = 2.46 ± 0.08 R⊕) with an orbital period of 10.9 days, while the outer planet has a radius of ${1.67}_{-0.11}^{+0.09}$ R⊕ and resides in the exoplanet radius valley—the transition region between rocky and gaseous planets. With an orbital period of 18.8 days, the outer planet receives an insolation flux of 2.4 times that of Earth, similar to the insolation of Venus. Using precision near-infrared radial velocities with the Habitable-zone Planet Finder Spectrograph, we place upper mass limits of 15.9 and 6.4 M⊕ at 95% confidence for the inner and outer planet, respectively. A more precise mass constraint of both planets, achievable with current radial velocity instruments given the host star brightness (V = 12.9, J = 9.7), will yield further insights into the dominant processes sculpting the exoplanet radius valley.

Keywords: Extrasolar rocky planets, Exoplanet detection methods, Exoplanets, Super Earths, Cold Neptunes, Mini Neptunes, Transit photometry
KELT-11 b: Abundances of Water and Constraints on Carbon-bearing Molecules from the Hubble Transmission Spectrum. In the past decade, the analysis of exoplanet atmospheric spectra has revealed the presence of water vapor in almost all the planets observed, with the exception of a fraction of overcast planets. Indeed, water vapor presents a large absorption signature in the wavelength coverage of the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3), which is the main space-based observatory for atmospheric studies of exoplanets, making its detection very robust. However, while carbon-bearing species such as methane, carbon monoxide, and carbon dioxide are also predicted from current chemical models, their direct detection and abundance characterization has remained a challenge. Here we analyze the transmission spectrum of the puffy, clear hot-Jupiter KELT-11 b from the HST WFC3 camera. We find that the spectrum is consistent with the presence of water vapor and an additional absorption at longer wavelengths than 1.5 μm, which could well be explained by a mix of carbon bearing molecules. CO2, when included is systematically detected. One of the main difficulties to constrain the abundance of those molecules is their weak signatures across the HST WFC3 wavelength coverage, particularly when compared to those of water. Through a comprehensive retrieval analysis, we attempt to explain the main degeneracies present in this data set and explore some of the recurrent challenges that are occurring in retrieval studies (e.g., the impact of model selection, the use of free versus self-consistent chemistry, and the combination of instrument observations). Our results make this planet an exceptional example of a chemical laboratory to test current physical and chemical models of the atmospheres of hot Jupiters.

Keywords: Exoplanet atmospheric composition , Bayesian statistics, Extrasolar gaseous giant planets, Exoplanet atmospheres
The End of Galaxy Surveys. For nearly a century, imaging and spectroscopic surveys of galaxies have given us information about the contents of the universe. We attempt to define the logical end point of such surveys by defining not the next galaxy survey but rather the final galaxy survey at near-infrared wavelengths; this would be the galaxy survey that exhausts the information content useful for addressing extant questions. Such a survey would require incredible advances in a number of technologies, and the survey details will depend on the as yet poorly constrained properties of the earliest galaxies. Using an exposure time calculator, we define nominal surveys for extracting the useful information for three science cases: dark energy cosmology, galaxy evolution, and supernovae (SN). We define scaling relations that trade off sky background, telescope aperture, and focal plane size to allow for a survey of a given depth over a given area. For optimistic assumptions, a 280 m telescope with a marginally resolved focal plane of 20 deg2 operating at L2 could potentially exhaust the cosmological information content of galaxies in a 10 yr survey. For galaxy evolution (making use of gravitational lensing to magnify the earliest galaxies) and SN, the same telescope would suffice. We discuss the technological advances needed to complete the last galaxy survey. While the final galaxy survey remains well outside of our technical reach today, we present scaling relations that show how we can progress toward the goal of exhausting the information content encoded in the shapes, positions, and colors of galaxies.

Keywords: Cosmology, Astronomical instrumentation, Galaxy evolution, Optical telescopes, Supernovae
High-contrast Thermal Infrared Spectroscopy with ALES: The 3-4 μm Spectrum of κ Andromedae b. We present the first L-band (2.8-4.1 μm) spectroscopy of κ Andromedae b, a ∼20 MJup companion orbiting at 1″ projected separation from its B9-type stellar host. We combine our Large Binocular Telescope (LBT) Arizona Lenslets for Exoplanet Spectroscopy (ALES) integral field spectrograph data with measurements from other instruments to analyze the atmosphere and physical characteristics of κ And b. We report a discrepancy of ∼20% (2σ) in the L' flux of κ And b when comparing to previously published values. We add an additional L' constraint using an unpublished imaging data set collected in 2013 using the LBT Interferometer/LMIRCam, the instrument in which the ALES module has been built. The LMIRCam measurement is consistent with the ALES measurement, both suggesting a fainter L-band scaling than previous studies. The data, assuming the flux scaling measured by ALES and LMIRCam imaging, are well fit by an L3-type brown dwarf. Atmospheric model fits to measurements spanning 0.9-4.8 μm reveal some tension with the predictions of evolutionary models, but the proper choice of cloud parameters can provide some relief. In particular, models with clouds extending to very low pressures composed of grains ≤1 μm appear to be necessary. If the brighter L' photometry is accurate, there is a hint that subsolar metallicity may be required.

Keywords: Exoplanet astronomy, Atmospheric composition, L dwarfs
High-resolution Near-infrared Spectroscopic Study of Galactic Supernova Remnants. I. Kinematic Distances. We have carried out high-resolution near-infrared spectroscopic observations toward 16 Galactic supernova remnants (SNRs) showing strong H2 emission features. A dozen bright H2 emission lines are clearly detected for individual SNRs, and we have measured their central velocities, line widths, and fluxes. For all SNRs except one (G9.9-0.8), the H2 line ratios are well consistent with that of thermal excitation at T ∼ 2000 K, indicating that the H2 emission lines are most likely from shock-excited gas and therefore that they are physically associated with the remnants. The kinematic distances to the 15 SNRs are derived from the central velocities of the H2 lines using a Galactic rotation model. We derive for the first time the kinematic distances to four SNRs: G13.5+0.2, G16.0-0.5, G32.1-0.9, and G33.2-0.6. Among the remaining 11 SNRs, the central velocities of the H2 emission lines for six SNRs are well consistent (±5 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ) with those obtained in previous radio observations, while for the other five SNRs (G18.1-0.1, G18.9-1.1, Kes 69, 3C 396, W49B) they are significantly different. We discuss the velocity discrepancies in these five SNRs. In G9.9-0.8, the H2 emission shows nonthermal line ratios and narrow line width (∼4 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), and we discuss its origin.

Keywords: High resolution spectroscopy, Interstellar line emission, Distance measure, Molecular clouds, Supernova remnants
Study of Star Clusters in the M83 Galaxy with a Convolutional Neural Network. We present a study of evolutionary and structural parameters of star cluster candidates in the spiral galaxy M83. For this we use a convolutional neural network trained on mock clusters and capable of fast identification and localization of star clusters, as well as inference of their parameters from multiband images. We use this pipeline to detect 3380 cluster candidates in Hubble Space Telescope observations. The sample of cluster candidates shows an age gradient across the galaxy's spiral arms, which is in good agreement with predictions of the density wave theory and other studies. As measured from the dust lanes of the spiral arms, the younger population of cluster candidates peaks at the distance of ∼0.4 kpc while the older candidates are more dispersed, but shifted toward ≳0.7 kpc in the leading part of the spiral arms. We find high-extinction cluster candidates positioned in the trailing part of the spiral arms, close to the dust lanes. We also find a large number of dense older clusters near the center of the galaxy and a slight increase of the typical cluster size further from the center.

Keywords: Convolutional neural networks, Galaxies, Star clusters
Modeling Stochastic Variability in Multiband Time-series Data. In preparation for the era of time-domain astronomy with upcoming large-scale surveys, we propose a state-space representation of a multivariate damped random walk process as a tool to analyze irregularly-spaced multifilter light curves with heteroscedastic measurement errors. We adopt a computationally efficient and scalable Kalman filtering approach to evaluate the likelihood function, leading to maximum $O({k}^{3}n)$ complexity, where k is the number of available bands and n is the number of unique observation times across the k bands. This is a significant computational advantage over a commonly used univariate Gaussian process that can stack up all multiband light curves in one vector with maximum $O({k}^{3}{n}^{3})$ complexity. Using such efficient likelihood computation, we provide both maximum likelihood estimates and Bayesian posterior samples of the model parameters. Three numerical illustrations are presented: (i) analyzing simulated five-band light curves for a comparison with independent single-band fits; (ii) analyzing five-band light curves of a quasar obtained from the Sloan Digital Sky Survey Stripe 82 to estimate short-term variability and timescale; (iii) analyzing gravitationally lensed g- and r-band light curves of Q0957+561 to infer the time delay. Two R packages, Rdrw and timedelay, are publicly available to fit the proposed models.

Keywords: Interdisciplinary astronomy, Astrostatistics, Astrostatistics tools
Optical Night Sky Brightness Measurements from the Stratosphere. This paper presents optical night sky brightness measurements from the stratosphere using CCD images taken with the Super-pressure Balloon-borne Imaging Telescope (SuperBIT). The data used for estimating the backgrounds were obtained during three commissioning flights in 2016, 2018, and 2019 at altitudes ranging from 28 to 34 km above sea level. For a valid comparison of the brightness measurements from the stratosphere with measurements from mountain-top ground-based observatories (taken at zenith on the darkest moonless night at high Galactic and high ecliptic latitudes), the stratospheric brightness levels were zodiacal light and diffuse Galactic light subtracted, and the airglow brightness was projected to zenith. The stratospheric brightness was measured around 5.5 hr, 3 hr, and 2 hr before the local sunrise time in 2016, 2018, and 2019, respectively. The B, V, R, and I brightness levels in 2016 were 2.7, 1.0, 1.1, and 0.6 mag arcsec-2 darker than the darkest ground-based measurements. The B, V, and R brightness levels in 2018 were 1.3, 1.0, and 1.3 mag arcsec-2 darker than the darkest ground-based measurements. The U and I brightness levels in 2019 were 0.1 mag arcsec-2 brighter than the darkest ground-based measurements, whereas the B and V brightness levels were 0.8 and 0.6 mag arcsec-2 darker than the darkest ground-based measurements. The lower sky brightness levels, stable photometry, and lower atmospheric absorption make stratospheric observations from a balloon-borne platform a unique tool for astronomy. We plan to continue this work in a future midlatitude long duration balloon flight with SuperBIT.

Keywords: CCD photometry, Night sky brightness, Diffuse radiation, Gegenschein, High altitude balloons, Sky brightness, Stratosphere, Optical observatories