Sazuna/UAT_keywords huggingface dataset:
Double Image Polarimeter—Ultra Fast: Simultaneous Three-color (BV R) Polarimeter with Electron-multiplying Charge-coupled Devices. We describe a new instrument capable of high-precision (10-5) polarimetric observations simultaneously in three passbands (BVR). The instrument utilizes electron-multiplying charge-coupled device (EM CCD) cameras for high efficiency and fast image readout. The key features of the Double Image Polarimeter—Ultra Fast (DIPol-UF) are: (i) the optical design with high throughput and inherent stability; (ii) great versatility, which makes the instrument optimally suitable for observations of bright and faint targets; and (iii) a control system, which allows the use of the polarimeter remotely. Examples are given of the first results obtained from high signal-to-noise observations of bright nearby stars and of fainter sources such as X-ray binaries in their quiescent states.

Keywords: Observational astronomy, Binary stars, Black holes, High energy astrophysics, Polarimeters, Photometer, Polarimetry
Identifying Bound Stellar Companions to Kepler Exoplanet Host Stars Using Speckle Imaging. The Kepler mission and subsequent ground-based follow-up observations have revealed a number of exoplanet host stars with nearby stellar companions. This study presents speckle observations of 57 Kepler objects of interest (KOIs) that are also double stars, each observed over a 3-8 yr period, which has allowed us to track their relative motions with high precision. Measuring the position angle and separation of the companion with respect to the primary can help determine if the pair exhibits common proper motion, indicating it is likely to be a bound binary system. We report on the motions of 34 KOIs that have close stellar companions, three of which are triple stars, for a total of 37 companions studied. Eighteen of the 34 systems are confirmed exoplanet hosts, including one triple star, while four other systems have been subsequently judged to be false positives and twelve are yet to be confirmed as planet hosts. We find that 21 are most likely to be common proper motion pairs, 4 are line-of-sight companions, and 12 are of an uncertain disposition at present. The fraction of the confirmed exoplanet host systems that are common proper motion pairs is approximately 86% in this sample. In this subsample, the planets are exclusively found with periods of less than 110 days, so that in all cases the stellar companion is found at a much larger separation from the planet host star than the planet itself. A preliminary period-radius relation for the confirmed planets in our sample suggests no obvious differences at this stage with the full sample of known exoplanets.

Keywords: Astrometry, Speckle interferometry, Interferometric binary stars, Visual binary stars, Planet hosting stars
First Detection of Orbital Motion for HD 106906 b: A Wide-separation Exoplanet on a Planet Nine-like Orbit. HD 106906 is a 15 Myr old short-period (49 days) spectroscopic binary that hosts a wide-separation (737 au) planetary-mass ( $\sim 11\,{M}_{\mathrm{Jup}}$ ) common proper motion companion, HD 106906 b. Additionally, a circumbinary debris disk is resolved at optical and near-infrared wavelengths that exhibits a significant asymmetry at wide separations that may be driven by gravitational perturbations from the planet. In this study we present the first detection of orbital motion of HD 106906 b using Hubble Space Telescope images spanning a 14 yr period. We achieve high astrometric precision by cross-registering the locations of background stars with the Gaia astrometric catalog, providing the subpixel location of HD 106906 that is either saturated or obscured by coronagraphic optical elements. We measure a statistically significant 31.8 ± 7.0 mas eastward motion of the planet between the two most constraining measurements taken in 2004 and 2017. This motion enables a measurement of the inclination between the orbit of the planet and the inner debris disk of either ${36}_{-14}^{+27}$ deg or ${44}_{-14}^{+27}$ deg, depending on the true orientation of the orbit of the planet. There is a strong negative correlation between periastron and mutual inclination; orbits with smaller periastra are more misaligned with the disk plane. With a periastron of ${510}_{-320}^{+480}$ au, HD 106906 b is likely detached from the planetary region within 100 au radius, showing that a Planet Nine-like architecture can be established very early in the evolution of a planetary system.

Keywords: Exoplanets, Astrometry, Orbit determination, Debris disks, Extrasolar gaseous giant planets
TOI 540 b: A Planet Smaller than Earth Orbiting a Nearby Rapidly Rotating Low-mass Star. We present the discovery of TOI 540 b, a hot planet slightly smaller than Earth orbiting the low-mass star 2MASS J05051443-4756154. The planet has an orbital period of P = 1.239149 days (±170 ms) and a radius of $r=0.903\pm 0.052{R}_{\oplus }$ , and is likely terrestrial based on the observed mass-radius distribution of small exoplanets at similar insolations. The star is 14.008 pc away and we estimate its mass and radius to be $M=0.159\pm 0.014$ ${M}_{\odot }$ and $R=0.1895\pm 0.0079{R}_{\odot }$ , respectively. The star is distinctive in its very short rotational period of ${P}_{\mathrm{rot}}=17.4264\pm 0.0094$ hr and correspondingly small Rossby number of 0.007 as well as its high X-ray-to-bolometric luminosity ratio of ${L}_{{\rm{X}}}/{L}_{\mathrm{bol}}=0.0028$ based on a serendipitous XMM-Newton detection during a slew operation. This is consistent with the X-ray emission being observed at a maximum value of ${L}_{{\rm{X}}}/{L}_{\mathrm{bol}}\simeq {10}^{-3}$ as predicted for the most rapidly rotating M dwarfs. TOI 540 b may be an alluring target to study atmospheric erosion due to the strong stellar X-ray emission. It is also among the most accessible targets for transmission and emission spectroscopy and eclipse photometry with the James Webb Space Telescope, and may permit Doppler tomography with high-resolution spectroscopy during transit. This discovery is based on precise photometric data from the Transiting Exoplanet Survey Satellite and ground-based follow-up observations by the MEarth team.

Keywords: Extrasolar rocky planets, Transit photometry, Stellar rotation, Exoplanets
Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates. We present TRICERATOPS, a new Bayesian tool that can be used to vet and validate TESS Objects of Interest (TOIs). We test the tool on 68 TOIs that have been previously confirmed as planets or rejected as astrophysical false positives. By looking in the false-positive probability (FPP)-nearby false-positive probability (NFPP) plane, we define criteria that TOIs must meet to be classified as validated planets (FPP &lt; 0.015 and NFPP &lt; 10-3), likely planets (FPP &lt; 0.5 and NFPP &lt; 10-3), and likely nearby false positives (NFPP &gt; 10-1). We apply this procedure on 384 unclassified TOIs and statistically validate 12, classify 125 as likely planets, and classify 52 as likely nearby false positives. Of the 12 statistically validated planets, 9 are newly validated. TRICERATOPS is currently the only TESS vetting and validation tool that models transits from nearby contaminant stars in addition to the target star. We therefore encourage use of this tool to prioritize follow-up observations that confirm bona fide planets and identify false positives originating from nearby stars.

Keywords: Exoplanet astronomy, Exoplanets, Astrostatistics, Planet hosting stars
On the Estimation of Circumbinary Orbital Properties. We describe a fast, approximate method to characterize the orbits of satellites around a central binary in numerical simulations. A goal is to distinguish the free eccentricity—the random motion of a satellite relative to a dynamically cool orbit—from oscillatory modes driven by the central binary's time-varying gravitational potential. We assess the performance of the method using the Kepler-16, Kepler-47, and Pluto-Charon systems. We then apply the method to a simulation of orbital damping in a circumbinary environment, resolving relative speeds between small bodies that are slow enough to promote mergers and growth. These results illustrate how dynamical cooling can set the stage for the formation of Tatooine-like planets around stellar binaries and the small moons around the Pluto-Charon binary planet.

Keywords: Exoplanet dynamics, Orbital elements, Natural satellite formation, Exoplanet formation, Exoplanet evolution, Orbital theory, Pluto, N-body simulations
EXPRES. II. Searching for Planets around Active Stars: A Case Study of HD 101501. By controlling instrumental errors to below 10 cm s-1, the EXtreme PREcision Spectrograph (EXPRES) allows for a more insightful study of photospheric velocities that can mask weak Keplerian signals. Gaussian processes (GP) have become a standard tool for modeling correlated noise in radial velocity data sets. While GPs are constrained and motivated by physical properties of the star, in some cases they are still flexible enough to absorb unresolved Keplerian signals. We apply GP regression to EXPRES radial velocity measurements of the 3.5 Gyr old chromospherically active Sun-like star, HD 101501. We obtain tight constraints on the stellar rotation period and the evolution of spot distributions using 28 seasons of ground-based photometry, as well as recent Transiting Exoplanet Survey Satellite data. Light-curve inversion was carried out on both photometry data sets to reveal the spot distribution and spot evolution timescales on the star. We find that the &gt;5 m s-1 rms radial velocity variations in HD 101501 are well modeled with a GP stellar activity model without planets, yielding a residual rms scatter of 45 cm s-1. We carry out simulations, injecting and recovering signals with the GP framework, to demonstrate that high-cadence observations are required to use GPs most efficiently to detect low-mass planets around active stars like HD 101501. Sparse sampling prevents GPs from learning the correlated noise structure and can allow it to absorb prospective Keplerian signals. We quantify the moderate to high-cadence monitoring that provides the necessary information to disentangle photospheric features using GPs and to detect planets around active stars.

Keywords: Exoplanet detection methods, Radial velocity, Gaussian Processes regression
KIC 10975348: A Double-mode or Triple-mode High-amplitude δ Scuti Star?. In this paper, we analyze the light variations of KIC 10975348 using photometric data delivered from the Kepler mission. This star is exceptionally faint (Kp = 18.6 mag) compared to most well-studied δ Scuti stars. The Fourier analysis of the short-cadence data (i.e., Q14, Q15, and Q16, spanning 220 days) reveals that the variations are dominated by the strongest mode with a frequency of F0 = 10.231899 day-1, which is compatible with that obtained from RATS-Kepler. The other two independent modes with F1 (=13.4988 day-1) and F2 (=19.0002 day-1) are newly detected and have amplitudes two orders of magnitude smaller than F0. We note that, for the first time, this star is identified to be a high-amplitude δ Sct (HADS) star with an amplitude of about 0.7 mag, and the lower ratio of F0/F1 = 0.758 suggests that it might be a metal-rich variable star. The frequency F2 may be a third overtone mode, suggesting that this target might be a new radial triple-mode HADS star. We perform an O - C analysis using 1018 newly determined times of maximum light and derive an ephemeris formula of Tmax = 2456170.241912(0)+0.097734(1) × E. The O - C diagram shows that the pulsation period of KIC 10975348 seems to show no obvious change, which is in contrast to that of the majority of HADS stars. The possible cause of that may be due to the current short time span of the observations. To verify its possible period variations, regular observation from space with a longer time span in the future is needed.

Keywords: Short period variable stars, Stellar oscillations, Delta Scuti variable stars
ELT Imaging of MWC 297 from the 23 m LBTI: Complex Disk Structure and a Companion Candidate. Herbig Ae/Be stars represent the early outcomes of star formation and the initial stages of planet formation at intermediate stellar masses. Understanding both of these processes requires detailed characterization of their disk structures and companion frequencies. We present new 3.7 μm imaging of the Herbig Be star MWC 297 from nonredundant masking observations on the phase-controlled, 23 m Large Binocular Telescope Interferometer. The images reveal complex disk structure on the scales of several au, as well as a companion candidate. We discuss physical interpretations for these features and demonstrate that the imaging results are independent of choices such as priors, regularization hyperparameters, and error-bar estimates. With an angular resolution of ∼17 mas, these data provide the first robust Extremely Large Telescope-resolution view of a distant young star.

Keywords: Herbig Ae/Be stars, Direct imaging, Circumstellar matter, Interferometry
A Method to Extract Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission from Spitzer Spectra: Application to M51. The mid-infrared spectrum contains rich diagnostics to probe the physical properties of galaxies, among which the pervasive emission features from polycyclic aromatic hydrocarbons (PAHs) offer promising means of estimating the star formation rate (SFR) relatively immune from dust extinction. This paper investigates the effectiveness of PAH emission as a SFR indicator on subkiloparsec scales by studying the Spitzer/IRS mapping-mode observations of the nearby grand-design spiral galaxy M51. We present a new approach of analyzing the spatial elements of the spectral data cube that simultaneously maximizes spatial resolution and spatial coverage, while yielding reliable measurements of the total, integrated 5-20 μm PAH emission. We devise a strategy of extracting robust PAH emission using spectra with only partial spectral coverage, complementing missing spectral regions with properly combined mid-infrared photometry. We find that in M51 the PAH emission correlates tightly with the extinction-corrected far-ultraviolet, near-ultraviolet, and Hα emission, from scales of ∼0.4 kpc close to the nucleus to 6 kpc out in the disk of the galaxy, indicating that PAH serves as an excellent tracer of SFR over a wide range of galactic environments. But regional differences exist. Close to the active nucleus of M51 the 6.2 μm feature is weaker, and the overall level of PAH emission is suppressed. The spiral arms and the central star-forming region of the galaxy emit stronger 7.7 and 8.6 μm PAH features than the inter-arm regions.

Keywords: Interstellar molecules, Star forming regions, Interstellar emissions, Star formation, Active galactic nuclei, Interstellar medium, Interstellar extinction
PoPE: A Population-based Approach to Model the Spatial Structure of Astronomical Systems. We present a novel population-based Bayesian inference approach to model the average and population variance of the spatial distribution of a set of observables from ensemble analysis of low signal-to-noise-ratio measurements. The method consists of (1) inferring the average profile using Gaussian processes and (2) computing the covariance of the profile observables given a set of independent variables. Our model is computationally efficient and capable of inferring average profiles of a large population size from noisy measurements, without stacking data or parameterizing the shape of the mean profile. We demonstrate the performance of our method using dark matter, gas, and stellar profiles extracted from hydrodynamical cosmological simulations of galaxy formation. POPULATION PROFILE ESTIMATOR is publicly available in a GitHub repository. Our new method should be useful for measuring the spatial distribution and internal structure of a variety of astrophysical systems using large astronomical surveys.

Keywords: Open source software, Astronomy data modeling, Spatial point processes, Astronomy data analysis, Astrostatistics
Eccentricity Driven Climate Effects in the Kepler-1649 System. The discovery of terrestrial exoplanets is uncovering increasingly diverse architectures. Of particular interest are those systems that contain exoplanets at a variety of star-planet separations, allowing direct comparison of exoplanet evolution (comparative planetology). The Kepler-1649 system contains two terrestrial planets similar both in size and insolation flux to Venus and Earth, although their eccentricities remain largely unconstrained. Here we present results of dynamical studies of the system and the potential effects on climate. The eccentricities of the Kepler-1649 system are poorly constrained, and we show that there are dynamically viable regions for further terrestrial planets in between the two known planets for a limited range of eccentricities. We investigate the effect of eccentricity of the outer planet on the dynamics of both planets and show that this results in high-frequency (1000-3000 years) eccentricity oscillations in long-term stable configurations. We calculate the resulting effect of these eccentricity variations on insolation flux and present the results of 3D climate simulations for the habitable zone planet. Our simulations demonstrate that, despite large eccentricity variations, the planet can maintain stable climates with relatively small temperature variations on the substellar hemisphere for a variety of initial climate configurations. Such systems thus provide key opportunities to explore alternative Venus/Earth climate evolution scenarios.

Keywords: Exoplanet dynamics, Exoplanet atmospheres, Habitable planets, Exoplanets
β Cephei Pulsations in the High-mass Eclipsing System CW Cephei. CW Cep is an early B-type eclipsing binary with mass measurement precisions better than 1%. We report the discovery of pulsation signatures in the Transiting Exoplanet Survey Satellite time-series data of the system observed during Sectors 17 and 18. Our binary modeling indicates that the target star is a partially eclipsing detached system with masses of 12.95 M⊙ and 11.88 M⊙ and radii of 5.52 R⊙ and 5.09 R⊙ in an eccentric orbit of e = 0.0305. The distance to the eclipsing system, 928 ± 36 pc, is much more precise than the Gaia distance of 962 ± 453 pc. Applying multifrequency analyses to the residual light curve in the outside-eclipse part, we detected 13 significant signals in two frequency regions. Six frequencies below 1 day-1 appeared to be mostly orbital harmonic and combination terms, or sidelobes due to insufficient removal of the binary effects. In contrast, seven frequencies clustered around 2.73 day-1 and 5.34 day-1 could be considered β Cep-type pulsations. Our results represent the second discovery of β Cep pulsations present in double-lined eclipsing binaries with precise masses and, hence, CW Cep serves as an important test bed for the asteroseismic modeling of high-mass stars.

Keywords: Fundamental parameters of stars, Beta Cephei variable stars, Multi-periodic pulsation, Eclipsing binary stars, Stellar oscillations, Asteroseismology
On the Diversity of Asymmetries in Gapped Protoplanetary Disks. Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum caused by dust trapping in pressure bumps and potentially vortices or horseshoes. The origin of the asymmetries and their diversity remains unclear. We present a comprehensive study of 16 disks for which the gas surface density profile has been constrained by CO isotopologue data. First, we compare the azimuthal extents of the dust continuum profiles with the local gas surface density in each disk and find that the asymmetries correspond to higher Stokes numbers or low gas surface density. We discuss which asymmetric structures can be explained by a horseshoe, a vortex, or spiral density waves. Second, we reassess the gas gap radii from the 13CO maps, which are about a factor of 2 smaller than the dust ring radii, suggesting that the companions in these disks are in the brown dwarf (∼15-50 MJup) or super-Jovian (∼3-15 MJup) mass regime on eccentric orbits. This is consistent with the estimates from contrast curves on companion mass limits. These curves rule out (sub)stellar companions (q &gt; 0.05) for the majority of the sample at the gap location, but it remains possible at even smaller radii. Third, we find that spiral arms in scattered-light images are primarily detected around high-luminosity stars with disks with wide gaps, which can be understood by the dependence of the spiral arm pitch angle on disk temperature and companion mass.

Keywords: Protoplanetary disks, Planet formation, Circumstellar disks
Evolution of the Quiescent Disk Surrounding a Superoutburst of the Dwarf Nova TW Virginis. In this paper, we investigate portions of the Kepler K2 Short Cadence light curve of the dwarf nova (DN) TW Vir at quiescence, using light-curve modeling. The light curve was separated into 24 sections, each with a data length of ∼0.93 days, comprising 4 sections before, and 20 after a superoutburst (SO). Due to morphological differences, the quiescent orbital modulation is classified into three types. Using a fixed disk radius and the two component stellar parameters, all 24 synthetic disk models from these sections show a consistent configuration, consisting of a disk and two hotspots: one at the vertical side of the edge of the disk and the other on the surface of the disk. Before the SO, the disk and a ringlike surface-hotspot are suddenly enhanced, triggering a precursor, and then the SO. At the end of the quiescent period following the SO and before the first normal outburst, the edge-hotspot becomes hotter, while the surface-hotspot switches into a "coolspot" with a coverage of nearly half of the disk's surface. During quiescence, the surface-hotspot is always located at the outer part of the disk, with a constant radial width. A flat radial temperature distribution of the disk is found, and appears flatter when approaching the outburst. Like many U Gem-type DN with orbital periods of 3-5 hr, the mass transfer rate is significantly lower than the predictions of the standard/revised models of CV evolution.

Keywords: Accretion, White dwarf stars, Light curves, U Geminorum stars, Interacting binary stars, Dwarf novae, Cataclysmic variable stars
The Investigation of Seven Kepler Contact Binaries in the Field of NGC 6819. Using the Kepler Eclipsing Binary Catalog, we found seven EW-type eclipsing binaries within the tidal radius of the intermediate-aged open cluster NGC 6819 (about 40'). These seven EW eclipsing binaries are all confirmed to be contact binaries by light curve analysis with the 2015 version Wilson-Devinney program. Using the parameter characteristics of contact binaries, we found that only KIC 4937217 could be a member of NGC 6819. Moreover, KIC 5199489 should be a shallow, unity-mass-ratio contact binary implying an early contact stage or a mass-ratio reverse stage. Nevertheless, KIC 5198934 and KIC 5374883 should be deep, low mass ratio contact binaries (DLMRCBs), which are usually considered as premergers.

Keywords: Eclipsing binary stars, Open star clusters, Binary stars, Contact binary stars