Sazuna/UAT_keywords huggingface dataset:
Subaru Near-infrared Imaging Polarimetry of Misaligned Disks around the SR 24 Hierarchical Triple System. The SR 24 multistar system hosts both circumprimary and circumsecondary disks, which are strongly misaligned with each other. The circumsecondary disk is circumbinary in nature. Interestingly, both disks are interacting, and they possibly rotate in opposite directions. To investigate the nature of this unique twin disk system, we present 0.″1 resolution near-infrared polarized intensity images of the circumstellar structures around SR 24, obtained with HiCIAO mounted on the Subaru 8.2 m telescope. Both the circumprimary disk and the circumsecondary disk are resolved and have elongated features. While the position angle of the major axis and radius of the near-IR (NIR) polarization disk around SR 24S are 55° and 137 au, respectively, those around SR 24N are 110° and 34 au, respectively. With regard to overall morphology, the circumprimary disk around SR 24S shows strong asymmetry, whereas the circumsecondary disk around SR 24N shows relatively strong symmetry. Our NIR observations confirm the previous claim that the circumprimary and circumsecondary disks are misaligned from each other. Both the circumprimary and circumsecondary disks show similar structures in 12CO observations in terms of its size and elongation direction. This consistency is because both NIR and 12CO are tracing surface layers of the flared disks. As the radius of the polarization disk around SR 24N is roughly consistent with the size of the outer Roche lobe, it is natural to interpret the polarization disk around SR 24N as a circumbinary disk surrounding the SR 24Nb-Nc system. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Keywords: Polarimetry
ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of H<SUB>2</SUB>O, but No Evidence of Na or K. We present a new ground-based visual transmission spectrum of the hot Jupiter WASP-43b, obtained as part of the ACCESS Survey. The spectrum was derived from four transits observed between 2015 and 2018, with combined wavelength coverage between 5300 and 9000 Å and an average photometric precision of 708 ppm in 230 Å bins. We perform an atmospheric retrieval of our transmission spectrum combined with literature Hubble Space Telescope/WFC3 observations to search for the presence of clouds/hazes as well as Na, K, Hα, and H2O planetary absorption and stellar spot contamination over a combined spectral range of 5318-16420 Å. We do not detect a statistically significant presence of Na I or K I alkali lines, or Hα in the atmosphere of WASP-43b. We find that the observed transmission spectrum can be best explained by a combination of heterogeneities on the photosphere of the host star and a clear planetary atmosphere with H2O. This model yields a log evidence of 8.26 ± 0.42 higher than a flat (featureless) spectrum. In particular, the observations marginally favor the presence of large, low-contrast spots over the four ACCESS transit epochs with an average covering fraction {f}het}={0.27}-0.16+0.42 and temperature contrast ΔT = 132 K ± 132 K. Within the planet’s atmosphere, we recover a log H2O volume mixing ratio of -{2.78}-1.47+1.38, which is consistent with previous H2O abundance determinations for this planet.

Keywords: Observational astronomy, Exoplanets, Hot Jupiters, Stellar activity, Spectroscopy, Exoplanet atmospheres
The Two-sided Jet Structures of NGC 1052 at Scales from 300 to 4 × 10<SUP>7</SUP> Schwarzschild Radii. We investigated the jet width profile with distance along the jet in the nearby radio galaxy NGC 1052 at radial distances between ∼300 and 4 × 107 Schwarzschild radii (R S) from the central engine on both their approaching and receding jet sides. The width of jets was measured in images obtained with the Very Long Baseline Interferometry (VLBI) Space Observatory Programme, the Very Long Baseline Array, and the Very Large Array. The jet width profiles of receding jets are apparently consistent with those of approaching jets throughout the measuring distance ranges, indicating symmetry at least up to the sphere of gravitational influence of the central black hole. The power-law index a of the jet width profile (w jet ∝ r  a , where w jet is the jet width, r is the distance from the central engine in the unit of R S) apparently shows a transition from a ∼ 0 to a ∼ 1, i.e., the cylindrical-to-conical jet structures, at a distance of ∼1 × 104 R S. The cylindrical jet shape at small distances is reminiscent of the innermost jets in 3C 84. Both the central engines of NGC 1052 and 3C 84 are surrounded by dense material, part of which is ionized and causes heavy free-free absorption.

Keywords: Jets, Radio jets, Relativistic jets, Radio continuum emission, Radio galaxies, Active galactic nuclei, Fanaroff-Riley radio galaxies, Discrete radio sources
Binary Stars in Upper Scorpius. To address the statistics of binary stars in the 8 Myr old Upper Scorpius (USco) star formation region, we conducted a speckle interferometric survey of 614 association members more massive than 0.4 {{ \mathcal M }}☉  (spectral types earlier than M3V) based on the list of Luhman et al. (2018). We resolved 187 pairs, 55 of which are new discoveries. Also using the published data and the Gaia DR2, a catalog of 250 physical binaries was produced. We carefully estimated detection limits for each target and studied binary statistics in the separation range from 0.″06 to 20″ (9-2800 au), as well as clustering at larger separations. The frequency of companions with mass ratios q &gt; 0.3 in this separation range is 0.33 ± 0.04 and 0.35 ± 0.04 for early M- and solar-type stars, respectively, larger by 1.62 ± 0.22 and 1.39 ± 0.18 times compared to field stars of similar masses. The excess is produced mostly by pairs closer than 100 au. At separations from 100 to 104 au, the separation distribution and companion fraction resemble those of solar-type stars in the field. However, unlike in the field, we see a relative deficit of equal-mass binaries at separations of ∼500 au, compared to smaller and larger separations. The distribution of q depends on the separation, with a preference of larger q and a larger fraction of twins with q &gt; 0.95 at smaller separations. The binary population of USco differs from binaries in the field in several ways and suggests that binary statistics is not universal.

Keywords: Multiple stars, Star forming regions, Binary stars, Visual binary stars
An Information Theory Approach on Deciding Spectroscopic Follow-ups. Classification and characterization of variable phenomena and transient phenomena are critical for astrophysics and cosmology. These objects are commonly studied using photometric time series or spectroscopic data. Given that many ongoing and future surveys are conducted in a time domain, and given that adding spectra provides further insights but requires more observational resources, it would be valuable to know which objects we should prioritize to have a spectrum in addition to a time series. We propose a methodology in a probabilistic setting that determines a priori which objects are worth taking a spectrum of to obtain better insights, where we focus on the insight of the type of the object (classification). Objects for which we query their spectrum are reclassified using their full spectral information. We first train two classifiers, one that uses photometric data and another that uses photometric and spectroscopic data together. Then for each photometric object we estimate the probability of each possible spectrum outcome. We combine these models in various probabilistic frameworks (strategies), which are used to guide the selection of follow-up observations. The best strategy depends on the intended use, whether it is obtaining more confidence or accuracy. For a given number of candidate objects (127, equal to 5% of the data set) for taking spectra, we improve the class prediction accuracy by 37% as opposed to 20% of a non-naive (non-random) best-baseline strategy. Our approach provides a general framework for follow-up strategies and can be extended beyond classification to include other forms of follow-ups beyond spectroscopy.

Keywords: Computational methods, Astronomy data analysis, Variable stars, Astrostatistics tools
Physical Properties of the Star-forming Regions in the Interacting Galaxies NGC 3395/NGC 3396. We report long-slit spectroscopy of the early major merger galaxies NGC 3395/NGC 3396. The spectra are consistent with those for star-forming galaxies, but there is some indication of LINER-like active galactic nucleus activity in the center of NGC 3396. The total star formation rate in the regions observed is 2.83 M ⊙ yr-1, consistent with estimates for the entire galaxies. The highest abundances are in the centers of the galaxies, with the abundances decreasing with distance. There is a correlation between high abundance and high ionization parameter, both of which can be attributed to the presence of massive stars. Modeling with SB 99 indicates the star-forming regions are younger than 10 Myr. There are 1000-2000 WNL stars in the system, along with several thousand O stars, consistent with the ages of the star-forming regions. The highest electron densities are found in young regions with high star formation rates. The electron temperatures are higher than results for non-interacting galaxies, which is probably due to shock waves produced by the galaxy-galaxy interaction, the outflow of gas from massive stars, and/or collisions between gas clouds in the galaxies. There is star formation in the bridge of material between the galaxies. These regions are among the youngest in the system and have low abundances, suggesting the gas was pulled from the outer parts of the galaxies. X-ray point sources, probably high-mass X-ray binaries, are associated with several star-forming regions.

Keywords: Wolf-Rayet stars, Interacting galaxies
The Feasibility of Directly Imaging Nearby Cold Jovian Planets with MIRI/JWST. The upcoming launch of the James Webb Space Telescope (JWST) will dramatically increase our understanding of exoplanets, particularly through direct imaging. Microlensing and radial velocity surveys indicate that some M dwarfs host long-period giant planets. Some of these planets will likely be just a few parsecs away and a few astronomical units from their host stars, a parameter space that cannot be probed by existing high-contrast imagers. We studied whether the coronagraphs on the Mid-infrared Instrument on JWST can detect Jovian-type planets around nearby M dwarfs. For a sample of 27 very nearby M dwarfs, we simulated a sample of Saturn-Jupiter-mass planets with three atmospheric configurations and three orbital separations, observed in three different filters. We found that the f1550c 15.5 μm filter is best suited for detecting Jupiter-like planets. Jupiter-like planets with patchy cloud cover, 2 au from their star, are detectable at 15.5 μm around 14 stars in our sample, while Jupiters with clearer atmospheres are detectable around all stars in the sample. Saturns were most detectable at 10.65 and 11.4 μm (f1065c and f1140c filters), but only with cloud-free atmospheres and within 3 pc (six stars). Surveying all 27 stars would take &lt;170 hr of JWST integration time, or just a few hours for a shorter survey of the most favorable targets. There is one potentially detectable known planet in our sample: GJ 832 b. Observations aimed at detecting this planet should occur in 2024-2026, when the planet is maximally separated from the star.

Keywords: Exoplanets, Solar neighborhood, M stars, Infrared astronomy, Direct imaging, Extrasolar gaseous giant planets
SOAR TESS Survey. I. Sculpting of TESS Planetary Systems by Stellar Companions. The Transiting Exoplanet Survey Satellite (TESS) is finding transiting planet candidates around bright, nearby stars across the entire sky. The large field of view, however, results in low spatial resolution; therefore, multiple stars contribute to almost every TESS light curve. High angular resolution imaging can detect the previously unknown companions to planetary candidate hosts that dilute the transit depths, lead to host star ambiguity, and, in some cases, are the source of false-positive transit signals. We use speckle imaging on the Southern Astrophysical Research (SOAR) telescope to search for companions to 542 TESS planet candidate hosts in the southern sky. We provide correction factors for the 117 systems with resolved companions due to photometric contamination. The contamination in TESS due to close binaries is similar to that found in surveys of Kepler planet candidates. For the solar-type population, we find a deep deficit of close binary systems with projected stellar separations less than 100 au among planet candidate hosts (44 observed binaries compared to 124 expected based on field binary statistics). The close binary suppression among TESS planet candidate hosts is similar to that seen for the more distant Kepler population. We also find a large surplus of TESS planet candidates in wide binary systems detected in both SOAR and Gaia DR2 (119 observed binaries compared to 77 expected). These wide binaries almost exclusively host giant planets, however, suggesting that orbital migration caused by perturbations from the stellar companion may lead to planet-planet scattering and suppress the population of small planets in wide binaries. Both trends are also apparent in the M dwarf planet candidate hosts.

Keywords: Binary stars, Exoplanets, Close binary stars, Speckle interferometry, Exoplanet formation
Secular Eccentricity Oscillations in Axisymmetric Disks of Eccentric Orbits. Massive bodies undergo orbital eccentricity oscillations when embedded in an axisymmetric disk of smaller mass orbits. These eccentricity oscillations are driven by secular torques that seek to equalize the apsidal precession rates of all the orbits in the disk. We investigate this mechanism within the context of detached objects in the outer solar system, but we find that the oscillation timescale is too long for it to be dynamically important. It could however be interesting for phenomenon a bit farther from home, namely, feeding supermassive black holes and polluting the surfaces of white dwarf stars.

Keywords: Supermassive black holes, Kuiper belt, White dwarf stars, Solar system, Celestial mechanics, Trans-Neptunian objects
Variability in Proto-planetary Nebulae. VI. Multitelescope Light Curve Studies of Several Medium-bright (V = 13-15), Carbon-rich Objects. We present 10 years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F-G spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation periods of IRAS 04296+3429 (71 days), 06530-0213 (80 days), and 23304+6147 (84 days). A secondary period was found for each, with a period ratio P  2 /P  1  of 0.9. The light variations are small, 0.1-0.2 mag. These are similar to values found in other PPNe. The other two are found to be giant stars. IRAS 09296+1159 pulsates with a period of only 47 days but reaches pulsational light variations of 0.5 mag. Supplemental spectroscopy reveals the spectrum of a CH carbon star. IRAS 08359-1644 is a G1 III star that does not display pulsational variability; rather, it shows nonperiodic decreases of brightness of up to 0.5 mag over this 10 year interval. These drops in brightness are reminiscent of the light curves of R Corona Borealis variables, but with much smaller decreases in brightness and are likely due to transient dust obscuration. Its spectral energy distribution is very similar to that of the unusual oxygen-rich giant star HDE 233517, which possesses mid-infrared hydrocarbon emission features. These two non-PPNe turn out to be members of the rare group of giant stars with large mid-infrared excesses due to dust, objects which presumably have interesting evolutionary histories.

Keywords: Pulsating variable stars, Protoplanetary nebulae, Stellar pulsations, Carbon stars, Post-asymptotic giant branch, Red giant stars, Circumstellar dust
Covariance-regularized Reconstruction of Data Cubes in Integral Field Spectroscopy and Application to MaNGA Data. Integral field spectroscopy can map astronomical objects spatially and spectroscopically. Due to instrumental and atmospheric effects, it is common for integral field instruments to yield a sampling of the sky image that is both irregular and wavelength dependent. Most subsequent analysis procedures require a regular, wavelength-independent sampling (for example a fixed rectangular grid), and thus an initial step of fundamental importance is to resample the data onto a new grid. The best possible resampling would produce a well-sampled image, with a resolution equal to that imposed by the intrinsic spatial resolution of the instrument, telescope, and atmosphere, and with no statistical correlations between neighboring pixels. A standard method in the field to produce a regular set of samples from an irregular set of samples is Shepard’s method, but Shepard’s method typically yields images with a degraded resolution and large statistical correlations between pixels. Here we introduce a new method, which improves on Shepard’s method in both these respects. We apply this method to data from the Mapping Nearby Galaxies at Apache Point Observatory survey, part of Sloan Digital Sky Survey IV, demonstrating a full width at half maximum close to that of the intrinsic spatial resolution (and ∼16% better than Shepard’s method) and low statistical correlations between pixels. These results nearly achieve the ideal resampling. This method can have broader applications to other integral field data sets and to other astronomical data sets (such as dithered images) with irregular sampling.

Keywords: Observational astronomy, Astronomy data reduction, Galaxies, Spectroscopy
Exoplanet Imitators: A Test of Stellar Activity Behavior in Radial Velocity Signals. Accurately modeling effects from stellar activity is a key step in detecting radial velocity (RV) signals of low-mass and long-period exoplanets. RVs from stellar activity are dominated by magnetic active regions that move in and out of sight as the star rotates, producing signals with timescales related to the stellar rotation period. Methods to characterize RV periodograms assume that peaks from magnetic active regions will typically occur at the stellar rotation period or a related harmonic. However, with surface features unevenly spaced and evolving over time, signals from magnetic activity are not perfectly periodic, and the effectiveness of characterizing them with sine curves is unconfirmed. With a series of simulations, we perform the first test of common assumptions about signals from magnetic active regions in RV periodograms. We simulate RVs with quasi-periodic signals that account for evolution and migration of magnetic surface features. As test cases, we apply our analysis to two exoplanet hosts, Kepler-20 and K2-131. Simulating observing schedules and uncertainties of real RV surveys, we find that magnetic active regions commonly produce maximum periodogram peaks at spurious periods unrelated to the stellar rotation period: 81% and 72% of peaks, respectively, for K2-131 and Kepler-20. These unexpected peaks can potentially lead to inaccuracies in derived planet masses. We also find that these spurious peaks can sometimes survive multiple seasons of observation, imitating signals typically attributed to exoplanet companions.

Keywords: Stellar activity
Absolute Properties of the Eclipsing γ Dor Star V404 Lyrae. We present the first high-resolution spectra for the eclipsing binary V404 Lyr showing γ Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of T eff,1 = 7330 ± 150 K and a rotational velocity of v 1 sin i = 148 ± 18 km s-1. The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted Kepler data gives us accurate stellar and system parameters of V404 Lyr. The masses, radii, and luminosities are M 1 = 2.17 ± 0.06 M ⊙, R 1 = 1.91 ± 0.02 R ⊙, and L 1 = 9.4 ± 0.8 L ⊙ for the primary, and M 2 = 1.42 ± 0.04 M ⊙, R 2 = 1.79 ± 0.02 R ⊙, and L 2 = 2.9 ± 0.2 L ⊙ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of M 3b  = 0.71 ± 0.15 M ⊙ in an orbit of P 3b  = 642 ± 3 days, e 3b  = 0.21 ± 0.04, and a 3b  = 509 ± 2 R ⊙. The third light of l 3 = 4.1% ± 0.2% could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipse-subtracted light residuals, we detected 45 frequencies with signal-to-noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies (f 1 - f 6, f 9), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a γ Dor-type variable star.

Keywords: Fundamental parameters of stars, Multi-periodic pulsation, Spectroscopy, Eclipsing binary stars, Stellar oscillations, Asteroseismology
Asteroid Discovery and Light Curve Extraction Using the Hough Transform: A Rotation Period Study for Subkilometer Main-belt Asteroids. The intranight trajectories of asteroids can be approximated by straight lines, and so are their intranight detections. Therefore, the Hough transform, a line detecting algorithm, can be used to connect the line-up detections to find asteroids. We applied this algorithm to a high-cadence Pan-STARRS 1 (PS1) observation, which was originally designed to collect asteroid light curves for rotation period measurements. The algorithm recovered most of the known asteroids in the observing fields and, moreover, discovered 3574 new asteroids with magnitude mainly of 21.5 &lt; w  p1 &lt; 22.5 mag. This magnitude range is equivalent to subkilometer main-belt asteroids (MBAs), which usually lack rotation period measurements due to their faintness. Using the light curves of the 3574 new asteroids, we obtained 122 reliable rotation periods, of which 13 are super-fast rotators (SRFs; i.e., rotation period of &lt;2 hr). The required cohesion to survive these SFRs range from tens to thousands of Pa, a value consistent with the known SFRs and the regolith on the Moon and Mars. The higher chance of discovering SFRs here suggests that subkilometer MBAs probably harbor more SFRs.

Keywords: Period determination, Asteroids, Surveys, Light curves, Main belt asteroids, Astronomical methods
New Horizons Observations of an Ultraviolet Stellar Occultation and Appulse by Pluto’s Atmosphere. A few hours after its encounter with Pluto, the Alice UV instrument on the New Horizons spacecraft observed the simultaneous stellar occultation and appulse of two UV-bright stars, HD 43153 and HD 42545, respectively. As during the solar occultation that occurred immediately prior, the transmission of starlight through Pluto’s atmosphere was sensitive to absorption by N2, CH4, C2H6, C2H2, C2H4, and haze. The line of sight to each star passed over different areas of Pluto from those probed by the solar occultation, providing insight into the degree of spatial and diurnal variability of atmospheric composition on Pluto. In this work, we report the profile of CH4 derived from both the stellar occultation and appulse observation, as well as the profiles of C2H6, C2H2, C2H4, and haze for the stellar occultation only. We compare these profiles to the solar occultation results and discuss implications for atmospheric variability on Pluto.

Keywords: Occultation, Ultraviolet extinction, Pluto