Sazuna/UAT_keywords huggingface dataset:
The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 Dwarfs with UKIRT. We present parallaxes, proper motions, and J-band photometry for 348 L and T dwarfs measured using the wide-field near-infrared camera WFCAM on the United Kingdom Infrared Telescope. This is the largest single batch of infrared parallaxes for brown dwarfs to date. Our parallaxes have a median uncertainty of 3.5 mas, similar to most previous ground-based infrared parallax surveys. Our target list was designed to complete a volume-limited parallax sample of L0-T8 dwarfs out to 25 pc spanning declinations -30° to +60° (68% of the sky). We report the first parallaxes for 165 objects, and we improve on previous measurements for another 53 objects. Our targets include 104 objects (mostly early-L dwarfs) having Gaia DR2 parallax measurements with which our parallaxes are consistent. We include an extensive comparison of previous literature parallaxes for L and T dwarfs with both our results and Gaia DR2 measurements, identifying systematic offsets for some previous surveys. Our parallaxes confirm that 14 objects previously identified as wide common proper motion companions to main-sequence stars have distances consistent with companionship. We also report new ${J}_{\mathrm{MKO}}$ photometry for our targets, including the first measurements for 193 of our targets and improvements over previously published ${J}_{\mathrm{MKO}}$ photometry for another 60 targets. Altogether, our parallaxes will enable the first population studies using a volume-limited sample spanning spectral types L0-T8 defined entirely by parallaxes.

Keywords: Trigonometric parallax, Parallax, L dwarfs, Proper motions, Late-type dwarf stars, Infrared photometry, T dwarfs
Photometric Redshifts with the LSST. II. The Impact of Near-infrared and Near-ultraviolet Photometry. Accurate photometric redshift (photo-z) estimates are essential to the cosmological science goals of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). In this work, we use simulated photometry for mock galaxy catalogs to explore how LSST photo-z estimates can be improved by the addition of near-infrared (NIR) and/or ultraviolet (UV) photometry from the Euclid, Wide-Field InfrarRed Survey Telescope (WFIRST), and/or Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR) space telescopes. Generally, we find that deeper optical photometry can reduce the standard deviation of the photo-z estimates more than adding NIR or UV filters but that additional filters are the only way to significantly lower the fraction of galaxies with catastrophically under- or overestimated photo-z. For Euclid, we find that the addition of JH 5σ photometric detections can reduce the standard deviation for galaxies with z &gt; 1 (z &gt; 0.3) by ∼20% (∼10%), and the fraction of outliers by ∼40% (∼25%). For WFIRST, we show how the addition of deep YJHK photometry could reduce the standard deviation by ≳50% at z &gt; 1.5 and drastically reduce the fraction of outliers to just ∼2% overall. For CASTOR, we find that the addition of its UV- and u-band photometry could reduce the standard deviation by ∼30% and the fraction of outliers by ∼50% for galaxies with z &lt; 0.5. We also evaluate the photo-z results within sky areas that overlap with both the NIR and UV surveys and when spectroscopic training sets built from the surveys' small-area deep fields are used.

Keywords: Cosmology, Galaxy photometry, Multi-color photometry, Sky surveys
Dust Reverberation of 3C 273: Torus Structure and Lag-Luminosity Relation. We monitored the z = 0.158 quasar 3C 273 between 2015 and 2019 in the optical (BVrz) and near-infrared (JHK) with the aim to perform dust reverberation mapping. Accounting for host galaxy and accretion disk contributions, we obtained pure dust light curves in JHK. Cross correlations between the V band and the dust light curves yield an average rest-frame delay for the hot dust of τcent ∼ 410 days. This is a factor of two shorter than that expected from the the dust ring radius Rx ∼ 900 lt-day reported from interferometric studies. The dust covering factor (CF) is about 8%, much smaller than that predicted from the half covering angle of 45° found for active galactic nuclei (AGNs). We analyze the asymmetric shape of the correlation functions and explore whether an inclined biconical bowl-shaped dust torus geometry could bring these findings (τcent, Rx and CF) into a consistent picture. The hot varying dust emission originates from the edge of the bowl rim with a small covering angle 40° &lt; θ &lt; 45°, and we see only the near side of the biconus. Such a dust gloriole with Rx = 900 ± 200 lt-day and an inclination 12° matches the data remarkably well. Comparing the results of 3C 273 with literature for less luminous AGN, we find a lag-luminosity relation τ ∝ Lα with α = 0.33-0.40, flatter than the widely adopted relation with α ∼ 0.5. We address several explanations for the new lag-luminosity relation.

Keywords: Reverberation mapping, Active galactic nuclei, Photometry, Quasars
Orbital Stability of Exomoons and Submoons with Applications to Kepler 1625b-I. An intriguing question in the context of dynamics arises: could a moon possess a moon itself? Such a configuration does not exist in the solar system, although this may be possible in theory. Kollmeier &amp; Raymond determined the critical size of a satellite necessary to host a long-lived subsatellite, or submoon. However, the orbital constraints for these submoons to exist are still undetermined. Domingos et al. indicated that moons are stable out to a fraction of the host planet's Hill radius RH,p, which in turn depend on the eccentricity of its host's orbit. Motivated by this, we simulate systems of exomoons and submoons for 105 planetary orbits, while considering many initial orbital phases to obtain the critical semimajor axis in terms of RH,p or the host satellite's Hill radius RH,sat, respectively. We find that, assuming circular coplanar orbits, the stability limit for an exomoon is 0.40 RH,p and for a submoon is 0.33 RH,sat. Additionally, we discuss the observational feasibility of detecting these subsatellites through photometric, radial velocity, or direct imaging observations using the Neptune-sized exomoon candidate Kepler 1625b-I and identify how stability can shape the identification of future candidates.

Keywords: Exoplanet dynamics, Orbits, Natural satellites (Extrasolar), Exoplanets
A Wide-orbit Exoplanet OGLE-2012-BLG-0838Lb. We present the discovery of a planet on a very wide orbit in the microlensing event OGLE-2012-BLG-0838. The signal of the planet is well separated from the main peak of the event and the planet-star projected separation is found to be twice the Einstein ring radius, which corresponds to a projected separation of ≍4 au. Similar planets around low-mass stars are very hard to find using any technique other than microlensing. We discuss microlensing model fitting in detail and discuss the prospects for measuring the mass and distance of the lens system directly.

Keywords: Exoplanet detection methods, Gravitational lensing shear, Extrasolar ice giants
A Free-floating or Wide-orbit Planet in the Microlensing Event OGLE-2019-BLG-0551. High-cadence observations of the Galactic bulge by the microlensing surveys led to the discovery of a handful of extremely short-timescale microlensing events that can be attributed to free-floating or wide-orbit planets. Here, we report the discovery of another strong free-floating planet candidate, which was found from the analysis of the gravitational microlensing event OGLE-2019-BLG-0551. The light curve of the event is characterized by a very short duration (≲3 days) and a very small amplitude (≲0.1 mag). From modeling of the light curve, we find that the Einstein timescale, ${t}_{{\rm{E}}}=0.381\pm 0.017$ day, is much shorter, and the angular Einstein radius, ${\theta }_{{\rm{E}}}=4.35\pm 0.34$ μas, is much smaller than those of typical lensing events produced by stellar-mass lenses ( ${t}_{{\rm{E}}}\sim 20$ days, ${\theta }_{{\rm{E}}}\sim 0.3$ mas), indicating that the lens is very likely to be a planetary-mass object. We conduct an extensive search for possible signatures of a companion star in the light curve of the event, finding no significant evidence for the putative host star. For the first time, we also demonstrate that the angular Einstein radius of the lens does not depend on blending in the low-magnification events with strong finite source effects.

Keywords: Gravitational microlensing, Free floating planets, Gravitational microlensing exoplanet detection, Finite-source photometric effect
Keck/NIRC2 L'-band Imaging of Jovian-mass Accreting Protoplanets around PDS 70. We present L'-band imaging of the PDS 70 planetary system with Keck/NIRC2 using the new infrared pyramid wave front sensor. We detected both PDS 70 b and c in our images, as well as the front rim of the circumstellar disk. After subtracting off a model of the disk, we measured the astrometry and photometry of both planets. Placing priors based on the dynamics of the system, we estimated PDS 70 b to have a semimajor axis of ${20}_{-4}^{+3}$ au and PDS 70 c to have a semimajor axis of ${34}_{-6}^{+12}$ au (95% credible interval). We fit the spectral energy distribution (SED) of both planets. For PDS 70 b, we were able to place better constraints on the red half of its SED than previous studies and inferred the radius of the photosphere to be 2-3 RJup. The SED of PDS 70 c is less well constrained, with a range of total luminosities spanning an order of magnitude. With our inferred radii and luminosities, we used evolutionary models of accreting protoplanets to derive a mass of PDS 70 b between 2 and 4 MJup and a mean mass accretion rate between 3 × 10-7 and 8 × 10-7 MJup/yr. For PDS 70 c, we computed a mass between 1 and 3 MJup and mean mass accretion rate between 1 × 10-7 and 5 × 10-7 MJup/yr. The mass accretion rates imply dust accretion timescales short enough to hide strong molecular absorption features in both planets' SEDs.

Keywords: Exoplanet dynamics, Coronagraphic imaging, Exoplanet formation, Orbit determination, Exoplanet atmospheres
Determination of Size, Albedo, and Thermal Inertia of 10 Vesta Family Asteroids with WISE/NEOWISE Observations. In this work, we investigate the size, thermal inertia, surface roughness, and geometric albedo of 10 Vesta family asteroids using the Advanced Thermophysical Model, based on the thermal-infrared data acquired by mainly NASA's Wide-field Infrared Survey Explorer. Here, we show that the average thermal inertia and geometric albedo of the investigated Vesta family members are 42 J m-2 s-1/2 K-1 and 0.314, respectively, where the derived effective diameters are less than 10 km. Moreover, the family members have a relatively low roughness fraction on their surfaces. The similarity in thermal inertia and geometric albedo among the V-type Vesta family members may reveal their close connection in origin and evolution. As the fragments of the cratering event of Vesta, the family members may have undergone a similar evolutionary process, thereby leading to very close thermal properties. Finally, we estimate their regolith grain sizes with different volume filling factors.

Keywords: Main belt asteroids
Nearby Quintuple Systems κ Tucanae and ξ Scorpii. Architecture and parameters of two wide, nearby hierarchical systems containing five solar-type stars each, κ Tuc and ξ Sco, are studied. Using Gaia astrometry and photometry, masses are determined from visual orbits and isochrones, and effective temperatures from spectra or colors. Both systems are ∼2 Gyr old. Their spatial motion corresponds to a young disk but does not match any known kinematic group. Internal proper motions relative to the center of mass and radial velocities show that wide ∼8 kau outer pairs are bound. No correlation between orbit orientations in the inner subsystems is observed. All masses except one are confined to the narrow range from 0.8 to 1.5 solar. Strongly correlated masses and wide orbits can be explained if those systems formed by fragmentation in relative isolation and their components accreted gas from a common source, as expected in a hierarchical collapse. Young moving groups could be formed in similar environments, and many of them contain high-order hierarchies.

Keywords: Wide binary stars, Multiple stars, Visual binary stars, Star formation
Speckle Interferometry of Nearby Multiple Stars: 2007-2019 Positional Measurements and Orbits of Eight Objects. The orbits of eight systems with low-mass components (HIP 14524, HIP 16025, HIP 28671, HIP 46199, HIP 47791, HIP 60444, HIP 61100, and HIP 73085) are presented. Speckle interferometric data were obtained at the 6 m Big Telescope Alt-azimuth Special Astrophysical Observatory of the Russian Academy of Sciences (BTA SAO RAS) from 2007 to 2019. New data, together with measures already in the literature, made it possible to improve upon previous orbital solutions in six cases and to construct orbits for the first time in the two remaining cases (HIP 14524 and HIP 60444). Mass sums are obtained using both Hipparcos and Gaia parallaxes, and a comparison with previously published values is made. Using the Worley &amp; Heintz criteria, the classification of the orbits constructed is carried out.

Keywords: Binary stars, Orbital elements, Stellar masses, Fundamental parameters of stars, Orbits, Spectroscopic binary stars, Low mass stars, Speckle interferometry, Interferometric binary stars
HATS-71b: A Giant Planet Transiting an M3 Dwarf Star in TESS Sector 1. We report the discovery of HATS-71b, a transiting gas giant planet on a $P=3.7955$ day orbit around a $G=15.35$ mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during transits is 4.7%, more than in any other confirmed transiting planet system. The planet was identified as a candidate by the ground-based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA Transiting Exoplanet Survey Satellite mission (TIC 234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of $1.024\pm 0.018$ ${R}_{{\rm{J}}}$ and mass of $0.37\,\pm 0.24$ ${M}_{{\rm{J}}}$ (95% confidence upper limit of $\lt 0.80$ ${M}_{{\rm{J}}}$ ), while the star has a mass of $0.4861\pm 0.0060$ ${M}_{\odot }$ and a radius of $0.4783\pm 0.0060$ ${R}_{\odot }$ .

Keywords: Observational astronomy, Exoplanets, Radial velocity, Astronomical instrumentation, Exoplanet detection methods, Transit photometry
Bayesian Approach for Determining Microlens System Properties with High-angular-resolution Follow-up Imaging. We present the details of the Bayesian analysis of the planetary microlensing event MOA-2016-BLG-227, whose excess flux is likely due to a source/lens companion or an unrelated ambient star, as well as of the assumed prior distributions. Furthermore, we apply this method to four reported planetary events, MOA-2008-BLG-310, MOA-2011-BLG-293, OGLE-2012-BLG-0527, and OGLE-2012-BLG-0950, where adaptive optics observations have detected excess flux at the source star positions. For events with small angular Einstein radii, our lens mass estimates are more uncertain than those of previous analyses, which assumed that the excess was due to the lens. Our predictions for MOA-2008-BLG-310 and OGLE-2012-BLG-0950 are consistent with recent results on these events obtained via Keck and Hubble Space Telescope observations when the source star is resolvable from the lens star. For events with small angular Einstein radii, we find that it is generally difficult to conclude whether the excess flux comes from the host star. Therefore, it is necessary to identify the lens star by measuring its proper motion relative to the source star to determine whether the excess flux comes from the lens star. Even without such measurements, our method can be used to statistically test the dependence of the planet-hosting probability on the stellar mass.

Keywords: Gravitational microlensing, Exoplanet detection methods, Gravitational microlensing exoplanet detection, High-resolution microlensing event imaging
Galaxy Cluster Contribution to the Diffuse Extragalactic Ultraviolet Background. The diffuse ultraviolet background radiation has been mapped over most of the sky with 2' resolution using data from the Galaxy Evolution Explorer survey. We utilize this map to study the correlation between the UV background and clusters of galaxies discovered via the Sunyaev-Zeldovich effect in the Planck survey. We use only high Galactic latitude ( $| b| \gt 60^\circ $ ) galaxy clusters to avoid contamination by Galactic foregrounds, and we only analyze clusters with a measured redshift. This leaves us with a sample of 142 clusters over the redshift range of 0.02 ≤ z ≤ 0.72, which we further subdivide into four redshift bins. In analyzing our stacked samples binned by redshift, we find evidence for a central excess of UV background light compared to local backgrounds for clusters with z &lt; 0.3. We then stacked these z &lt; 0.3 clusters to find a statistically significant excess of 12 ± 2.3 photon cm-2 s-1 sr-1 Å-1 over the median of ∼380 photon cm-2 s-1 sr-1 Å-1 measured around random blank fields. We measure the stacked radial profile of these clusters, and find that the excess UV radiation decays to the level of the background at a radius of ∼1 Mpc, roughly consistent with the maximum radial extent of the clusters. Analysis of possible physical processes contributing to the excess UV brightness indicates that non-thermal emission from relativistic electrons in the intracluster medium and faint, unresolved UV emission from cluster member galaxies and intracluster light are likely the dominant contributors.

Keywords: Galaxy clusters, Ultraviolet astronomy, Cosmic background radiation
The Bulge Radial Velocity Assay for RR Lyrae Stars (BRAVA-RR) DR2: A Bimodal Bulge?. The radial velocities of 2768 fundamental-mode RR Lyrae stars (RRLs) toward the southern Galactic bulge are presented, spanning the southern bulge from -8° &lt; l &lt; + 8° and -3° &lt; b &lt; -6°. Distances derived from the pulsation properties of the RRLs are combined with Gaia proper motions to give constraints on the orbital motions of 1389 RRLs. The majority (∼75%) of the bulge RRLs have orbits consistent with these stars being permanently bound to &lt;3.5 kpc from the Galactic Center, similar to the bar. However, unlike the bulge giants, the RRLs exhibit slower rotation and a higher velocity dispersion. The higher velocity dispersion arises almost exclusively from halo interlopers passing through the inner Galaxy. We present 82 stars with space velocities ≳500 km s-1 and find that the majority of these high-velocity stars are halo interlopers; it is unclear if a subsample of these stars with similar space velocities has a common origin. Once the 25% of the sample represented by halo interlopers is cleaned, we can clearly discern two populations of bulge RRLs in the inner Galaxy. The first population of RRLs is not as tightly bound to the Galaxy (but is still confined to the inner ∼3.5 kpc) and is both spatially and kinematically consistent with the barred bulge. The second population is more centrally concentrated and does not trace the bar. One possible interpretation is that this population was born prior to bar formation, as their spatial location, kinematics, and pulsation properties suggest, possibly from an accretion event at high redshift.

Keywords: Milky Way formation, Stellar populations, Stellar kinematics, Galactic bulge, RR Lyrae variable stars, Galaxy radial velocities, Halo stars
Photometry as a Proxy for Stellar Activity in Radial Velocity Analyses. Stellar activity remains a limiting factor in measuring precise planet parameters from radial velocity spectroscopy, not least in the search for Earth-mass planets orbiting in the habitable zones of Sun-like stars. One approach to mitigate stellar activity is to use combined analyses of both radial velocity and time-series photometry. We present an analysis of simultaneous disk-integrated photometry and radial velocity data of the Sun in order to determine the useful limits of a combined analysis. We find that simple periodogram or autocorrelation analysis of solar photometry give the correct rotation period &lt;50% of the time. We therefore use a Gaussian process to investigate the time variability of solar photometry and to directly compare simultaneous photometry with radial velocity data. We find that the hyperparameter posteriors are relatively stable over 70 yr of solar photometry and the amplitude tracks the solar cycle. We observe good agreement between the hyperparameter posteriors for the simultaneous photometry and radial velocity data. Our primary conclusion is a recommendation to include an additional prior in Gaussian process fits to constrain the evolutionary timescale to be greater than the recurrence timescale (i.e., the rotation period) to recover more physically plausible and useful results. Our results indicate that such simultaneous monitoring may be a useful tool in enhancing the precision of radial velocity surveys.

Keywords: Solar activity, Radial velocity, Stellar activity
Hubble Space Telescope Astrometry in the Orion Nebula Cluster: Census of Low-mass Runaways. We present a catalog of high-precision proper motions in the Orion Nebula Cluster (ONC), based on Treasury Program observations with the Hubble Space Telescope's (HST) ACS/WFC camera. Our catalog contains 2454 objects in the magnitude range of 14.2 &lt; mF775W &lt; 24.7, thus probing the stellar masses of the ONC from ∼0.4 M⊙ down to ∼0.02 M⊙ over an area of ∼550 arcmin2. We provide a number of internal velocity dispersion estimates for the ONC that indicate a weak dependence on stellar location and mass. There is good agreement with the published velocity dispersion estimates, although nearly all of them (including ours at ${\sigma }_{v,x}=0.94$ and ${\sigma }_{v,y}=1.25$ mas yr-1) might be biased by the overlapping young stellar populations of Orion A. We identified four new ONC candidate runaways based on HST and the Gaia DR 2 data, all with masses less than ∼1 M⊙. The total census of known candidate runaway sources is 10—one of the largest samples ever found in any Milky Way open star cluster. Surprisingly, none of them have tangential velocities exceeding 20 km s-1. If most of them indeed originated in the ONC, it may compel the re-examination of dynamical processes in very young star clusters. It appears that the mass function of the ONC is not significantly affected by the lost runaways.

Keywords: Hubble Space Telescope, Young star clusters, Stellar dynamics, Low mass stars, Space astrometry, Proper motions, Runaway stars