Sazuna/UAT_keywords huggingface dataset:
Revisiting MOA 2013-BLG-220L: A Solar-type Star with a Cold Super-Jupiter Companion. We present the analysis of high-resolution images of MOA-2013-BLG-220, taken with the Keck adaptive optics system six years after the initial observation, identifying the lens as a solar-type star hosting a super-Jupiter-mass planet. The masses of planets and host stars discovered by microlensing are often not determined from light-curve data, while the star-planet mass ratio and projected separation in units of Einstein ring radius are well measured. High-resolution follow-up observations after the lensing event is complete can resolve the source and lens. This allows direct measurements of flux, and the amplitude and direction of proper motion, giving strong constraints on the system parameters. Due to the high relative proper motion, ${{\boldsymbol{\mu }}}_{\mathrm{rel},\mathrm{Geo}}=12.62\pm 0.11$ mas yr-1, the source and lens were resolved in 2019, with a separation of 77.1 ± 0.5 mas. Thus, we constrain the lens flux to ${K}_{\mathrm{Keck},\mathrm{lens}}=17.92\pm 0.02$ . By combining constraints from the model and Keck flux, we find the lens mass to be ${M}_{L}=0.88\pm 0.05\ {M}_{\odot }$ at ${D}_{L}=6.72\pm 0.59\,\mathrm{kpc}$ . With a mass ratio of $q=(3.00\pm 0.03)\times {10}^{-3}$ the planet's mass is determined to be ${M}_{{\rm{P}}}=2.74\pm 0.17\ {M}_{{\rm{J}}}$ at a separation of ${r}_{\perp }=3.03\pm 0.27\,\mathrm{au}$ . The lens mass is much higher than the prediction made by Bayesian analysis that assumes all stars have an equal probability to host a planet of the measured mass ratio, and suggests that planets with mass ratios of a few times 10-3 are more common orbiting massive stars. This demonstrates the importance of high-resolution follow-up observations for testing theories like these.

Keywords: Gravitational microlensing, Proper motions, Exoplanets
Self-consistent Color-Stellar Mass-to-light Ratio Relations for Low Surface Brightness Galaxies. The color-stellar mass-to-light ratio relation (CMLR) is a widely accepted tool for estimating the stellar mass (M*) of a galaxy. However, an individual CMLR tends to give distinct M* for a same galaxy when it is applied in different bands. Examining five representative CMLRs from the literature, we find that the difference in M* predicted in different bands from optical to near-infrared by a CMLR is 0.1 ∼ 0.3 dex. Based on a sample of low surface brightness galaxies that covers a wide range of color and luminosity, we therefore recalibrated each original CMLR in r, i, z, J, H, and K bands to give internally self-consistent M* for a same galaxy. The g-r is the primary color indicator in the recalibrated relations, which show little dependence on red (r-z) or near-infrared (J-K) colors. Additionally, the external discrepancies in the originally predicted γ* by the five independent CMLRs have been greatly reduced after recalibration, especially in the near-infrared bands, implying that the near-infrared luminosities are more robust in predicting γ*. For each CMLR, the recalibrated relations provided in this work could produce internally self-consistent M* from divergent photometric bands, and are extensions of the recalibrations from the Johnson-Cousin filter system by the pioneering work of McGaugh &amp; Schombert to the filter system of the Sloan Digital Sky Survey.

Keywords: Galaxy properties, Galaxy stellar content, Scaling relations, Photometry, Low surface brightness galaxies
Predictions of the Nancy Grace Roman Space Telescope Galactic Exoplanet Survey. II. Free-floating Planet Detection Rates. The Nancy Grace Roman Space Telescope (Roman) will perform a Galactic Exoplanet Survey (RGES) to discover bound exoplanets with semimajor axes greater than 1 au using gravitational microlensing. Roman will even be sensitive to planetary-mass objects that are not gravitationally bound to any host star. Such free-floating planetary-mass objects (FFPs) will be detected as isolated microlensing events with timescales shorter than a few days. A measurement of the abundance and mass function of FFPs is a powerful diagnostic of the formation and evolution of planetary systems, as well as the physics of the formation of isolated objects via direct collapse. We show that Roman will be sensitive to FFP lenses that have masses from that of Mars (0.1 M⊕) to gas giants (M ≳ 100 M⊕) as isolated lensing events with timescales from a few hours to several tens of days, respectively. We investigate the impact of the detection criteria on the survey, especially in the presence of finite-source effects for low-mass lenses. The number of detections will depend on the abundance of such FFPs as a function of mass, which is at present poorly constrained. Assuming that FFPs follow the fiducial mass function of cold, bound planets adapted from Cassan et al., we estimate that Roman will detect ∼250 FFPs with masses down to that of Mars (including ∼60 with masses ≤ M⊕). We also predict that Roman will improve the upper limits on FFP populations by at least an order of magnitude compared to currently existing constraints. * During the preparation of this manuscript, the name of the Wide Field Infrared Survey Telescope was changed to the Nancy Grace Roman Space Telescope.

Keywords: Gravitational microlensing, Free floating planets, Space telescopes, Exoplanet detection methods
Revised and New Proper Motions for Confirmed and Candidate Milky Way Dwarf Galaxies. A new derivation of systemic proper motions of Milky Way satellites is presented and applied to 59 confirmed or candidate dwarf galaxy satellites using Gaia Data Release 2. This constitutes all known Milky Way dwarf galaxies (and likely candidates) as of 2020 May, except for the Magellanic Clouds, the Canis Major and Hydra 1 stellar overdensities, and the tidally disrupting Bootes III and Sagittarius dwarf galaxies. We derive systemic proper motions for the first time for Indus 1, DES J0225+0304, Cetus 2, Pictor 2, and Leo T, but note that the latter three rely on photometry that is of poorer quality than that of the rest of the sample. We cannot resolve a signal for Bootes 4, Cetus 3, Indus 2, Pegasus 3, or Virgo 1. Our method is inspired by the maximum likelihood approach of Pace &amp; Li and examines simultaneously the spatial, color-magnitude, and proper motion distribution of sources. Systemic proper motions are derived without the need to identify confirmed radial velocity members, although the proper motions of these stars, where available, are incorporated into the analysis through a prior on the model. The associated uncertainties on the systemic proper motions are on average a factor of ∼1.4 smaller than existing literature values. Analysis of the implied membership distribution of the satellites suggests that we accurately identify member stars with a contamination rate lower than 1 in 20.

Keywords: Local Group, Milky Way stellar halo, Dwarf galaxies, Proper motions
A Mystery in Chamaeleon: Serendipitous Discovery of a Galactic Symbiotic Nova. We present the serendipitous discovery of a low optical-luminosity nova occurring in a D-type symbiotic binary star system in the Milky Way. We lay out the extensive archival data alongside new follow-up observations related to the stellar object CN Cha in the constellation of Chamaeleon. The object had long period (250 days), high amplitude (3 mag) optical variability in its recent past, preceding an increase in optical brightness by 8 magnitudes and a persistence at this brightness for about 3 yr, followed by a period of 1.4 mag yr-1 dimming. The object's current optical luminosity seems to be dominated by Hα emission, which also exhibits blueshifted absorption (a P-Cygni-like profile). After consideration of a number of theories to explain these myriad observations, we determine that CN Cha is most likely a symbiotic (an evolved-star-white-dwarf binary) system that has undergone a long-duration, low optical brightness, nova, placing it squarely in the class of so-called "slow novae," of which there are only a few known examples. The duration of the optical plateau in CN Cha would make it the shortest timescale plateau of any known slow symbiotic novae.

Keywords: Symbiotic binary stars, Interacting binary stars, Synodic period, Novae
TYCHO: Realistically Simulating Exoplanets within Stellar Clusters. I. Improving the Monte Carlo Approach. To fully understand the diverse population of exoplanets, we must study their early lives within open clusters, the birthplace of most stars with masses &gt;0.5M⊙ (including those currently in the field). Indeed, when we observe planets within clustered environments, we notice highly eccentric and odd systems that suggest the importance of dynamical pathways created by interactions with additional bodies (as in the case of HD 285507b). However, it has proven difficult to investigate these effects, as many current numerical solvers for the multi-scale N-body problem are simplified and limited in scope. To remedy this, we aim to create a physically complete computational solution to explore the role of stellar close encounters and interplanetary interactions in producing the observed exoplanet populations for both open cluster stars and field stars. We present a new code, TYCHO, which employs a variety of different computational techniques, including multiple N-body integration methods, close encounter handling, modified Monte Carlo scattering experiments, and a variety of empirically informed initial conditions. We discuss the methodology in detail, and its implementation within the AMUSE software framework. Approximately 1% of our systems are promptly disrupted by star-star encounters contributing to the rogue planets occurrence rate. Additionally, we find that close encounters which that perturb long-period planets lead to 38.3% of solar-system-like planetary systems becoming long-term unstable.

Keywords: Exoplanet dynamics, Interstellar dynamics, Exoplanet systems, Computational methods, Open star clusters
Clarissa Family Age from the Yarkovsky Effect Chronology. The Clarissa family is a small collisional family composed of primitive C-type asteroids. It is located in a dynamically stable zone of the inner asteroid belt. In this work we determine the formation age of the Clarissa family by modeling planetary perturbations as well as thermal drift of family members due to the Yarkovsky effect. Simulations were carried out using the SWIFT-RMVS4 integrator modified to account for the Yarkovsky and Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effects. We ran multiple simulations starting with different ejection velocity fields of fragments, varying proportion of initially retrograde spins, and also tested different Yarkovsky/YORP models. Our goal was to match the observed orbital structure of the Clarissa family which is notably asymmetrical in the proper semimajor axis, ap. The best fits were obtained with the initial ejection velocities ≲20 m s-1 of diameter D ≃ 2 km fragments, ∼4:1 preference for spin-up by YORP, and assuming that ≃80% of small family members initially had retrograde rotation. The age of the Clarissa family was found to be tage = 56 ± 6 Myr for the assumed asteroid density ρ = 1.5 g cm-3. Small variation of density to smaller or larger value would lead to slightly younger or older age estimates. This is the first case where the Yarkovsky effect chronology has been successfully applied to an asteroid family younger than 100 Myr.

Keywords: Main belt asteroids, Minimum chi-squared, Orbital resonances, N-body simulations
Evolution of an Asteroid Family under YORP, Yarkovsky, and Collisions. Any population of asteroids, like asteroid families, will disperse in semimajor axis due to the Yarkovsky effect. The amount of drift is modulated by the asteroid spin state evolution, which determines the balance between the diurnal and seasonal Yarkovsky forces. The asteroid's spin state is, in turn, controlled in part by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. The otherwise smooth evolution of an asteroid can be abruptly altered by collisions, which can cause impulsive changes in the spin state and can move the asteroid onto a different YORP track. In addition, collisions may also alter the YORP parameters by changing the superficial features and overall shape of the asteroid. Thus, the coupling between YORP and Yarkovsky is also strongly affected by the impact history of each body. To investigate this coupling, we developed a statistical code modeling the time evolution of semimajor axis under YORP-Yarkovsky coupling. It includes the contributions of NYORP (normal YORP), TYORP (tangential YORP), and collisions whose effects are deterministically calculated and not added in a statistical way. We find that both collisions and TYORP increase the dispersion of a family in semimajor axis by making the spin axis evolution less smooth and regular. We show that the evolution of a family's structure with time is complex and collisions randomize the YORP evolution. In our test families, we do not observe the formation of a "YORP-eye" in the semimajor axis versus diameter distribution, even after a long period of time. If present, the "YORP-eye" might be a relic of an initial ejection velocity pattern of the collisional fragments.

Keywords: Main belt asteroids, Asteroids
Transits of Known Planets Orbiting a Naked-eye Star. Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD 136352 (Nu2 Lupi) is a naked-eye (V = 5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1 days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD 136352 system, revealing radii of ${1.482}_{-0.056}^{+0.058}$ R⊕ and ${2.608}_{-0.077}^{+0.078}$ R⊕ for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of ${\rho }_{b}={7.8}_{-1.1}^{+1.2}$ g cm-3 and ${\rho }_{c}={3.50}_{-0.36}^{+0.41}$ g cm-3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.

Keywords: Exoplanets, Exoplanet structure, Radial velocity, Transit photometry, Exoplanet atmospheres
Near-infrared Spectral Characterization of Solar-type Stars in the Northern Hemisphere. Although solar-analog stars have been studied extensively over the past few decades, most of these studies have focused on visible wavelengths, especially those identifying solar-analog stars to be used as calibration tools for observations. As a result, there is a dearth of well-characterized solar analogs for observations in the near-infrared, a wavelength range important for studying solar system objects. We present 184 stars selected based on solar-like spectral type and V-J and V-K colors whose spectra we have observed in the 0.8-4.2 μm range for calibrating our asteroid observations. Each star has been classified into one of three ranks based on spectral resemblance to vetted solar analogs. Of our set of 184 stars, we report 145 as reliable solar-analog stars, 21 as solar analogs usable after spectral corrections with low-order polynomial fitting, and 18 as unsuitable for use as calibration standards owing to spectral shape, variability, or features at low to medium resolution. We conclude that all but five of our candidates are reliable solar analogs in the longer wavelength range from 2.5 to 4.2 μm. The average colors of the stars classified as reliable or usable solar analogs are V-J = 1.148, V-H = 1.418, and V-K = 1.491, with the entire set being distributed fairly uniformly in R.A. across the sky between -27° and +67° in decl.

Keywords: Standard stars, Solar analogs
Detecting Exoplanets Using Eclipsing Binaries as Natural Starshades. We investigate directly imaging exoplanets around eclipsing binaries using the eclipse as a natural tool for dimming the binary and thus increasing the planet to star brightness contrast. At eclipse, the binary becomes pointlike, making coronagraphy possible. We select binaries where the planet-star contrast would be boosted by &gt;10× during eclipse, making it possible to detect a planet that is ≳10× fainter or in a star system that is ∼2-3× more massive than otherwise. Our approach will yield insights into planet occurrence rates around binaries versus individual stars. We consider both self-luminous (SL) and reflected light (RL) planets. In the SL case, we select binaries whose age is young enough so that an orbiting SL planet would remain luminous; in U Cep and AC Sct, respectively, our method is sensitive to SL planets of ∼4.5 and ∼9 MJ with current ground- or near-future space-based instruments and ∼1.5 and ∼6 MJ with future ground-based observatories. In the RL case, there are three nearby (≲50 pc) systems—V1412 Aql, RR Cae, and RT Pic—around which a Jupiter-like planet at a planet-star separation of ≳20 mas might be imaged with future ground- and space-based coronagraphs. A Venus-like planet at the same distance might be detectable around RR Cae and RT Pic. A habitable Earth-like planet represents a challenge; while the planet-star contrast at eclipse and planet flux are accessible with a 6-8 m space telescope, the planet-star separation is 1/3-1/4 of the angular separation limit of modern coronagraphy.

Keywords: Eclipsing binary stars, Coronagraphic imaging, Direct imaging, Exoplanets
Infrared Observations of 2I/Borisov near Perihelion. As the first interstellar comet, 2I/Borisov provides a unique opportunity to study the surface composition of a comet from another stellar system, particularly whether it has water ice. In order to investigate the nature of 2I/Borisov, we conducted infrared observations close to perihelion. The water ice, if present, is expected to be revealed by absorption features at 1.5 and 2 micron. We therefore used FLAMINGOS-2 mounted on the Gemini south telescope, to carry out deep imaging on 2019 November 30 UT and spectroscopy on 2019 December 7 UT. At first glance, our imaging did not reveal an apparent coma or a cometary tail. This is due to the bright sky background and our short exposure times. Nevertheless we were able to put an upper limit of the size of the nucleus, as well as provide high-precision astrometry that can be used to investigate nongravitational acceleration in the future. Our infrared spectra showed a negative slope, contrary to the results by Yang et al. It is not unheard of for a comet to show a negative slope, and to progressively exhibit a spectrum with decreasing slope. Possible causes of the decreasing slope are an increase in water ice and/or decrease in dust size. Given the fact that our observations were carried out close to perihelion, it is likely that both factors contribute to the decreasing, negative slope of the infrared spectrum.

Keywords: Comets
TOI 694b and TIC 220568520b: Two Low-mass Companions near the Hydrogen-burning Mass Limit Orbiting Sun-like Stars. We report the discovery of TOI 694 b and TIC 220568520 b, two low-mass stellar companions in eccentric orbits around metal-rich Sun-like stars, first detected by the Transiting Exoplanet Survey Satellite (TESS). TOI 694 b has an orbital period of 48.05131 ± 0.00019 days and eccentricity of 0.51946 ± 0.00081, and we derive a mass of 89.0 ± 5.3 ${M}_{\mathrm{Jup}}$ (0.0849 ± 0.0051 ${M}_{\odot }$) and radius of 1.111 ± 0.017 ${R}_{\mathrm{Jup}}$ (0.1142 ± 0.0017 ${R}_{\odot }$). TIC 220568520 b has an orbital period of 18.55769 ± 0.00039 days and eccentricity of 0.0964 ± 0.0032, and we derive a mass of 107.2 ± 5.2 ${M}_{\mathrm{Jup}}$ (0.1023 ± 0.0050 ${M}_{\odot }$) and radius of 1.248 ± 0.018 ${R}_{\mathrm{Jup}}$ (0.1282 ± 0.0019 ${R}_{\odot }$). Both binary companions lie close to and above the hydrogen-burning mass threshold that separates brown dwarfs and the lowest-mass stars, with TOI 694 b being 2σ above the canonical mass threshold of 0.075 ${M}_{\odot }$. The relatively long periods of the systems mean that the magnetic fields of the low-mass companions are not expected to inhibit convection and inflate the radius, which according to one leading theory is common in similar objects residing in short-period tidally synchronized binary systems. Indeed we do not find radius inflation for these two objects when compared to theoretical isochrones. These two new objects add to the short but growing list of low-mass stars with well-measured masses and radii, and highlight the potential of the TESS mission for detecting such rare objects orbiting bright stars.

Keywords: M dwarf stars, Eclipsing binary stars, Low mass stars
Anisotropy of Long-period Comets Explained by Their Formation Process. Long-period comets coming from the Oort cloud are thought to be planetesimals formed in the planetary region on the ecliptic plane. We have investigated the orbital evolution of these bodies due to the Galactic tide. We extended our previous work and derived analytical solutions to the Galactic longitude and latitude of the direction of aphelion, L and B. Using the analytical solutions, we show that the ratio of the periods of evolution of L and B is very close to either 2 or $\infty $ for initial eccentricities ei ≃ 1, as is true for the Oort cloud comets. From the relation between L and B, we predict that Oort cloud comets returning to the planetary region are concentrated on the ecliptic plane and a second plane, which we call the "empty ecliptic." This consists in a rotation of the ecliptic around the Galactic pole by 180°. Our numerical integrations confirm that the radial component of the Galactic tide, which is neglected in the derivation of the analytical solutions, is not strong enough to break the relation between L and B derived analytically. Brief examination of observational data shows that there are concentrations near both the ecliptic and the empty ecliptic. We also show that the anomalies of the distribution of B of long-period comets mentioned by several authors are explained by the concentrations on the two planes more consistently than by previous explanations.

Keywords: Oort cloud, Long period comets, Comets
A VIPA Spectrograph with Ultra-high Resolution and Wavelength Calibration for Astronomical Applications. A prototype spectrograph using a Virtually Imaged Phased Array (VIPA) as the main dispersion element is presented, and its performance is fully examined in our laboratory. The single-mode, fiber-fed spectrograph with simultaneous wavelength calibration possesses a spectral resolution well in excess of $R\approx 1.12\times {10}^{6}$ while the size of the VIPA is several orders of magnitude smaller than that of a conventional échelle with comparable resolution. In laboratory tests, the VIPA-based instrument with a homemade Yb:fiber ring laser frequency comb demonstrates a mode-to-mode tracking stability of 41 cm s-1 over a period of 6 hr. The VIPA spectrograph has promising applications in various astronomical observations in which ultra-high resolution and calibration precision are imperative, such as solar physics research, exoplanet searching with the radial velocity method, and O2 detection in the atmosphere of Earth-like planets. Ultimately, feasible optimizations for night-sky observations under seeing limited conditions are discussed.

Keywords: High resolution spectroscopy, Astronomical techniques, Astronomical instrumentation, Astronomical methods