Sazuna/UAT_keywords huggingface dataset:
True Masses of the Long-period Companions to HD 92987 and HD 221420 from Hipparcos-Gaia Astrometry. The extensive time span of modern radial velocity surveys has made the discovery of long-period substellar companions more common in recent years; however, measuring the true masses of these objects remains challenging. Astrometry from the Gaia mission is expected to provide mass measurements for many of these long-period companions, but these data are not yet available. However, combining proper-motion data from Gaia DR2 and the earlier Hipparcos mission makes it possible to measure true masses of substellar companions in favorable cases. In this work, we combine radial velocities with Hipparcos-Gaia astrometry to measure the true masses of two recently discovered long-period substellar companion candidates, HD 92987 B and HD 221420 b. In both cases, we find that the true masses are significantly higher than implied by radial velocities alone. A 2087 ± 19 m s-1 astrometric signal reveals that HD 92987 B is not close to its 17 MJ minimum mass but is instead a 0.2562 ± 0.0045 M☉ star viewed at a near-polar orbital inclination, whereas the 22.9 ± 2.2 MJ HD 221420 b can be plausibly interpreted as a high-mass "superplanet" or a low-mass brown dwarf. With semimajor axes of ∼10 au, both companions are interesting targets for direct imaging, and HD 221420 b in particular would be a benchmark metal-rich substellar object if it proves possible to directly detect. Our results demonstrate the power of Hipparcos-Gaia astrometry for studying long-period planet and brown dwarf candidates discovered from radial velocity surveys.

Keywords: Brown dwarfs, Binary stars, Exoplanets, Low mass stars, Astrometry
Photometric Study and Absolute Parameter Estimation of Six Totally Eclipsing Contact Binaries. High precision CCD observations of six totally eclipsing contact binaries were presented and analyzed. It is found that only one target is an A-type contact binary (V429 Cam), while the others are W-type contact ones. By analyzing the times of light minima, we discovered that two of them exhibit secular period increase while three manifest long-term period decrease. For V1033 Her, a cyclic variation superimposed on the long-term increase was discovered. By comparing the Gaia distances with those calculated by the absolute parameters of 173 contact binaries, we found that the Gaia distance can be applied to estimate the absolute parameters for most contact binaries. The absolute parameters of our six targets were estimated using their Gaia distances. The evolutionary status of contact binaries was studied, and we found that the A- and W-subtype contact binaries may have different formation channels. The relationship between the spectroscopic and photometric mass ratios for 101 contact binaries was presented. It was discovered that the photometric mass ratios are in good agreement with the spectroscopic ones for almost all of the totally eclipsing systems, which is corresponding to the results derived by Pribulla et al. and Terrell &amp; Wilson.

Keywords: Close binary stars, Eclipsing binary stars, Fundamental parameters of stars, Stellar evolution
Precision Millimeter Astrometry of the α Centauri AB System. Alpha Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its habitable zone. Here, we describe initial results from an Atacama Large Millimeter/submillimeter Array (ALMA) program to search for planets in the α Cen AB system using differential astrometry at millimeter wavelengths. Our initial results include new absolute astrometric measurements of the proper motion, orbital motion and parallax of the α Cen system. These lead to an improved knowledge of the physical properties of both α Cen A and B. Our estimates of ALMA's relative astrometric precision suggest that we will ultimately be sensitive to planets of a few tens of Earth mass in orbits from 1 to 3 au, where stable orbits are thought to exist.

Keywords: Fundamental parameters of stars, Astrometric binary stars, Radio astrometry, Main sequence stars
KMT-2019-BLG-2073: Fourth Free-floating Planet Candidate with θ<SUB>E</SUB> &lt; 10 μas. We analyze the very short Einstein timescale (tE ≃ 7 hr) event KMT-2019-BLG-2073. Making use of the pronounced finite-source effects generated by the clump giant source, we measure the Einstein radius θE ≃ 4.8 μas and so infer a mass $M=59\,{M}_{\oplus }{({\pi }_{\mathrm{rel}}/16\mu \mathrm{as})}^{-1}$ , where πrel is the lens-source relative parallax. We find no significant evidence for a host of this planetary-mass object, though one could be present at sufficiently wide separation. If so, it would be detectable after about 10 yr. This is the fourth isolated microlens with a measured Einstein radius θE &lt; 10 μas, which we argue is a useful threshold for a "likely free-floating planet (FFP)" candidate. We outline a new approach to constructing a homogeneous sample of giant-star finite-source/point-lens (FSPL) events, within which the subsample of FFP candidates can be statistically analyzed. We illustrate this approach using 2019 KMTNet data and show that there appears to be a large θE gap between the two FFP candidates and the 11 other FSPL events. We argue that such sharp features are more identifiable in a sample selected on θE compared to the traditional approach of identifying candidates based on short tE.

Keywords: Gravitational microlensing exoplanet detection
A Tidal Origin for a Three-body Resonance in Kepler-221. Over the course of the last two decades, traditional models of planet formation have been repeatedly challenged by the emerging census of extrasolar planets. Key among them is the orbital architecture problem: while standard models of orbital migration predict resonant orbits for short-period objects, most planets do not appear to lie in orbital resonances. Here, we show that the four-planet system Kepler-221, not previously recognized to have active orbital resonances, has a three-body commensurability relation unique within the Kepler sample. Using a suite of numerical experiments as well as a perturbative analysis, we demonstrate that this system likely began as a resonant chain and proceeded to undergo large-scale divergence away from resonance, under the action of tidal dissipation. Our results further indicate that obliquity tides, driven by a secular spin-orbit resonance and mutual inclination, are an excellent candidate for driving this orbital divergence, and that the high tidal luminosity may also explain the anomalous size of planet b, which lies within the Fulton radius gap.

Keywords: Exoplanet dynamics, Exoplanet evolution, Exoplanet tides, Orbital resonances
KMT-2019-BLG-0371 and the Limits of Bayesian Analysis. We show that the perturbation at the peak of the light curve of microlensing event KMT-2019-BLG-0371 is explained by a model with a mass ratio between the host star and planet of q ∼ 0.08. Due to the short event duration (tE ∼ 6.5 days), the secondary object in this system could potentially be a massive giant planet. A Bayesian analysis shows that the system most likely consists of a host star with a mass ${M}_{{\rm{h}}}={0.09}_{-0.05}^{+0.14}{M}_{\odot }$ and a massive giant planet with a mass ${M}_{{\rm{p}}}={7.70}_{-3.90}^{+11.34}{M}_{\mathrm{Jup}}$ . However, the interpretation of the secondary as a planet (i.e., as having Mp &lt; 13MJup) rests entirely on the Bayesian analysis. Motivated by this event, we conduct an investigation to determine which constraints meaningfully affect Bayesian analyses for microlensing events. We find that the masses inferred from such a Bayesian analysis are determined almost entirely by the measured value of θE and are relatively insensitive to other factors such as the direction of the event (ℓ, b), the lens-source relative proper motion μrel, or the specific Galactic model prior.

Keywords: Binary lens microlensing
Multiband Transit Follow-up Observations of Five Hot Jupiters with Critical Noise Treatments: Improved Physical Properties. The most challenging limitation in transit photometry arises from the noises in the photometric signal. In particular, the ground-based telescopes are heavily affected by the noise due to perturbation in the Earth's atmosphere. Use of telescopes with large apertures can improve the photometric signal-to-noise ratio to a great extent. However, detecting a transit signal out of a noisy light curve of the host star and precisely estimating the transit parameters call for various noise reduction techniques. Here, we present multiband transit photometric follow-up observations of five hot Jupiters e.g., HAT-P-30 b, HAT-P-54 b, WASP-43 b, TrES-3 b, and XO-2 N b, using the 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle, and the 1.3 m J. C. Bhattacharya Telescope at the Vainu Bappu Observatory, Kavalur. Our critical noise treatment approach includes techniques such as wavelet denoising and Gaussian process regression, which effectively reduce both time-correlated and time-uncorrelated noise components from our transit light curves. In addition to these techniques, use of our state-of-the-art model algorithms have allowed us to estimate the physical properties of the target exoplanets with a better accuracy and precision compared to the previous studies.

Keywords: Hot Jupiters, Exoplanets, Gaussian Processes regression, Wavelet analysis, Markov chain Monte Carlo, Transit photometry
The Rarity of Very Red Trans-Neptunian Objects in the Scattered Disk. We investigate the origins of the photometrically very red (VR) and less red (LR) trans-Neptunian objects (TNOs). We first reanalyze the data set of Marsset et al. and find that in addition to the known color-inclination correlation in hot TNOs, a similar trend exists for color-eccentricity. We show that VR TNOs are sharply constrained to eccentricities &lt;0.42 and inclinations &lt;21°, leading to a paucity of VR scattered disk and distant mean motion resonance objects. We then interpret these findings using N-body simulations accounting for Neptune's outward migration into a massless particles disk and find that these observations are best reproduced with an LR-to-VR color transition line between ∼38 and 42 au in the primordial disk, separating the objects' formation locations. For an initial surface density profile (Σ ∝ 1/r2), a color transition around 38 au is needed to explain the high abundance of VR plutinos, but it creates too many VR scattered disk objects, while a transition line around 42 au seems to better reproduce the scattered disk colors but creates virtually no VR plutinos. Our simulations furthermore show that the rarity of VR particles at high eccentricity is possibly due to the absence of sweeping higher-order MMRs, and secular resonances, beyond 42 au. Inspecting individual populations, we show that the majority of VR SDOs originate as objects trapped in Neptune's second- and third-order MMRs. These then evolve due to diffusion, scattering, Kozai-Lidov cycles, and secular resonances into their current orbits. Future unbiased color surveys are crucial to better constrain the TNOs dynamical origins.

Keywords: Kuiper belt, Small Solar System bodies, Trans-Neptunian objects
Meteoroid Stream of Comet C/1961 T1 (Seki) and Its Relation to the December -Virginids and -Sagittariids. We answer the question of whether long-period comet C/1961 T1 (Seki) is the parent body of a meteor shower observed in Earths atmosphere. We model discrete parts of a meteoroid stream associated with this comet and follow the orbital evolution of its particles via a numerical integration of their orbits. The gravitational perturbations of major planets and the PoyntingRobertson effect, which influences the motion of the particles, are taken into account. We predict two showers which are related to C/1961 T1. One of these showers was identified with the December -Virginids, #502. This identification confirms an earlier suggested relationship between the shower and the comet. The second predicted shower was identified with the -Sagittariids, #657. The radiant areas of both showers are symmetrical in respect to the apex of Earths heliocentric motion.

Keywords: Meteor showers, Comets, Meteor streams
Optical Variability of ICRF3 Quasars in the Pan-STARRS 3Pi Survey with Functional Principal Component Analysis. We make use of individual (epoch) detection data from the Pan-STARRS 3 survey for 2863 optical ICRF3 counterparts in the five wavelength bands g, r, i, z, and y, published as part of the Data Release 2. A dedicated method based on the Functional Principal Component Analysis is developed for these sparse and irregularly sampled data. With certain regularization and normalization constraints, it allows us to obtain uniform and compatible estimates of the variability amplitudes and average magnitudes between the passbands and objects. We find that the starting assumption of affinity of the light curves for a given object at different wavelengths is violated for several percent of the sample. The distributions of rms variability amplitudes are strongly skewed toward small values, peaking at 0.1 mag with tails stretching to 2 mag. Statistically, the lowest variability is found for the r band and the largest for the reddest y band. A small brighter-redder effect is present, with amplitudes in y greater than amplitudes in g in 57 of the sample. The variability versus redshift dependence shows a strong decline with z toward redshift 3, which we interpret as the time dilation of the dominant time frequencies. The colors of radio-loud ICRF3 quasars are correlated with redshift in a complicated, wavy pattern governed by the emergence of brightest emission lines within the five passbands.

Keywords: Quasars, Space astrometry, Radio source catalogs
A Canonical Transformation to Eliminate Resonant Perturbations. I.. We study dynamical systems that admit action-angle variables at leading order, which are subject to nearly resonant perturbations. If the frequencies characterizing the unperturbed system are not in resonance, the long-term dynamical evolution may be integrated by orbit-averaging over the high-frequency angles, thereby evolving the orbit-averaged effect of the perturbations. It is well known that such integrators may be constructed via a canonical transformation, which eliminates the high-frequency variables from the orbit-averaged quantities. An example of this algorithm in celestial mechanics is the von Zeipel transformation. However, if the perturbations are inside or close to a resonance, i.e., the frequencies of the unperturbed system are commensurate; these canonical transformations are subject to divergences. We introduce a canonical transformation that eliminates the high-frequency phase variables in the Hamiltonian without encountering divergences. This leads to a well-behaved symplectic integrator. We demonstrate the algorithm through two examples: a resonantly perturbed harmonic oscillator and the gravitational three-body problem in mean motion resonance.

Keywords: Celestial mechanics
Feasibility of Detecting Interstellar Panspermia in Astrophysical Environments. The proposition that life can spread from one planetary system to another (interstellar panspermia) has a long history, but this hypothesis is difficult to test through observations. We develop a mathematical model that takes parameters such as the microbial survival lifetime, the stellar velocity dispersion, and the dispersion of ejecta into account in order to assess the prospects for detecting interstellar panspermia. We show that the correlations between pairs of life-bearing planetary systems (embodied in the pair-distribution function from statistics) may serve as an effective diagnostic of interstellar panspermia, provided that the velocity dispersion of ejecta is greater than the stellar dispersion. We provide heuristic estimates of the model parameters for various astrophysical environments and conclude that open clusters and globular clusters appear to represent the best targets for assessing the viability of interstellar panspermia.

Keywords: Habitable planets, Astrobiology, Milky Way Galaxy
High-resolution Near-infrared Spectroscopy of Diffuse Sources around MWC 1080. To reveal the origins of diffuse H emissions observed around the Herbig star MWC 1080, we have performed a high-resolution near-infrared (NIR) spectroscopic observation using the Immersion Grating Infrared Spectrograph. In the NIR H and K bands, we detected various emission lines (six hydrogen Brackett lines, seven H2 lines, and an [Fe II] line) and compared their spatial locations with the optical (H and [S II]) and radio (13CO and CS) line maps. The shock-induced H2 and [Fe II] lines indicate the presence of multiple outflows, consisting of at least three associated young stars in this region. The kinematics of H2 and [Fe II] near the northeast (NE) cavity edge supports the idea that the NE main outflow from MWC 1080A is the blueshifted one with a low inclination angle. The H2 and [Fe II] lines near the southeast molecular region newly reveal that additional highly blueshifted outflows originate from other young stars. The fluorescent H2 lines were found to trace photodissociation regions formed on the cylindrical surfaces of the main outflow cavity, which are expanding outward with a velocity of about 1015 km s1. For the H emission, we identify its components associated with two stellar outflows and two young stars in addition to the dominant component of MWC 1080A scattered by dust. We also report a few faint H features located 0.4 pc away in the southwest direction from MWC 1080A, which lie near the axes of the NE main outflow and one of the newly identified outflows.

Keywords: High resolution spectroscopy, Herbig Ae/Be stars, Herbig-Haro objects, Stellar jets, Star forming regions, H I line emission, Young stellar objects, Stellar winds, Interstellar medium, Near infrared astronomy
Natural Night Sky Brightness during Solar Minimum. In 2018, Solar Cycle 24 entered into a solar minimum phase. During this period, 11 million zenithal night sky brightness (NSB) data were collected at different dark sites around the planet, including astronomical observatories and natural protected areas, with identical broadband Telescope Encoder and Sky Sensor photometers (based on the Unihedron Sky Quality Meter TLS237 sensor). A detailed observational review of the multiple effects that contribute to the NSB measurement has been conducted with optimal filters designed to avoid brightening effects by the Sun, the Moon, clouds, and other astronomical sources (the Galaxy and zodiacal light). The natural NSB has been calculated from the percentiles for 44 different photometers by applying these new filters. The pristine night sky was measured to change with an amplitude of 0.1 mag/arcsec2 in all the photometers, which is suggested to be due to NSB variations on scales of up to months and to be compatible with semiannual oscillations. We report the systematic observation of short-time variations in NSB on the vast majority of the nights and find these to be related to airglow events forming above the mesosphere.

Keywords: Observational astronomy, Night sky brightness, Astronomy data analysis, Astronomical site protection, Astronomical instrumentation, Atmospheric effects, Photometer
Primary Velocity and Orbital Phase Effects on Planetary Detectability from Small Epoch Number Data Sets. Cross-correlation analyses of high-resolution spectroscopic data have recently shown great success in directly detecting planetary signals and enabling the characterization of their atmospheres. One such technique aims to observe a system at multiple epochs and combine the measured planetary radial velocities from each epoch into a measurement of the planetary Keplerian orbital velocity Kp, constituting a direct detection of the planetary signal. Recent work has shown that in few-epoch (5) data sets, unintended structure can arise at a high level, obscuring the planetary detection. In this work, we look to simulations to examine whether there are ways to reduce this structured noise in few-epoch data sets by careful planning of observations. The choice of observation date allows observers to select the primary (stellar) velocity through a set systemic velocity and chosen barycentric velocity and the planetary orbital phase so we focus on the effects of these two parameters. We find that epochs taken when the primary velocity is near zero and the stellar lines remain relatively fixed to the telluric rest-frame greatly reduce the level of structured noise and allow for much stronger planetary detections, on average more than twice the significance of detections made with epochs using randomly selected primary velocities. Following these results, we recommend that observers looking to build up high-resolution multi-epoch data sets target nights when their system has a near-zero primary velocity.

Keywords: High resolution spectroscopy, Radial velocity, Exoplanet atmospheres
Stability of Neptunes Distant Resonances in the Presence of Planet Nine. Trans-Neptunian Objects (TNOs) in the scattered disk with 50 a 100 au are thought to cluster near Neptunes n:1 resonances (e.g., 3:1, 4:1, and so on). While these objects spend lengthy periods of time at large heliocentric distances, if their perihelia remain less than around 40 au, their dynamical evolution is still largely coupled to Neptunes. Conversely, around a dozen extreme TNOs with a 250 au and detached perihelia seem to exist in a regime where they are too distant to be affected by the giant planets and too close for their dynamics to be governed by external forces. Recent work suggests that the apparent alignment of these orbits in physical space is a signature of gravitational shepherding by a distant massive planet. In this paper, we investigate the evolution of TNOs in each of Neptunes n:1 resonances between the 3:1 and 14:1. We conclude that both resonant and nonresonant objects beyond the 12:1 near 157 au are removed rather efficiently via perturbations from the hypothetical Planet Nine. Additionally, we uncover a population of simulated TNOs with a 100 au, 40 q 45 au, and low inclinations that experience episodes of resonant interactions with both Neptune and Planet Nine. Finally, we simulate the evolution of observed objects with a &gt; 100 au and identify several TNOs that are potentially locked in n:1 resonances with Neptune, including the most distant known resonant candidates, 2014 JW80 and 2014 OS394,which appear to be in the 10:1 and 11:1 resonances, respectively. Our results suggest that the detection of similar remote objects might provide a useful constraint on hypotheses invoking the existence of additional distant planets.

Keywords: Small Solar System bodies, Kuiper belt, Resonant Kuiper belt objects, Detached objects, Trans-Neptunian objects