Sazuna/UAT_keywords huggingface dataset:
The Breakthrough Listen Search for Intelligent Life: Observations of 1327 Nearby Stars Over 1.10-3.45 GHz. Breakthrough Listen (BL) is a 10 year initiative to search for signatures of technologically capable life beyond Earth via radio and optical observations of the local universe. A core part of the BL program is a comprehensive survey of 1702 nearby stars at radio wavelengths (1-10 GHz). Here, we report on observations with the 64 m CSIRO Parkes radio telescope in New South Wales, Australia, and the 100 m Robert C. Byrd Green Bank radio telescope in West Virginia, USA. Over 2016 January to 2019 March, a sample of 1138 stars was observed at Green Bank using the 1.10-1.90 GHz and 1.80-2.80 GHz receivers, and 189 stars were observed with Parkes over 2.60-3.45 GHz. We searched these data for the presence of engineered signals with Doppler-acceleration drift rates between ±4 Hz s-1. Here, we detail our data analysis techniques and provide examples of detected events. After excluding events with characteristics consistent with terrestrial radio interference, we are left with zero candidates. That is, we find no evidence of putative radio transmitters above $2.1\times {10}^{12}$ W, and $9.1\times {10}^{12}$ W for Green Bank and Parkes observations, respectively. These observations constitute the most comprehensive search over 1.10-3.45 GHz for technosignatures to date. All data products, totaling ∼219 TB, are available for download as part of the first BL data release (DR1), as described in a companion paper.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Astrobiology
Benzyne in V4334 Sqr: A Quest for the Ring with SOFIA/EXES. Large aromatic molecules are ubiquitous in both circumstellar and interstellar environments. Detection of small aromatic molecules, such as benzene (C6H6) and benzyne (C6H4), are rare in astrophysical environments. Detection of such species will have major implications for our understanding of the astrochemistry involved in the formation of the molecules necessary for life, including modeling the chemical pathways to the formation of larger hydrocarbon molecules. We conducted a search for the infrared 18 μm spectral signature of benzyne in V4334 Sgr with the Stratospheric Observatory for Infrared Astronomy (SOFIA)/Echelon-Cross-Echelle Spectrograph (EXES) finding no evidence for a feature at the sensitivity of our observations.

Keywords: Asymptotic giant branch stars, Circumstellar dust, Astrochemistry
The Quadruple System HIP 45734. HIP 45734 is a quadruple system of 2 + 2 architecture located at 68 pc from the Sun. The outer 9″ system A,B has a period of ∼104 yr. The subsystem Aa,Ab is a visual binary with a period of 20.1 yr and an eccentricity of 0.78. Its periastron in 2019.1 was observed spectroscopically, yielding masses (1.10 ± 0.04 and 0.98 ± 0.03 ${{ \mathcal M }}_{\odot }$ ) and orbital parallax, 14.90 ± 0.37 mas. The masses, luminosities, and colors approximately agree with evolutionary models of main-sequence stars. Component Aa has a detectable lithium line, whereas in Ab it is absent. The pair Ba,Bb is a single-lined spectroscopic binary with a period of 0.55552 day and an orbital inclination of ∼45° derived by modeling the rotationally broadened line profile with flat bottom. The mass of Bb is ∼0.4 ${{ \mathcal M }}_{\odot }$ . Star B is chromospherically active (an X-ray source); its flux is modulated with the orbital period by starspots, in addition to occasional flares. The system is probably older than ∼600 Myr; it does not belong to any known moving group.

Keywords: Spectroscopic binary stars, Multiple stars, Binary stars, Visual binary stars
orbitize!: A Comprehensive Orbit-fitting Software Package for the High-contrast Imaging Community. orbitize! is an open-source, object-oriented software package for fitting the orbits of directly imaged objects. It packages the Orbits for the Impatient (OFTI) algorithm and a parallel-tempered Markov Chain Monte Carlo (MCMC) algorithm into a consistent and intuitive Python API. orbitize! makes it easy to run standard astrometric orbit fits; in less than 10 lines of code, users can read in data, perform one fit using OFTI and another using MCMC, and make two publication-ready figures. Extensive pedagogical tutorials, intended to be navigable by both orbit-fitting novices and seasoned experts, are available on our documentation page. We have designed the orbitize! API to be flexible and easy to use/modify for unique cases. orbitize! was designed by members of the exoplanet imaging community to be a central repository for algorithms, techniques, and know-how developed by this community. We intend for it to continue to expand and change as the field progresses and new techniques are developed, and call for community involvement in this process. Complete and up-to-date documentation is available at orbitize.info, and the source code is available at github.com/sblunt/orbitize.

Keywords: Open source software, Orbit determination
High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances. Abundances of lithium, carbon, and oxygen have been derived using spectral synthesis for a sample of 249 bright F, G, and K Northern Hemisphere dwarf stars from the high-resolution spectra acquired with the VUES spectrograph at the Molėtai Astronomical Observatory of Vilnius University. The sample stars have metallicities, effective temperatures, and ages between (-0.7 $\div$ 0.4) dex, (5000 $\div$ 6900) K, (1 $\div$ 12) Gyr, accordingly. We confirm a so far unexplained lithium abundance decrease at supersolar metallicities—A(Li) in our sample stars, which drop by 0.7 dex in the [Fe/H] range from +0.10 to +0.55 dex. Furthermore, we identified stars with similar ages, atmospheric parameters, and rotational velocities, but with significantly different lithium abundances, which suggests that additional specific evolutionary factors should be taken into account while interpreting the stellar lithium content. Nine stars with predominantly supersolar metallicities, i.e., about 12% among 78 stars with C and O abundances determined, have the C/O number ratios larger than 0.65, thus may form carbon-rich rocky planets. Ten planet-hosting stars, available in our sample, do not show a discernible difference from the stars with no planets detected regarding their lithium content.

Keywords: High resolution spectroscopy, Solar neighborhood, Chemical abundances, Dwarf stars
OGLE-2016-BLG-1227L: A Wide-separation Planet from a Very Short-timescale Microlensing Event. We present the analysis of the microlensing event OGLE-2016-BLG-1227. The light curve of this short-duration event appears to be a single-lens event affected by severe finite-source effects. Analysis of the light curve based on a single-lens single-source (1L1S) model yields very small values of the event timescale, ${t}_{{\rm{E}}}\sim 3.5$ days, and the angular Einstein radius, ${\theta }_{{\rm{E}}}\sim 0.009$ mas, making the lens a candidate of a free-floating planet. Close inspection reveals that the 1L1S solution leaves small residuals with an amplitude of ΔI ≲ 0.03 mag. We find that the residuals are explained by the existence of an additional widely separated heavier lens component, indicating that the lens is a wide-separation planetary system rather than a free-floating planet. From Bayesian analysis, it is estimated that the planet has a mass of ${M}_{{\rm{p}}}={0.79}_{-0.39}^{+1.30}\,{M}_{{\rm{J}}}$ and it is orbiting a low-mass host star with a mass of ${M}_{\mathrm{host}}={0.10}_{-0.05}^{+0.17}\,{M}_{\odot }$ located with a projected separation of ${a}_{\perp }={3.4}_{-1.0}^{+2.1}$ au. The planetary system is located in the Galactic bulge with a line-of-sight separation from the source star of ${D}_{\mathrm{LS}}={1.21}_{-0.63}^{+0.96}$ kpc. The event shows that there is a range of deviations in the signatures of host stars for apparently isolated planetary lensing events and that it is possible to identify a host even when a deviation is subtle.

Keywords: Gravitational microlensing exoplanet detection, Gravitational lensing
Yarkovsky Drift Detections for 247 Near-Earth Asteroids. The Yarkovsky effect is a thermal process acting upon the orbits of small celestial bodies, which can cause these orbits to slowly expand or contract with time. The effect is subtle ( $\left\langle {da}/{dt}\right\rangle \sim {10}^{-4}$ au My-1 for a 1 km diameter object) and is thus generally difficult to measure. We analyzed both optical and radar astrometry for 600 Near-Earth Asteroids (NEAs) for the purpose of detecting and quantifying the Yarkovsky effect. We present 247 NEAs with measured drift rates, which is the largest published set of Yarkovsky detections. This large sample size provides an opportunity to examine the Yarkovsky effect in a statistical manner. In particular, we describe two independent population-based tests that verify the measurement of Yarkovsky orbital drift. First, we provide observational confirmation for the Yarkovsky effect's theoretical size dependence of 1/D, where D is diameter. Second, we find that the observed ratio of negative to positive drift rates in our sample is 2.34, which, accounting for bias and sampling uncertainty, implies an actual ratio of ${2.7}_{-0.7}^{+0.3}$ . This ratio has a vanishingly small probability of occurring due to chance or statistical noise. The observed ratio of retrograde to prograde rotators is two times lower than the ratio expected from numerical predictions from NEA population studies and traditional assumptions about the sense of rotation of NEAs originating from various main belt escape routes. We also examine the efficiency with which solar energy is converted into orbital energy and find a median efficiency in our sample of 12%. We interpret this efficiency in terms of NEA spin and thermal properties.

Keywords: Astrometry, The Sun, Asteroids, Orbit determination
Constraining Orbital Periods from Nonconsecutive Observations: Period Estimates for Long-period Planets in Six Systems Observed by K2 During Multiple Campaigns. Most planetary discoveries with the K2 and Transiting Exoplanet Survey Satellite (TESS) missions are restricted to short periods because of the limited duration of observation. However, the re-observation of sky area allows for the detection of longer period planets. We describe new transits detected in six candidate planetary systems that were observed by multiple K2 mission campaigns. One of these systems is a multiplanet system with four candidate planets; we present new period constraints for two planets in this system. In the other five systems, only one transit is observed in each campaign, and we derive period constraints from this new data. The period distributions are highly multimodal resulting from missed potential transits in the gap between observations. Each peak in the distribution corresponds to transits at an integer harmonic of the two observed transits. We further detail a generalized procedure to constrain the period for planets with multiple observations with intervening gaps. Because long-period photometrically discovered planets are rare, these systems are interesting targets for follow-up observations and confirmation. Specifically, all six systems are bright enough (V = 10.4-12.7) to be amenable to radial velocity follow-up. This work serves as a template for period constraints in a host of similar yet-to-be-discovered planets in long baseline, temporally gapped observations conducted by the TESS mission.

Keywords: Exoplanet dynamics, Period determination, Transits, Exoplanets, Exoplanet astronomy, Exoplanet detection methods, Transit photometry
Kepler-1661 b: A Neptune-sized Kepler Transiting Circumbinary Planet around a Grazing Eclipsing Binary. We report the discovery of a Neptune-sized ( ${R}_{p}=3.87\pm 0.06{R}_{\oplus }$ ) transiting circumbinary planet, Kepler-1661 b, found in the Kepler photometry. The planet has a period of ∼175 days and its orbit precesses with a period of only 35 yr. The precession causes the alignment of the orbital planes to vary, and the planet is in a transiting configuration only ∼7% of the time as seen from Earth. As with several other Kepler circumbinary planets, Kepler-1661 b orbits close to the stability radius, and is near the (hot) edge of the habitable zone. The planet orbits a single-lined, grazing eclipsing binary, containing a 0.84 ${M}_{\odot }$ and 0.26 ${M}_{\odot }$ pair of stars in a mildly eccentric (e = 0.11), 28.2 day orbit. The system is fairly young, with an estimated age of ∼1-3 Gyr, and exhibits significant starspot modulations. The grazing eclipse configuration means the system is very sensitive to changes in the binary inclination, which manifests itself as a change in the eclipse depth. The starspots contaminate the eclipse photometry, but not in the usual way of inducing spurious eclipse timing variations. Rather, the starspots alter the normalization of the light curve, and hence the eclipse depths. This can lead to spurious eclipse depth variations, which are then incorrectly ascribed to binary orbital precession.

Keywords: Exoplanet astronomy, Timing variation methods, Eclipsing binary stars, Exoplanet detection methods, Transit photometry
Open Cluster IC 1369 and Its Vicinity: Multicolor Photometry and Gaia DR2 Astrometry. The open cluster IC 1369, located in Cygnus close to the galactic equator at the 89°6 longitude, and its vicinity are investigated by applying two-dimensional photometric classification of stars down to V = 19 mag measured in the Vilnius seven-color photometric system. Employing the Gaia DR2 coordinates, parallaxes, and proper motions, 143 cluster members are found having cluster membership probabilities ≥0.75. The hottest stars of the evolved main sequence are of spectral class B9. Distances to the cluster, determined by two methods based on the Gaia parallaxes, are 3280 and 3370 pc with an uncertainty of 400-500 pc. Employing the physical HR diagram with the coordinates $\mathrm{log}L/{L}_{\odot }$ versus $\mathrm{log}{T}_{\mathrm{eff}}$ and the Padova isochrones, the cluster age is found to be between 300 and 350 Myr. Among the cluster members we identified six red giants of spectral classes G5-G8 and luminosities II-III, 17 Am stars, one Ap star, and one B5 blue straggler. The extinction shows a steep rise up to ∼2.0 mag at 300-700 pc, caused by the extensions of the dust cloud LDN 970 and the Great Cygnus Rift, and up to ∼2.5 mag at the edge of the Perseus arm at 3.0 kpc. The extinction is almost constant between 0.9 and 2.5 kpc from the Sun. The average extinction of the cluster members is 2.54 mag. A systematic error of color excesses found in the Argonaut calculator results is discussed.

Keywords: Open star clusters, Hertzsprung Russell diagram, Stellar classification, Interstellar dust extinction
Variability in the Massive Open Cluster NGC 1817 from K2: A Rich Population of Asteroseismic Red Clump, Eclipsing Binary, and Main-sequence Pulsating Stars. We present a survey of variable stars detected in K2 Campaign 13 within the massive intermediate-age (∼1 Gyr) open cluster NGC 1817. We identify a complete sample of 44 red clump stars in the cluster, and have measured asteroseismic quantities (νmax and/or Δν) for 29 of them. Five stars showed suppressed dipole modes, and the occurrence rates indicate that mode suppression is unaffected by evolution through core helium burning. A subset of the giants in NGC 1817 (and in the similarly aged cluster NGC 6811) have νmax and Δν values at or near the maximum observed for core helium-burning stars, indicating they have core masses near the minimum for fully nondegenerate helium ignition. Further asteroseismic study of these stars can constrain the minimum helium core mass in red clump stars and the physics that determines this limit. Two giant stars show photometric variations on timescales similar to previously measured spectroscopic orbits. Thirteen systems in the field show eclipses, but only five are probable cluster members. We identify 32 δ Sct pulsators, 27 γ Dor candidates, and 7 hybrids that are probable cluster members, with most being new detections. We used the ensemble properties of the δ Sct stars to identify stars with possible radial pulsation modes. Among the oddities we have uncovered are: an eccentric orbit for a short-period binary containing a δ Sct pulsating star; a rare subgiant within the Hertzsprung gap showing δ Sct pulsations; and two hot γ Dor pulsating star candidates.

Keywords: Stellar distance, Spectroscopic binary stars, Low mass stars, Eclipsing binary stars, Open star clusters, Asteroseismology, Stellar evolution
A Rotation Rate for the Planetary-mass Companion DH Tau b. DH Tau b is a young planetary-mass companion orbiting at a projected separation of 320 au from its ∼2 Myr old host star DH Tau. With an estimated mass of 8-22 ${M}_{\mathrm{Jup}}$ this object straddles the deuterium-burning limit, and might have formed via core or pebble accretion, disk instability, or molecular cloud fragmentation. To shed light on the formation history of DH Tau b, we obtain the first measurement of rotational line broadening for this object using high-resolution (R ∼ 25,000) near-infrared spectroscopy from Keck/NIRSPEC. We measure a projected rotational velocity (v sin i) of 9.6 ± 0.7 km s-1, corresponding to a rotation rate that is between 9% and 15% of DH Tau b's predicted breakup speed. This low rotation rate is in good agreement with scenarios in which magnetic coupling between the companion and its circumplanetary disk during the late stages of accretion reduces angular momentum and regulates spin. We compare the rotation rate of DH Tau b to published values for other planetary-mass objects with masses between 0.3 and 20 ${M}_{\mathrm{Jup}}$ and find no evidence of a correlation between mass and rotation rate in this mass regime. Finally, we search for evidence of individual molecules in DH Tau b's spectrum and find that it is dominated by CO and H2O, with no evidence of the presence of CH4. This agrees with expectations given DH Tau b's relatively high effective temperature (∼2300 K).

Keywords: High resolution spectroscopy, Exoplanet formation, Brown dwarfs, Exoplanet atmospheres
KMT-2016-BLG-1836Lb: A Super-Jovian Planet from a High-cadence Microlensing Field. We report the discovery of a super-Jovian planet in the microlensing event KMT-2016-BLG-1836, which was found by the Korea Microlensing Telescope Network (KMTNet) high-cadence observations ( ${\rm{\Gamma }}\sim 4\,{\mathrm{hr}}^{-1}$ ). The planet-host mass ratio q ∼ 0.004. A Bayesian analysis indicates that the planetary system is composed of a super-Jovian ${M}_{\mathrm{planet}}={2.2}_{-1.1}^{+1.9}{M}_{{\rm{J}}}$ planet orbiting an M or K dwarf, ${M}_{\mathrm{host}}={0.49}_{-0.25}^{+0.38}{M}_{\odot }$ , at a distance of ${D}_{{\rm{L}}}={7.1}_{-2.4}^{+0.8}$ kpc. The projected planet-host separation is ${3.5}_{-0.9}^{+1.1}$ au, implying that the planet is located beyond the snow line of the host star. Future high-resolution images can potentially strongly constrain the lens brightness and thus the mass and distance of the planetary system. Without considering detailed detection efficiency, selection, or publication biases, we find a potential mass-ratio desert at -3.7 ≲ log q ≲ -3.0 for the 31 published KMTNet planets.

Keywords: Gravitational microlensing exoplanet detection
Optical Linear Polarization toward the Open Star Cluster Casado Alessi 1. We present B-, V-, R-, and I-band linear polarimetric observations of 73 stars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi 1). We aim to use polarimetry as a tool to investigate the properties and distribution of dust grains toward the direction of the cluster. The polarimetric observations were carried out using the ARIES IMaging POLarimeter mounted at the 104 cm telescope of ARIES, Nainital (India). Using the Gaia photometric data the age and distance of the cluster are estimated to be 0.8 ± 0.1 Gyr and 673 ± 98 pc, respectively. A total of 66 stars with a 26' radius from the cluster are identified as members of the cluster using the astrometric approach. Out of these 66 members, 15 stars were observed polarimetrically and found to have the same value of polarization. The majority of the stars in the region follow the general law of polarization for the interstellar medium, indicating that polarization toward the cluster Alessi 1 is dominated by foreground dust grains. The average values of the maximum polarization (Pmax) and the wavelength corresponding to the maximum polarization (λmax) toward the cluster are found to be 0.83 ± 0.03% and 0.59 ± 0.04 μm, respectively. Also, dust grains toward the cluster appear to be aligned, possibly due to the galactic magnetic field.

Keywords: Interstellar dust, Interstellar dust extinction, Starlight polarization, Interstellar medium, Open star clusters, Polarimetry
A Sub-Neptune-sized Planet Transiting the M2.5 Dwarf G 9-40: Validation with the Habitable-zone Planet Finder. We validate the discovery of a 2-Earth-radii sub-Neptune-sized planet around the nearby high-proper-motion M2.5 dwarf G 9-40 (EPIC 212048748), using high-precision, near-infrared (NIR) radial velocity (RV) observations with the Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based photometry with a custom narrowband photometric filter, and adaptive optics imaging. At a distance of d = 27.9 $\,\mathrm{pc}$ , G 9-40b is the second-closest transiting planet discovered by K2 to date. The planet's large transit depth (∼3500 ppm), combined with the proximity and brightness of the host star at NIR wavelengths (J = 10, K = 9.2), makes G 9-40b one of the most favorable sub-Neptune-sized planets orbiting an M dwarf for transmission spectroscopy with James Webb Space Telescope, ARIEL, and the upcoming Extremely Large Telescopes. The star is relatively inactive with a rotation period of ∼29 days determined from the K2 photometry. To estimate spectroscopic stellar parameters, we describe our implementation of an empirical spectral-matching algorithm using the high-resolution NIR HPF spectra. Using this algorithm, we obtain an effective temperature of ${T}_{\mathrm{eff}}=3404\pm 73\,{\rm{K}}$ and metallicity of $[\mathrm{Fe}/{\rm{H}}]=-0.08\pm 0.13$ . Our RVs, when coupled with the orbital parameters derived from the transit photometry, exclude planet masses above 11.7M⊕ with 99.7% confidence assuming a circular orbit. From its radius, we predict a mass of $M={5.0}_{-1.9}^{+3.8}{M}_{\oplus }$ and an RV semiamplitude of $K={4.1}_{-1.6}^{+3.1}\,{\rm{m}}\ {{\rm{s}}}^{-1}$ , making its mass measurable with current RV facilities. We urge further RV follow-up observations to precisely measure its mass, to enable precise transmission spectroscopic measurements in the future.

Keywords: Exoplanet detection methods, Exoplanets, Exoplanet systems, Mini Neptunes, Exoplanet astronomy, Low mass stars, Radial velocity, Transit photometry