Sazuna/UAT_keywords huggingface dataset:
The K2 and TESS Synergy. II. Revisiting 26 Systems in the TESS Primary Mission. The legacy of NASA's K2 mission has provided hundreds of transiting exoplanets that can be revisited by new and future facilities for further characterization, with a particular focus on studying the atmospheres of these systems. However, the majority of K2-discovered exoplanets have typical uncertainties on future times of transit within the next decade of greater than 4 hr, making observations less practical for many upcoming facilities. Fortunately, NASA's Transiting Exoplanet Survey Satellite (TESS) mission is reobserving most of the sky, providing the opportunity to update the ephemerides for ~300 K2 systems. In the second paper of this series, we reanalyze 26 single-planet, K2-discovered systems that were observed in the TESS primary mission by globally fitting their K2 and TESS light curves (including extended mission data where available), along with any archival radial velocity measurements. As a result of the faintness of the K2 sample, 13 systems studied here do not have transits detectable by TESS. In those cases, we refit the K2 light curve and provide updated system parameters. For the 23 systems with M * ≳ 0.6 M ⊙, we determine the host star parameters using a combination of Gaia parallaxes, spectral energy distribution fits, and MESA Isochrones and Stellar Tracks stellar evolution models. Given the expectation of future TESS extended missions, efforts like the K2 and TESS Synergy project will ensure the accessibility of transiting planets for future characterization while leading to a self-consistent catalog of stellar and planetary parameters for future population efforts.

Keywords: Ephemerides, Exoplanet catalogs, Exoplanets, Exoplanet systems, Exoplanet astronomy
Drift Performance and Chromatic Thermal Response of a Temperature Stabilized Solid-etalon Calibrator. Etalon-based calibrators have rapidly gained popularity over the past decade in the field of high-precision radial velocity and high-resolution spectroscopy studies. Solid etalons are compact, pressure insensitive, commercially available alternatives to customized air spaced Fabry-Perot etalons. For tight-budget projects and weight-constricted missions, calibration system built from solid etalon is an interesting option to explore. For those, achievable spectral stability becomes the biggest question due to increased thermal sensitivity of the cavity material. Here, the design and performance of a low-cost solid-etalon calibrator is presented. A dual-loop temperature control system keeps the temperature fluctuations to within 1 mK rms when fully stabilized. Drift performance was tracked simultaneously with a laser frequency comb and the chromatic thermal response is measured through temperature tuning. The results indicate that a thermally controlled solid-etalon system can demonstrate sufficient short-term stability (&lt;1 m s-1) for precise wavelength calibration in combination with a hollow-cathode lamp, and the measured drift and chromatic thermal response agree with theoretical predictions. Such systems are plausible candidates for cost-effective calibration of m s-1 level precision radial velocity instruments with improvement in thermal isolation, optimization in data processing, and long-term testing in the foreseeable future.

Keywords: Fabry-Perot interferometers, Calibration, High resolution spectroscopy, Radial velocity
The PEPSI Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy. Recent observations have shown that the atmospheres of ultrahot Jupiters (UHJs) commonly possess temperature inversions, where the temperature increases with increasing altitude. Nonetheless, which opacity sources are responsible for the presence of these inversions remains largely observationally unconstrained. We used LBT/PEPSI to observe the atmosphere of the UHJ KELT-20 b in both transmission and emission in order to search for molecular agents which could be responsible for the temperature inversion. We validate our methodology by confirming a previous detection of Fe I in emission at 16.9σ. Our search for the inversion agents TiO, VO, FeH, and CaH results in non-detections. Using injection-recovery testing we set 4σ upper limits upon the volume mixing ratios for these constituents as low as ~1 × 10-9 for TiO. For TiO, VO, and CaH, our limits are much lower than expectations from an equilibrium chemical model, while we cannot set constraining limits on FeH with our data. We thus rule out TiO and CaH as the source of the temperature inversion in KELT-20 b, and VO only if the line lists are sufficiently accurate. *Based on data acquired with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) using the Large Binocular Telescope (LBT) in Arizona.

Keywords: Exoplanet astronomy, Exoplanet atmospheres, Transmission spectroscopy
Discovery of Calm Astronomical Sites Over the Antarctic Continent. A calm astronomical site means a site where astronomical observation would be less likely to be interfered with by optical turbulence. Previous turbulence measurements at a few sites in Antarctica have demonstrated very calm atmospheric conditions here. So far, to realize a wide range of measurements of the turbulence conditions above the Antarctic plateau will be a great hardship. Thus, in this study, the numerical weather model outputs provided by the Antarctic Mesoscale Prediction System (AMPS) have been used. Based on the AMPS outputs, the boundary layer height and the atmospheric Richardson number were obtained, from which the turbulence conditions above the Antarctic plateau have been evaluated. Finally, a statistical conclusion evaluating the total atmospheric turbulence above the whole Antarctic continent for an entire year is first reported. We find some sites (or regions) have a calmer atmosphere than Dome A; this is of great instructional significance for planning the next generation of ground-based optical astronomical telescopes.

Keywords: Atmospheric effects, Astronomical seeing
Absolute Properties of the Oscillating Eclipsing Algol X Trianguli. We report results from the TESS photometric data and new high-resolution spectra of the Algol system X Tri showing short-period pulsations. From the echelle spectra, the radial velocities of the eclipsing pair were measured, and the rotational rate and effective temperature of the primary star were obtained to be v 1sini = 84 ± 6 km s-1 and T eff,1 = 7900 ± 110 K, respectively. The synthetic modeling of these observations implies that X Tri is in synchronous rotation and is physically linked to a visual companion TIC 28391715 at a separation of about 6.″5. The absolute parameters of our target star were accurately and directly determined to be M 1 = 2.137 ± 0.018 M ⊙, M 2 = 1.101 ± 0.010 M ⊙, R 1 = 1.664 ± 0.010 R ⊙, R 2 = 1.972 ± 0.010 R ⊙, L 1 = 9.67 ± 0.55 L ⊙, and L 2 = 2.16 ± 0.09 L ⊙. The phase-binned mean light curve was used to remove the binary effect from the observed TESS data. Multifrequency analysis of the residuals revealed 16 significant frequencies, of which the high-frequency signals between 37 day-1 and 48 day-1 can be considered probable pulsation modes. Their oscillation periods of 0.021-0.027 days and pulsation constants of 0.014-0.018 days are typical values of δ Sct variables. The overall results demonstrate that X Tri is an oEA star system consisting of a δ Sct primary and its lobe-filling companion in the semidetached configuration.

Keywords: Delta Scuti variable stars, Fundamental parameters of stars, Multi-periodic pulsation, Spectroscopy, Eclipsing binary stars, Stellar oscillations, Asteroseismology
Spectroscopic Orbits of Subsystems in Multiple Stars. IX. New spectroscopic orbits of inner subsystems in 14 hierarchies are determined from long-term monitoring with the optical echelle spectrometer, CHIRON. Their main components are nearby solar-type stars belonging to nine triple systems (HIP 3645, 14307, 36165, 79980, 103735, 103814, 104440, 105879, 109443) and five quadruples of 2 + 2 hierarchy (HIP 41171, 49336, 75663, 78163, and 117666). The inner periods range from 254 days to 18 yr. Inner subsystems in HIP 3645, 14313, 79979, 103735, 104440, and 105879 are resolved by speckle interferometry, and their combined spectro-interferometric orbits are derived here. Astrometric orbits of HIP 49336 Aa,Ab and HIP 117666 Aa,Ab are determined from wobble in the observed motion of the outer pairs. Comparison with three spectroscopic orbits found in the Gaia data release 3 archive reveals that Gaia underestimated the amplitudes (except for HIP 109443), while the periods match approximately. This work contributes new data on the architecture of nearby hierarchical systems, complementing their statistics.

Keywords: Spectroscopic binary stars, Multiple stars, Visual binary stars
Exploring the Recycling Model of Phobos Formation: Rubble-pile Satellites. Phobos is the target of the return sample mission Martian Moons eXploration by JAXA that will analyze in great detail the physical and compositional properties of the satellite from orbit, from the surface, and in terrestrial laboratories, giving clues about its formation. Some models propose that Phobos and Deimos were formed after a giant impact giving rise to an extended debris disk. Assuming that Phobos formed from a cascade of disruptions and reaccretions of several parent bodies in this disk, and that they are all characterized by a low material cohesion, Hesselbrock &amp; Minton showed that a recycling process may happen during the assembling of Phobos, by which Phobos's parents are destroyed into a Roche-interior ring and reaccreted several times. In this paper, we explore the recycling model in detail and pay particular attention to the characteristics of the disk using 1D models of disk/satellite interactions. In agreement with previous studies, we confirm that, if Phobos's parent bodies are gravitational aggregates (rubble piles), then the recycling process does occur. However, Phobos should be accompanied today by a Roche-interior ring. Furthermore, the characteristics of the ring are not reconcilable with today's observations of Mars' environment, which put stringent constraints on the existence of a ring around Mars. The recycling mechanism may or may not have occurred at the Roche limit for an old moon population, depending on the internal cohesion. However, the Phobos we see today cannot be the outcome of such a recycling process. * Released on 2023 February 27.

Keywords: Natural satellite formation
Direct Imaging Explorations for Companions around Mid-Late M Stars from the Subaru/IRD Strategic Program. The Subaru telescope is currently performing a strategic program (SSP) using the high-precision near-infrared (NIR) spectrometer IRD to search for exoplanets around nearby mid/late M dwarfs via radial velocity (RV) monitoring. As part of the observing strategy for the exoplanet survey, signatures of massive companions such as RV trends are used to reduce the priority of those stars. However, this RV information remains useful for studying the stellar multiplicity of nearby M dwarfs. To search for companions around such "deprioritized" M dwarfs, we observed 14 IRD-SSP targets using Keck/NIRC2 with pyramid wave-front sensing at NIR wavelengths, leading to high sensitivity to substellar-mass companions within a few arcseconds. We detected two new companions (LSPM J1002+1459 B and LSPM J2204+1505 B) and two new candidates that are likely companions (LSPM J0825+6902 B and LSPM J1645+0444 B), as well as one known companion. Including two known companions resolved by the IRD fiber injection module camera, we detected seven (four new) companions at projected separations between ~2 and 20 au in total. A comparison of the colors with the spectral library suggests that LSPM J2204+1505 B and LSPM J0825+6902 B are located at the boundary between late M and early L spectral types. Our deep high-contrast imaging for targets where no bright companions were resolved did not reveal any additional companion candidates. The NIRC2 detection limits could constrain potential substellar-mass companions (~10-75 M Jup) at 10 au or further. The failure with Keck/NIRC2 around the IRD-SSP stars having significant RV trends makes these objects promising targets for further RV monitoring or deeper imaging with the James Webb Space Telescope to search for smaller-mass companions below the NIRC2 detection limits.

Keywords: M dwarf stars, Brown dwarfs, Direct imaging, Exoplanets
Galactic Model Parameters and Spatial Density of Cataclysmic Variables in the Gaia Era: New Constraints on Population Models. The spatial distribution, Galactic model parameters, and luminosity function of cataclysmic variables (CVs) are established using reestimated trigonometric parallaxes from Gaia DR3. The data sample of 1587 CVs in this study is claimed to be suitable for Galactic model parameter estimation as the distances are based on trigonometric parallaxes, and the Gaia DR3 photometric completeness limits were taken into account when the sample was created. According to the analysis, the scale height of all CVs increases from 248 ± 2 to 430 ± 4 pc toward shorter periods near the lower limit of the period gap and suddenly drops to 300 ± 2 pc for the shortest orbital period CVs. The exponential scale heights of all CVs and the magnetic systems are found to be 375 ± 2 and 281 ± 3 pc, respectively, considerably larger than those suggested in previous observational studies. The local spatial density of all CVs and the magnetic systems in the sample are ${6.8}_{-1.1}^{+1.3}\times $ 10-6 and ${2.1}_{-0.4}^{+0.5}\times {10}^{-6}$ pc-3, respectively. Our measurements strengthen the 1-2 order of magnitude discrepancy between the CV spatial densities predicted by population synthesis models and observations. It is likely that this discrepancy is due to objects undetected by CV surveys, such as systems with very low $\dot{M}$ and ones in the period gap. A comparison of the luminosity function of white dwarfs with the luminosity function of all CVs in this study show that 500 times the luminosity function of CVs fits very well to the luminosity function of white dwarfs. We conclude that the estimations and data sample in this study can be confidently used for further analyses of CVs.

Keywords: Galaxy disks, Cataclysmic variable stars
Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments Are Common. The orientation between a star's spin axis and a planet's orbital plane provides valuable information about the system's formation and dynamical history. For non-transiting planets at wide separations, true stellar obliquities are challenging to measure, but lower limits on spin-orbit orientations can be determined from the difference between the inclination of the star's rotational axis and the companion's orbital plane (Δi). We present results of a uniform analysis of rotation periods, stellar inclinations, and obliquities of cool stars (SpT ≳ F5) hosting directly imaged planets and brown dwarf companions. As part of this effort, we have acquired new $v\sin {i}_{* }$ values for 22 host stars with the high-resolution Tull spectrograph at the Harlan J. Smith telescope. Altogether our sample contains 62 host stars with rotation periods, most of which are newly measured using light curves from the Transiting Exoplanet Survey Satellite. Among these, 53 stars have inclinations determined from projected rotational and equatorial velocities, and 21 stars predominantly hosting brown dwarfs have constraints on Δi. Eleven of these (52 ${}_{-11}^{+10}$ % of the sample) are likely misaligned, while the remaining 10 host stars are consistent with spin-orbit alignment. As an ensemble, the minimum obliquity distribution between 10 and 250 au is more consistent with a mixture of isotropic and aligned systems than either extreme scenario alone-pointing to direct cloud collapse, formation within disks bearing primordial alignments and misalignments, or architectures processed by dynamical evolution. This contrasts with stars hosting directly imaged planets, which show a preference for low obliquities. These results reinforce an emerging distinction between the orbits of long-period brown dwarfs and giant planets in terms of their stellar obliquities and orbital eccentricities.

Keywords: Stellar rotation, Brown dwarfs, Extrasolar gaseous giant planets, Planet formation
Dynamics of Four Triple Systems. Orbital motions in four hierarchical stellar systems discovered by speckle interferometry are studied. Their inner orbits are relatively well constrained, while the long outer orbits are less certain. The eccentric and misaligned inner orbits in the early-type hierarchies ϵ Cha (B9V, central star of the 5 Myr old association, P = 6.4 yr, e = 0.73) and I 385 (A0V, P ~ 300 yr, e ~ 0.8) suggest past dynamical interactions. Their nearly equal masses could be explained by a dynamical decay of a 2+2 quadruple progenitor consisting of four similar stars. However, there is no evidence of the associated recoil, so similar masses could be just a consequence of accretion from the same core. The other two hiearchies, HIP 32475 (F0IV, inner period 12.2 yr) and HIP 42910 (K7V, inner period 6.8 yr), have smaller masses and are double twins where both inner and outer mass ratios are close to one. A double twin could either result from a merger of one inner pair in a 2+2 quadruple or can be formed by a successive fragmentation followed by accretion.

Keywords: Multiple stars, Binary stars
JWST's PEARLS: Dust Attenuation and Gravitational Lensing in the Backlit-galaxy System VV 191. We derive the spatial and wavelength behavior of dust attenuation in the multiple-armed spiral galaxy VV 191b using backlighting by the superimposed elliptical system VV 191a in a pair with an exceptionally favorable geometry for this measurement. Imaging using the James Webb Space Telescope and Hubble Space Telescope spans the wavelength range 0.3-4.5 μm with high angular resolution, tracing the dust in detail from 0.6-1.5 μm. Distinct dust lanes continue well beyond the bright spiral arms, and trace a complex web, with a very sharp radial cutoff near 1.7 Petrosian radii. We present attenuation profiles and coverage statistics in each band at radii 14-21 kpc. We derive the attenuation law with wavelength; the data both within and between the dust lanes clearly favor a stronger reddening behavior (R = A  V /E  B-V  ≈ 2.0 between 0.6 and 0.9 μm, approaching unity by 1.5 μm) than found for starbursts and star-forming regions of galaxies. Power-law extinction behavior ∝λ -β  gives β = 2.1 from 0.6-0.9 μm. R decreases at increasing wavelengths (R ≈ 1.1 between 0.9 and 1.5 μm), while β steepens to 2.5. Mixing regions of different column density flattens the wavelength behavior, so these results suggest a different grain population than in our vicinity. The NIRCam images reveal a lens arc and counterimage from a background galaxy at z ≈ 1, spanning 90° azimuthally at 2.″8 from the foreground elliptical-galaxy nucleus, and an additional weakly lensed galaxy. The lens model and imaging data give a mass/light ratio M/L  B  = 7.6 in solar units within the Einstein radius 2.0 kpc.

Keywords: Strong gravitational lensing, Spiral galaxies, Interstellar dust extinction
TOI-1695 b: A Water World Orbiting an Early-M Dwarf in the Planet Radius Valley. Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass-loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early-M dwarf (T mag = 11.0294 ± 0.0074, M  s  = 0.513 ± 0.012 M ⊙, R  s  = 0.515 ± 0.015 R ⊙, and T eff = 3690 ± 50 K): TOI-1695 b (P = 3.13 days and ${R}_{p}={1.90}_{-0.14}^{+0.16}\ {R}_{\oplus }$ ). TOI-1695 b's radius and orbital period situate the planet between model predictions from thermally driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early-M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of 6.36 ± 1.00 M ⊕, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally driven mass-loss scenario is unlikely to explain this population.

Keywords: M dwarf stars, Stellar properties, Exoplanets, Exoplanet evolution, Transit photometry, Radial velocity, Exoplanet formation, Planet formation, Exoplanet atmospheric evolution
The Demographics of Terrestrial Planets in the Venus Zone. Understanding the physical characteristics of Venus, including its atmosphere, interior, and its evolutionary pathway with respect to Earth, remains a vital component for terrestrial planet evolution models and the emergence and/or decline of planetary habitability. A statistical strategy for evaluating the evolutionary pathways of terrestrial planets lies in the atmospheric characterization of exoplanets, where the sample size provides sufficient means for determining required runaway greenhouse conditions. Observations of potential exo-Venuses can help confirm hypotheses about Venus's past, as well as the occurrence rate of Venus-like planets in other systems. Additionally, the data from future Venus missions, such as DAVINCI, EnVision, and VERITAS, will provide valuable information regarding Venus, and the study of exo-Venuses will be complimentary to these missions. To facilitate studies of exo-Venus candidates, we provide a catalog of all confirmed terrestrial planets in the Venus zone, including transiting and nontransiting cases, and quantify their potential for follow-up observations. We examine the demographics of the exo-Venus population with relation to stellar and planetary properties, such as the planetary radius gap. We highlight specific high-priority exo-Venus targets for follow-up observations, including TOI-2285 b, LTT 1445 A c, TOI-1266 c, LHS 1140 c, and L98-59 d. We also discuss follow-up observations that may yield further insight into the Venus/Earth divergence in atmospheric properties.

Keywords: Observational astronomy, Exoplanet catalogs, Exoplanets, Venus, Exoplanet systems, Exoplanet astronomy, Exoplanet atmospheres