Sazuna/UAT_keywords huggingface dataset:
M67 Blue Stragglers with High-resolution Infrared Spectroscopy. We report on the first detailed infrared chemical analysis of five binary members (S277, S997, S975, S1031, and S1195) in the open cluster M67 (NGC 2682). These stars are located outside (bluer and/or brighter than) the main-sequence turnoff region in M67. High-resolution (R ~ 45,000) near-infrared spectra were obtained with the Immersion GRating INfrared Spectrograph (IGRINS) at the McDonald Observatory 2.7 m Harlan J. Smith Telescope, providing full spectral coverage of the H and K bands. The abundances of C, Na, Mg, Al, Si, S, Ca, Fe, and Ni are measured using neutral atomic absorption lines. We detect v sin i ≥ 25 km s-1 in three of our program stars: S1031, S975, and S1195. We find our derived abundances to be in good agreement with turnoff star abundances, similar to published analyses of blue straggler stars in M67 from optical spectra. Detection of a carbon enhancement or depletion resulting from mass transfer is difficult due to the uncertainties in the carbon abundance and the relatively modest changes that may occur through red giant and asymptotic giant branch evolution.

Keywords: Blue straggler stars, Open star clusters, Stellar abundances
A Nondetection of Iron in the First High-resolution Emission Study of the Lava Planet 55 Cnc e. Close-in lava planets represent an extreme example of terrestrial worlds, but their high temperatures may allow us to probe a diversity of crustal compositions. The brightest and most well-studied of these objects is 55 Cancri e, a nearby super-Earth with a remarkably short 17 hr orbit. However, despite numerous studies, debate remains about the existence and composition of its atmosphere. We present upper limits on the atmospheric pressure of 55 Cnc e derived from high-resolution time-series spectra taken with Gemini-N/MAROON-X. Our results are consistent with current crustal evaporation models for this planet which predict a thin ~100 mbar atmosphere. We conclude that, if a mineral atmosphere is present on 55 Cnc e, the atmospheric pressure is below 100 mbar.

Keywords: Observational astronomy, Exoplanet atmospheres
Active Asteroid 311P/PanSTARRS: Rotational Instability as the Origin of its Multitails?. The active asteroid 311P/PanSTARRS is one of the two targets of the planned Chinese asteroid exploration mission Tianwen-2. During 2013, 311P experienced several mass-loss events and exhibited multiple comet-like tails. Here we analyze the morphology and surface brightness of the tails to investigate the dust environment around the nucleus and the mechanism of activities. We enhance the features of the tails using image processing techniques to obtain information about the morphologies of the tails, and fit the processed images with syndyne-synchrone diagrams. The fitting results give estimations of the upper limits of the durations (2-8 days) of eruptions and the dust size ranges (0.006 -38.9 mm) in the tails. The results of surface photometry performed for each dust tail show that the brightness distribution index of each tail ranged from approximately -1.81 to 0 and the dust size distribution indices of 311P's tails ranged from -2.29 to -1.45. The quantity of particles in each tail ranged from 0.5 to 8 × 106 kg, which leads to a total dust-loss quantity of 3.0 × 107 kg and a mass-loss rate of 1.59 kg s-1. Sublimation, continuous impacts, or tidal forces of planets are excluded as explanations for 311P's activities, and rotational instability remains a possible activation cause without strong evidence against it.

Keywords: Main belt asteroids, Comet dust tails
Reflected Spectroscopy of Small Exoplanets. III. Probing the UV Band to Measure Biosignature Gases. Direct-imaging observations of terrestrial exoplanets will enable their atmospheric characterization and habitability assessment. Considering Earth, the key atmospheric signatures for the biosphere are O2 and the photochemical product O3. However, this O2-O3 biosignature is not detectable in the visible wavelengths for most of the time after the emergence of oxygenic photosynthesis life (i.e., Proterozoic Earth). Here we demonstrate spectroscopic observations in the ultraviolet wavelengths for detecting and characterizing O2 and O3 in Proterozoic-Earth-like planets, using EXOREL ${}^{{\mathfrak{R}}}$ . For an O2 mixing ratio 2-3 orders of magnitude less than the present-day Earth and an O3 mixing ratio of 10-7 to 10-6, we find that O3 can be detected and its mixing ratio can be measured precisely (within 1 order of magnitude) in the ultraviolet (0.25-0.4 μm), in addition to visible-wavelength spectroscopy. With modest spectral resolution (R = 7) and signal-to-noise ratio (~10) in the ultraviolet, the O3 detection is robust against other potential gases absorbing in the ultraviolet (e.g., H2S and SO2), as well as the short-wavelength cutoff between 0.2 and 0.25 μm. While the O3 detection does not rely on the near-infrared spectra, extending the wavelength coverage to the near-infrared (1-1.8 μm) would provide essential information to interpret the O3 biosignature, including the mixing ratio of H2O, the cloud pressure, and the determination of the dominant gas of the atmosphere. The ultraviolet and near-infrared capabilities should thus be evaluated as critical components for future missions aiming at imaging and characterizing terrestrial exoplanets, such as the Habitable Worlds Observatory.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric composition , Bayesian statistics, Posterior distribution, Bayes' Theorem, Prior distribution, Exoplanet atmospheres
Characterizing a World Within the Hot-Neptune Desert: Transit Observations of LTT 9779 b with the Hubble Space Telescope/WFC3. We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot-Neptune desert, that has been observed with Hubble Space Telescope (HST)/WFC3 with G102 and G141. The combined transmission spectrum, which covers 0.8-1.6 μm, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H2O, CO2, and FeH with a significance of 3.1σ, 2.4σ, and 2.1σ, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 μm helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which are not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyα.

Keywords: Hot Neptunes, Hubble Space Telescope, Infrared spectroscopy, Exoplanets
The Orbit of Warm Jupiter WASP-106 b is Aligned with its Star. Understanding orbital obliquities, or the misalignment angles between a star's rotation axis and the orbital axis of its planets, is crucial for unraveling the mechanisms of planetary formation and migration. In this study, we present an analysis of Rossiter-McLaughlin (RM) observations of the warm Jupiter exoplanet WASP-106 b. The high-precision radial velocity measurements were made with HARPS and HARPS-N during the transit of this planet. We aim to constrain the orientation of the planet's orbit relative to its host star's rotation axis. The RM observations are analyzed using a code which models the RM anomaly together with the Keplerian orbit given several parameters in combination with a Markov chain Monte Carlo implementation. We measure the projected stellar obliquity in the WASP-106 system for the first time and find λ = (-1 ± 11)°, supporting the theory of quiescent migration through the disk.

Keywords: Exoplanet migration, Transits, Exoplanet evolution, Photometry, Radial velocity
False Planets around Giant Stars: A Case Study of Sanders 364 in M67. Discovering planets in sparsely populated regions of parameter space is crucial to improving our understanding of planetary formation and evolution. One such region is the subset of planets that orbit giant, evolved stars. However, some of these evolved stars are known to exhibit long-period quasiperiodic radial velocity signals, which can masquerade as signals from orbital motion due to planetary companions. In this paper, we investigate the case of Sanders 364, a K giant star in the old open cluster M67. A paper by Brucalassi et al. reports the discovery of a giant planet with a period of 121 days orbiting Sanders 364. From our analysis of a large set of independent radial velocities, we find no convincing evidence for the giant planet reported by Brucalassi et al. We did identify six long-period radial velocity signals of unclear origin, including the 121 days signal reported by Brucalassi et al., but based on our analysis, we speculate that these are quasiperiodic signals that arise from nonplanetary origins, such as stellar variability or aliasing. The results from our study of Sanders 364 suggest that the detection of true orbital motion from a long-period planetary companion requires extra care when the host star is highly evolved. We conclude by offering recommendations for future study of planetary companions around evolved host stars.

Keywords: K giant stars, Radial velocity, Exoplanets
TU Tau B: The Peculiar "Eclipse" of a Possible Proto-barium Giant. TU Tau (=HD 38218 = HIP 27135) is a binary system consisting of a C-N carbon star primary and an A-type secondary. We report on new photometry and spectroscopy which tracked the recent disappearance of the A-star secondary. The dimming of the A star was gradual and irregular, with one or more brief brightenings, implying the presence of nonhomogeneities in the carbon star outflow. We also present evidence that the A star is actively accreting s-process enriched material from the carbon star and suggest that it will therefore eventually evolve into a Barium giant. This is an important system as well because the A-type star can serve as a probe of the outer atmosphere of the carbon star.

Keywords: A stars, Carbon stars, N stars, Eclipsing binary stars, Barium stars, S-process
MagAO-X and HST High-contrast Imaging of the AS209 Disk at Hα. The detection of emission lines associated with accretion processes is a direct method for studying how and where gas giant planets form, how young planets interact with their natal protoplanetary disk, and how volatile delivery to their atmosphere takes place. Hα (λ = 0.656 μm) is expected to be the strongest accretion line observable from the ground with adaptive optics systems, and is therefore the target of specific high-contrast imaging campaigns. We present MagAO-X and Hubble Space Telescope (HST) data obtained to search for Hα emission from the previously detected protoplanet candidate orbiting AS209, identified through Atacama Large Millimeter/submillimeter Array observations. No signal was detected at the location of the candidate, and we provide limits on its accretion. Our data would have detected an Hα emission with F Hα  &gt; 2.5 ± 0.3 × 10-16 erg s-1 cm-2, a factor 6.5 lower than the HST flux measured for PDS70 b. The flux limit indicates that if the protoplanet is currently accreting it is likely that local extinction from circumstellar and circumplanetary material strongly attenuates its emission at optical wavelengths. In addition, the data reveal the first image of the jet north of the star as expected from previous detections of forbidden lines. Finally, this work demonstrates that current ground-based observations with extreme adaptive optics systems can be more sensitive than space-based observations, paving the way to the hunt for small planets in reflected light with extremely large telescopes.

Keywords: Exoplanet astronomy, Exoplanet detection methods, Exoplanet formation, Direct imaging
TOI 4201 b and TOI 5344 b: Discovery of Two Transiting Giant Planets around M-dwarf Stars and Revised Parameters for Three Others. We present the discovery from the TESS mission of two giant planets transiting M-dwarf stars: TOI 4201 b and TOI 5344 b. We also provide precise radial velocity measurements and updated system parameters for three other M dwarfs with transiting giant planets: TOI 519, TOI 3629, and TOI 3714. We measure planetary masses of 0.525 ± 0.064 M J, 0.243 ± 0.020 M J, 0.689 ± 0.030 M J, 2.57 ± 0.15 M J, and 0.412±0.040 M J for TOI 519 b, TOI 3629 b, TOI 3714 b, TOI 4201 b, and TOI 5344 b, respectively. The corresponding stellar masses are 0.372 ± 0.018 M ☉, 0.635 ± 0.032 M ☉, 0.522 ± 0.028 M ☉, 0.626 ± 0.033 M ☉, and 0.612 ± 0.034 M ☉. All five hosts have supersolar metallicities, providing further support for recent findings that, like for solar-type stars, close-in giant planets are preferentially found around metal-rich M-dwarf host stars. Finally, we describe a procedure for accounting for systematic errors in stellar evolution models when those models are included directly in fitting a transiting planet system.

Keywords: Exoplanet systems
Octofitter: Fast, Flexible, and Accurate Orbit Modeling to Detect Exoplanets. As next-generation imaging instruments and interferometers search for planets closer to their stars, they must contend with increasing orbital motion and longer integration times. These compounding effects make it difficult to detect faint planets but also present an opportunity. Increased orbital motion makes it possible to move the search for planets into the orbital domain, where direct images can be freely combined with the radial velocity and proper motion anomaly, even without a confirmed detection in any single epoch. In this paper, we present a fast and differentiable multimethod orbit-modeling and planet detection code called Octofitter. This code is designed to be highly modular and allows users to easily adjust priors, change parameterizations, and specify arbitrary function relations between the parameters of one or more planets. Octofitter further supplies tools for examining model outputs including prior and posterior predictive checks and simulation-based calibration. We demonstrate the capabilities of Octofitter on real and simulated data from different instruments and methods, including HD 91312, simulated JWST/NIRISS aperture masking interferometry observations, radial velocity curves, and grids of images from the Gemini Planet Imager. We show that Octofitter can reliably recover faint planets in long sequences of images with arbitrary orbital motion. This publicly available tool will enable the broad application of multiepoch and multimethod exoplanet detection, which could improve how future targeted ground- and space-based surveys are performed. Finally, its rapid convergence makes it a useful addition to the existing ecosystem of tools for modeling the orbits of directly imaged planets.

Keywords: Exoplanet detection methods, Direct imaging, Bayesian statistics
A Massive Hot Jupiter Orbiting a Metal-rich Early M Star Discovered in the TESS Full-frame Images. Observations and statistical studies have shown that giant planets are rare around M dwarfs compared with Sun-like stars. The formation mechanism of these extreme systems has remained under debate for decades. With the help of the TESS mission and ground-based follow-up observations, we report the discovery of TOI-4201b, the most massive and densest hot Jupiter around an M dwarf known so far with a radius of 1.22 ± 0.04 R J and a mass of 2.48 ± 0.09 M J, about 5 times heavier than most other giant planets around M dwarfs. It also has the highest planet-to-star mass ratio (q ~ 4 × 10-3) among such systems. The host star is an early M dwarf with a mass of 0.61 ± 0.02 M ☉ and a radius of 0.63 ± 0.02 R ☉. It has significant supersolar iron abundance ([Fe/H] = 0.52 ± 0.08 dex). However, interior structure modeling suggests that its planet TOI-4201b is metal-poor, which challenges the classical core-accretion correlation of stellar-planet metallicity, unless the planet is inflated by additional energy sources. Building on the detection of this planet, we compare the stellar metallicity distribution of four planetary groups: hot/warm Jupiters around G/M dwarfs. We find that hot/warm Jupiters show a similar metallicity dependence around G-type stars. For M-dwarf host stars, the occurrence of hot Jupiters shows a much stronger correlation with iron abundance, while warm Jupiters display a weaker preference, indicating possible different formation histories.

Keywords: M dwarf stars, M stars, Extrasolar gaseous planets, Photometry, Radial velocity
Visual Orbits and Alignments of Planet-hosting Binary Systems. Roughly half of Solar-type planet hosts have stellar companions, so understanding how these binary companions affect the formation and evolution of planets is an important component to understanding planetary systems overall. Measuring the dynamical properties of planet host binaries enables a valuable test of planet formation in multistar systems and requires knowledge of the binary orbital parameters. Using high-resolution imaging, we have measured the relative astrometry and visual orbits of 13 binary systems where one of the stars is known to host a transiting exoplanet. Our results indicate that the mutual inclination between the orbits of the binary hosts and the transiting planets are well aligned. Our results for close binary systems (a &lt; 100 au) complement past work for wide planet host binaries from Gaia.

Keywords: Astrometric binary stars, Binary stars, Exoplanet systems, Planet hosting stars
Asteroseismology and Spectropolarimetry of the Exoplanet Host Star λ Serpentis. The bright star λ Ser hosts a hot Neptune with a minimum mass of 13.6 M ⊕ and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to the Sun. We aim to characterize the fundamental properties of this system and constrain the evolutionary pathway that led to its present configuration. We detect solar-like oscillations in time series photometry from the Transiting Exoplanet Survey Satellite, and we derive precise asteroseismic properties from detailed modeling. We obtain new spectropolarimetric data, and we use them to reconstruct the large-scale magnetic field morphology. We reanalyze the complete time series of chromospheric activity measurements from the Mount Wilson Observatory, and we present new X-ray and ultraviolet observations from the Chandra and Hubble space telescopes. Finally, we use the updated observational constraints to assess the rotational history of the star and estimate the wind braking torque. We conclude that the remaining uncertainty on the stellar age currently prevents an unambiguous interpretation of the properties of λ Ser, and that the rate of angular momentum loss appears to be higher than for other stars with a similar Rossby number. Future asteroseismic observations may help to improve the precision of the stellar age.

Keywords: Spectropolarimetry, Stellar activity, Stellar oscillations, Stellar rotation, Stellar evolution
Modified Newtonian Dynamics as an Alternative to the Planet Nine Hypothesis. A new class of Kuiper Belt objects (KBOs) that lie beyond Neptune with semimajor axes greater than 250 astronomical units show orbital anomalies that have been interpreted as evidence for an undiscovered ninth planet. We show that a modified gravity theory known as modified Newtonian dynamics (MOND) provides an alternative explanation for the anomalies using the well-established secular approximation. We predict that the major axes of the orbits will be aligned with the direction toward the Galactic center and that the orbits cluster in phase space, in agreement with observations of KBOs from the new class. Thus, MOND, which can explain galactic rotation without invoking dark matter, might also be observable in the outer solar system.

Keywords: Modified Newtonian dynamics, Kuiper belt
Most Rotational Variables Dominated by a Single Bright Feature Are α <SUP>2</SUP> CVn Stars. We previously reported a rare class of variable star light curves isolated from a sample of 4.7 million candidate variables from the ATLAS survey. Dubbed "UCBH" light curves, they have broad minima and narrow, symmetrical maxima, with typical periods of 1-10 days and amplitudes of 0.05-0.20 mag. They maintain constant amplitude, shape, and phase coherence over multiple years but do not match any known class of pulsating variables. A localized bright spot near the equator of a rotating star will produce a UCBH-type light curve for most viewing geometries. Most stars that exhibit rotational variability caused primarily by a single bright feature should therefore appear as UCBH stars, although a rotating bright spot is not the only thing that could produce a UCBH-type light curve. We have spectroscopically investigated 14 UCBH stars and found 10 of them to be Ap/Bp stars: A-type or B-type stars with greatly enhanced photospheric abundances of specific heavy elements. Rotationally variable Ap/Bp stars are referred to as α 2 CVn variables. Most ATLAS UCBH stars are therefore α 2 CVn stars, although only a minority of α 2 CVn stars in the literature have UCBH light curves. The fact that α 2 CVn stars dominate the UCBH class suggests that lone bright spots with sufficient size and contrast develop more readily on Ap/Bp stars than on any other type. The α 2 CVn UCBH stars may be characterized by a specific magnetic field topology, making them intriguing targets for future Zeeman-Doppler imaging.

Keywords: Starspots, Silicon stars, Ap stars, Peculiar variable stars, Variable stars, Magnetic variable stars, Stellar rotation, Stellar spectral lines, Chemically peculiar stars
Revisiting Galactic Disk and Spiral Arms Using Open Clusters. We use the largest catalog of open clusters in the post-Gaia era to provide an observational view of the Galactic disk. By compiling physical parameters such as age, distance, and kinematic information, we investigate the spatial distribution of open clusters and revisit the spiral arms and other asymmetries in the Galactic disk. Using young open clusters as a tracer of spiral arms, we map the spiral structure of the Galaxy and find that most of the clusters start migrating away from the spiral arms in about 10-20 Myr and fill the interarm regions as they age. Using the 3D kinematic information on 371 open star clusters, we derive different individual pattern speeds for spiral arms that closely follow the rotation curve of the Milky Way, hence favoring the transient nature of spiral arms in the Milky Way. The pattern rotation speeds of each spiral arm suggest that the spiral arms have not accelerated in the last 80 Myr. Based on the distribution of open clusters younger than 700 Myr above or below the Galactic plane, we found a solar offset of z ⊙ = 17.0 ± 0.9 pc north of the Galactic plane and estimated the scale height z  h  = 91.7 ± 1.9 pc from the Galactic plane.

Keywords: Open star clusters, Milky Way disk, Galaxy structure