Sazuna/UAT_keywords huggingface dataset:
CD -27°11535: Evidence for a Triple System in the β Pictoris Moving Group. We present new spatially resolved astrometry and photometry of the CD -27°11535 system, a member of the β Pictoris moving group consisting of two resolved K-type stars on a ~20 yr orbit. We fit an orbit to relative astrometry measured from NIRC2, GPI, and archival NaCo images, in addition to literature measurements. However, the total mass inferred from this orbit is significantly discrepant from that inferred from stellar evolutionary models using the luminosity of the two stars. We explore two hypotheses that could explain this discrepant mass sum: a discrepant parallax measurement from Gaia due to variability, and the presence of an additional unresolved companion to one of the two components. We find that the ~20 yr orbit could not bias the parallax measurement, but that variability of the components could produce a large-amplitude astrometric motion, an effect that cannot be quantified exactly without the individual Gaia measurements. The discrepancy could also be explained by an additional star in the system. We jointly fit the astrometric and photometric measurements of the system to test different binary and triple architectures for the system. Depending on the set of evolutionary models used, we find an improved goodness of fit for a triple system architecture that includes a low-mass (M = 0.177 ± 0.055 M ☉) companion to the primary star. Further studies of this system will be required in order to resolve this discrepancy, either by refining the parallax measurement with a more complex treatment of variability-induced astrometric motion or by detecting a third companion.

Keywords: Multiple stars, Young stellar objects, Astrometry, Stellar masses, Orbit determination
A Lithium Depletion Age for the Carina Association. The dispersed remnants of stellar nurseries, stellar associations, provide unparalleled samples of coeval stars critical for studies of stellar and planetary formation and evolution. The Carina Stellar Association is one of the closest stellar associations to Earth, and yet measurements of its age have varied from 13 to 45 Myr. We aim to update the age of Carina using the lithium depletion boundary (LDB) method. We obtain new measurements of the Li 6708 Å absorption feature in likely members using optical spectra from the Goodman High Throughput Spectrograph on SOAR and NRES on LCO. We detect the depletion boundary at M  K  ≃ 6.8 (M5). This age is consistent within uncertainties across six different models, including those that account for magnetic fields and spots. We also estimate the age through analysis of the group's overall variability, and by comparing the association members' color-magnitude diagram to stellar evolutionary models using a Gaussian Mixture Model, recovering ages consistent with the LDB. Combining these age measures we obtain an age for the Carina association of ${41}_{-5}^{+3}$ Myr. The resulting age agrees with the older end of previous age measurements and is consistent with the lithium depletion age for the neighboring Tucana-Horologium moving group.

Keywords: M dwarf stars, Stellar associations
Scaling K2. VII. Evidence For a High Occurrence Rate of Hot Sub-Neptunes at Intermediate Ages. The NASA K2 mission obtained high-precision time-series photometry for four young clusters, including the near-twin 600-800 Myr old Praesepe and Hyades clusters. Hot sub-Neptunes are highly prone to mass-loss mechanisms, given their proximity to the host star and the weakly bound gaseous envelopes, and analyzing this population at young ages can provide strong constraints on planetary evolution models. Using our automated transit detection pipeline, we recover 15 planet candidates across the two clusters, including 10 previously confirmed planets. We find a hot sub-Neptune occurrence rate of 79%-107% for GKM stars in the Praesepe cluster. This is 2.5-3.5σ higher than the occurrence rate of ${16.54}_{-0.98}^{+1.00}$ % for the same planets orbiting the ~3-9 Gyr old GKM field stars observed by K2, even after accounting for the slightly supersolar metallicity ([Fe/H] ~ 0.2 dex) of the Praesepe cluster. We examine the effect of adding ~100 targets from the Hyades cluster and extending the planet parameter space under examination, and we find similarly high occurrence rates in both cases. The high occurrence rate of young, hot sub-Neptunes could indicate either that these planets are undergoing atmospheric evolution as they age, or that planetary systems that formed when the Galaxy was much younger are substantially different than from today. Under the assumption of the atmospheric mass-loss scenario, a significantly higher occurrence rate of these planets at the intermediate ages of Praesepe and Hyades appears more consistent with the core-powered mass-loss scenario for the origin of the planet radius valley, compared to the photoevaporation scenario.

Keywords: Exoplanets, Exoplanet atmospheric evolution
The Far Side of the Galactic Bar/Bulge Revealed through Semi-regular Variables. The Galactic bulge is critical to our understanding of the Milky Way. However, due to the lack of reliable stellar distances, the structure and kinematics of the bulge/bar beyond the Galactic center have remained largely unexplored. Here, we present a method to measure distances of luminous red giants using a period-amplitude-luminosity relation anchored to the Large Magellanic Cloud, with random uncertainties of 10%-15% and systematic errors below 1%-2%. We apply this method to data from the Optical Gravitational Lensing Experiment to measure distances to 190,302 stars in the Galactic bulge and beyond out to 20 kpc. Using this sample, we measure a distance to the Galactic center of R 0 = 8108 ± 106stat ± 93sys pc, consistent with direct measurements of stars orbiting Sgr A*. We cross-match our distance catalog with Gaia DR3 and use the subset of 39,566 overlapping stars to provide the first constraints on the Milky Way's velocity field (V  R , V  ϕ , V  z ) beyond the Galactic center. We show that the V  R  quadrupole from the bar's near side is reflected with respect to the Galactic center, indicating that the bar is bisymmetric and aligned with the inner disk. We also find that the vertical height V  Z  map has no major structure in the region of the Galactic bulge, which is inconsistent with a current episode of bar buckling. Finally, we demonstrate with N-body simulations that distance uncertainty plays a factor in the alignment of the major and kinematic axes of the bar, necessitating caution when interpreting results for distant stars.

Keywords: Galactic archaeology, Asteroseismology, Galactic bulge
Bringing 2D Eclipse Mapping out of the Shadows with Leave-one-out Cross Validation. Eclipse mapping is a technique for inferring 2D brightness maps of transiting exoplanets from the shape of an eclipse light curve. With JWST's unmatched precision, eclipse mapping is now possible for a large number of exoplanets. However, eclipse mapping has only been applied to two planets, and the nuances of fitting eclipse maps are not yet fully understood. Here, we use Leave-one-out Cross Validation (LOO-CV) to investigate eclipse mapping, with application to a JWST NIRISS/SOSS observation of the ultrahot Jupiter WASP-18b. LOO-CV is a technique that provides insight into the out-of-sample predictive power of models on a data-point-by-data-point basis. We show that constraints on planetary brightness patterns behave as expected, with large-scale variations driven by the phase-curve variation in the light curve and smaller-scale structures constrained by the eclipse ingress and egress. For WASP-18b we show that the need for higher model complexity (smaller-scale features) is driven exclusively by the shape of the eclipse ingress and egress. We use LOO-CV to investigate the relationship between planetary brightness map components when mapping under a positive-flux constraint to better understand the need for complex models. Finally, we use LOO-CV to understand the degeneracy between the competing "hot spot" and "plateau" brightness map models of WASP-18b, showing that the plateau model is driven by the ingress shape and the hot spot model is driven by the egress shape, but preference for neither model is due to outliers or unmodeled signals. Based on this analysis, we make recommendations for the use of LOO-CV in future eclipse-mapping studies.

Keywords: Exoplanets, Hot Jupiters, Exoplanet astronomy, Extrasolar gaseous planets, Exoplanet atmospheres, Exoplanet atmospheric structure
Wavelet Transforms of Microlensing Data: Denoising, Extracting Intrinsic Pulsations, and Planetary Signals. Wavelets are waveform functions that describe transient and unstable variations, such as noise. In this work, we study the advantages of discrete and continuous wavelet transforms (DWTs and CWTs) of microlensing data to denoise them and extract their planetary signals and intrinsic pulsations hidden by noise. We first generate synthetic microlensing data and apply wavelet denoising to them. For these simulated microlensing data with ideally Gaussian noise based on the Optical Gravitational Lensing Experiment (OGLE) photometric accuracy, denoising with DWTs reduces standard deviations of data from real models by 0.044-0.048 mag. The efficiency to regenerate real models and planetary signals with denoised data strongly depends on the observing cadence and decreases from 37% to 0.01% with increasing cadence from 15 min to 6 hr. We then apply denoising on 100 microlensing events discovered by the OGLE group. On average, wavelet denoising for these data improves standard deviations and ${\chi }_{n}^{2}$ of data with respect to the best-fit models by 0.023 mag and 1.16, respectively. The best-performing wavelets (based on the highest signal-to-noise ratio's peak ( ${\rm{S}}/{{\rm{N}}}_{\max }$ ), the highest Pearson's correlation, or the lowest root mean squared error for denoised data) are from the Symlet and Biorthogonal wavelet families in simulated and OGLE data, respectively. In some denoised data, intrinsic stellar pulsations or small planetary like deviations appear that were covered with noise in raw data. However, through DWT denoising rather flattened and wide planetary signals could be reconstructed rather than sharp signals. CWTs and 3D frequency-power-time maps could inform about the existence of sharp signals.

Keywords: Exoplanet detection methods, Gravitational microlensing exoplanet detection, Wavelet analysis, Stellar pulsations
OGLE-2019-BLG-1180Lb: Discovery of a Wide-orbit Jupiter-mass Planet around a Late-type Star. We report on the discovery and analysis of the planetary microlensing event OGLE-2019-BLG-1180 with a planet-to-star mass ratio q ~ 0.003. The event OGLE-2019-BLG-1180 has unambiguous cusp-passing and caustic-crossing anomalies, which were caused by a wide planetary caustic with s ≃ 2, where s is the star-planet separation in units of the angular Einstein radius θ E. Thanks to well-covered anomalies by the Korea Micorolensing Telescope Network (KMTNet), we measure both the angular Einstein radius and the microlens parallax in spite of a relatively short event timescale of t E = 28 days. However, because of a weak constraint on the parallax, we conduct a Bayesian analysis to estimate the physical lens parameters. We find that the lens system is a super-Jupiter-mass planet of ${M}_{{\rm{p}}}={1.75}_{-0.51}^{+0.53}\,{M}_{{\rm{J}}}$ orbiting a late-type star of ${M}_{{\rm{h}}}={0.55}_{-0.26}^{+0.27}\,{M}_{\odot }$ at a distance ${D}_{{\rm{L}}}={6.1}_{-1.3}^{+0.9}\,\mathrm{kpc}$ . The projected star-planet separation is ${a}_{\perp }={5.19}_{-1.23}^{+0.90}\,\mathrm{au}$ , which means that the planet orbits at about four times the snow line of the host star. Considering the relative lens-source proper motion of μ rel = 6 mas yr-1, the lens will be separated from the source by 60 mas in 2029. At that time one can measure the lens flux from adaptive optics imaging of Keck or a next-generation 30 m class telescope. OGLE-2019-BLG-1180Lb represents a growing population of wide-orbit planets detected by KMTNet, so we also present a general investigation into prospects for further expanding the sample of such planets.

Keywords: Gravitational microlensing, Exoplanet detection methods, Gravitational microlensing exoplanet detection
Constraining Background N<SUB>2</SUB> Inventories on Directly Imaged Terrestrial Exoplanets to Rule Out O<SUB>2</SUB> False Positives. Direct imaging spectroscopy with future space-based telescopes will constrain terrestrial planet atmospheric composition and potentially detect biosignature gases. One promising indication of life is abundant atmospheric O2. However, various non-biological processes could also lead to O2 accumulation in the atmospheres of potentially habitable planets around Sun-like stars. In particular, the absence of non-condensible background gases such as N2 could result in appreciable H escape and abiotic O2 buildup, so identifying background atmosphere composition is crucial for contextualizing any O2 detections. Here, we perform retrievals on simulated directly imaged terrestrial planets using rfast, a new exoplanet atmospheric retrieval suite with direct imaging analysis capabilities. By simulating Earth-analog retrievals for varied atmospheric compositions, cloud properties, and surface pressures, we determine what wavelength range, spectral resolution, and signal-to-noise ratio (S/N) are necessary to constrain background gases' identity and abundance. We find N2 backgrounds can be uniquely identified with S/N ~ 20 observations, provided that wavelength coverage extends beyond ~1.6 μm to rule out CO-dominated atmospheres. Additionally, there is a low probability of O2-dominated atmospheres due to an O2-N2 degeneracy that is only totally ruled out at S/N ~ 40. If wavelength coverage is limited to 0.2-1.1 μm, then although all other cosmochemically plausible backgrounds can be readily excluded, N2 and CO backgrounds cannot be distinguished. Overall, our simulated retrievals and associated integration time calculations suggest that near-infrared coverage to at least 1.6 μm and apertures approaching 8 m are needed to confidently rule out O2 biosignature false positives within feasible integration times.

Keywords: Telescopes, Astrobiology, Exoplanet atmospheres, Spectroscopy
Considering the Single and Binary Origins of the Type IIP SN 2017eaw. Current population synthesis modeling suggests that 30%-50% of Type II supernovae originate from binary progenitors; however, the identification of a binary progenitor is challenging. One indicator of a binary progenitor is that the surrounding stellar population is too old to contain a massive single star. Measurements of the progenitor mass of SN 2017eaw are starkly divided between observations made temporally close to core collapse, which show a progenitor mass of 13-15 M ⊙ (final helium-core mass ${M}_{\mathrm{He},\mathrm{core}}=4.4\mbox{--}6.0\,{M}_{\odot }$ -which is a more informative property than initial mass) and those from the stellar population surrounding the SN, which find M ≤ 10.8 M ⊙ ( ${M}_{\mathrm{He},\mathrm{core}}\leqslant 3.4\,{M}_{\odot }$ ). In this paper, we reanalyze the surrounding stellar population with improved astrometry and photometry, finding a median age of ${16.8}_{-1.0}^{+3.2}$ Myr for all stars younger than 50 Myr ( ${M}_{\mathrm{He},\mathrm{core}}=4.7{M}_{\odot }$ ) and ${85.9}_{-6.5}^{+3.2}$ Myr for stars younger than 150 Myr. 16.8 Myr is now consistent with the helium-core mass range derived from the temporally near-explosion observations for single stars. Applying the combined constraints to population synthesis models, we determine that the probability of the progenitor of SN 2017eaw being an initially single star is 65% compared to 35% for prior binary interaction. 85.9 Myr is inconsistent with any formation scenarios. We demonstrate that combining progenitor age constraints with helium-core mass estimates from red supergiant SED modeling, late-time spectra, and indirectly from light-curve modeling can help to differentiate single and binary progenitor scenarios and provide a framework for the application of this technique to future observations.

Keywords: Binary stars, Late stellar evolution, Stellar populations, Type II supernovae, Massive stars, Stellar evolutionary models
The Advantages of Global Photometric Models in Fitting Transit Variations. Estimation of planetary orbital and physical parameters from light-curve data relies heavily on the accurate interpretation of Transit Timing Variation (TTV) measurements. In this letter, we review the process of TTV measurement and compare two fitting paradigms-one that relies on making transit-by-transit timing estimates and then fitting a TTV model to the observed timings, and one that relies on fitting a global flux model to the entire light-curve data set simultaneously. The latter method is achieved either by solving for the underlying planetary motion (often referred to as "photodynamics"), or by using an approximate or empirical shape of the TTV signal. We show that, across a large range of the transit S/N regime, the probability distribution function of the mid-transit time significantly deviates from a Gaussian, even if the flux errors do distribute normally. Treating the timing uncertainties as if they are distributed normally leads, in such a case, to a wrong interpretation of the TTV measurements. We illustrate these points using numerical experiments and conclude that a fitting process that relies on a global flux fitting, rather than the derived TTVs, should be preferred.

Keywords: Light curves, Transit timing variation method, Exoplanets
First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity. Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best-fit ExoREM model with solar metallicity and C/O = 0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available on GitHub: https://github.com/sblunt/hip65426.

Keywords: Optical interferometry, Exoplanet formation, Astrometry, Exoplanets
Detecting Solar System Analogs through Joint Radial Velocity/Astrometric Surveys. Earth-mass exoplanets on year-long orbits and cool gas giants (CGG) on decade-long orbits lie at the edge of current detection limits. The Terra Hunting Experiment (THE) will take nightly radial velocity (RV) observations on HARPS3 of at least 40 bright nearby G and K dwarfs for 10 yr, with a target 1σ measurement error of ~0.3 m s-1, in search of exoplanets that are Earth-like in mass and temperature. However, RV observations can only provide minimum mass estimates, due to the mass-inclination degeneracy. Astrometric observations of these same stars, with sufficient precision, could break this degeneracy. Gaia will soon release ~100-200 astrometric observations of the THE stars with a 10 yr baseline and ~34.2 μas 1σ along-scan measurement error. The Nancy Grace Roman Space Telescope will be capable of precision astrometry using its wide field imager (target ~5-20 μas 1σ measurement error for bright stars) and could extend the astrometric observational baseline to ~25 yr. We simulate and model an observing program that combines data from these three telescopes. We find that (1) THE RVs and Gaia astrometry can detect Earth-like and CGG-like exoplanets around bright Sun-like stars at 10 pc and that (2) adding Roman astrometry improves the detection precision for CGG masses and periods by respective factors up to ~10 and ~4. Such a survey could provide insight into the prevalence of Solar System analogs, exoplanet architectures reminiscent of the mass and orbital separation hierarchy of our Solar System, for the nearest Sun-like stars.

Keywords: Extrasolar rocky planets, Solar system planets, Radial velocity, Extrasolar gaseous planets, Space astrometry, Exoplanet detection methods
Survey Operations for the Dark Energy Spectroscopic Instrument. The Dark Energy Spectroscopic Instrument (DESI) survey is a spectroscopic survey of tens of millions of galaxies at 0 &lt; z &lt; 3.5 covering 14,000 sq. deg. of the sky. In its first 1.1 yr of survey operations, it has observed more than 14 million galaxies and 4 million stars. We describe the processes that govern DESI's observations of the 15,000 fields composing the survey. This includes the planning of each night's observations in the afternoon; automatic selection of fields to observe during the night; real-time assessment of field completeness on the basis of observing conditions during each exposure; reduction, redshifting, and quality assurance of each field of targets in the morning following observation; and updates to the list of future targets to observe on the basis of these results. We also compare the performance of the survey with historical expectations and find good agreement. Simulations of the weather and of DESI observations using the real field-selection algorithm show good agreement with the actual observations. After accounting for major unplanned shutdowns, the dark time survey is progressing about 7% faster than forecast, which is good agreement given approximations made in the simulations.

Keywords: Observatories, Redshift surveys, Spectroscopy
A Wolf 359 in Sheep's Clothing: Hunting for Substellar Companions in the Fifth-closest System Using Combined High-contrast Imaging and Radial Velocity Analysis. Wolf 359 (CN Leo, GJ 406, Gaia DR3 3864972938605115520) is a low-mass star in the fifth-closest neighboring system (2.41 pc). Because of its relative youth and proximity, Wolf 359 offers a unique opportunity to study substellar companions around M stars using infrared high-contrast imaging and radial velocity monitoring. We present the results of Ms-band (4.67 μm) vector vortex coronagraphic imaging using Keck-NIRC2 and add 12 Keck-HIRES and 68 MAROON-X velocities to the radial velocity baseline. Our analysis incorporates these data alongside literature radial velocities from CARMENES, the High Accuracy Radial velocity Planet Searcher, and Keck-HIRES to rule out the existence of a close (a &lt; 10 au) stellar or brown dwarf companion and the majority of large gas giant companions. Our survey does not refute or confirm the long-period radial velocity candidate, Wolf 359 b (P ~ 2900 days), but rules out the candidate's existence as a large gas giant (&gt;4 M Jup) assuming an age of younger than 1 Gyr. We discuss the performance of our high-contrast imaging survey to aid future observers using Keck-NIRC2 in conjunction with the vortex coronagraph in the Ms band and conclude by exploring the direct imaging capabilities with JWST to observe Jupiter- and Neptune-mass planets around Wolf 359.

Keywords: Exoplanets, M stars, Coronagraphic imaging, Cold Neptunes, Direct imaging, Radial velocity