Sazuna/UAT_keywords huggingface dataset:
MOA-2010-BLG-328: Keck and HST Expose the Limits of Occams Razor in Microlensing. We present high-resolution follow-up data of the microlensing event MOA-2010-BLG-328, using Keck and the Hubble Space Telescope. Keck data, taken 8 yr after the event, reveal a strong lens detection enabling measurement of lens flux and source-lens relative proper motion. We find μrel,Hel = 4.07 ± 0.34 mas yr−1, with the lens ∼10 times fainter than the source. The lens was very faint in the Hubble passbands, and the small ∼35 mas lens-source separation made its detection difficult. However, we estimated lens magnitudes in Hubble bands by constraining its location to match the Keck K-band detection. K. Furusawa et al. reported a degenerate light curve, with viable models including microlensing parallax and lens orbital motion, or xallarap. We attempt to break this degeneracy by remodeling the event with constraints from high-resolution imaging, but find none of their models fit. Instead, fitting the follow-up data requires microlensing parallax, lens orbital motion, and a magnified binary companion to the host, with xallarap. The high-resolution data do break the "ecliptic degeneracy" common in Galactic bulge microlensing events with parallax signals. Models omitting any of these effects are excluded. However, a new degeneracy allows different combinations of parallax, orbital motion, xallarap, and source companion magnification to explain the light curve. These require either a nearby late M dwarf host or a more distant early M dwarf host, indistinguishable with NIR data alone.

Keywords: Microlensing parallax, Exoplanets, High-resolution microlensing event imaging, Binary lens microlensing, Exoplanet astronomy, Gravitational microlensing, Lens orbital motion, Binary source microlensing
PCA-enhanced Speckle Interferometry with Bicubic Interpolation at the OAN-SPM México. We present an improved methodology for the reduction and analysis of speckle interferometry data, based on observations obtained with the 2.1 m telescope at the Observatorio Astronómico Nacional in Sierra San Pedro Mártir, México. Our approach combines Principal Component Analysis (PCA) filtering with bicubic interpolation to enhance both the signal-to-noise ratio and spatial resolution of the speckle data, while preserving the morphology of the autocorrelation functions. PCA is employed to suppress incoherent noise by reconstructing the speckle cube using only the dominant components, which correspond to consistent features across frames. Bicubic interpolation is then applied to refine the spatial sampling of the reconstructed images. Following these procedures, we apply a binary detection algorithm based on morphological filtering and adaptive threshold masking to identify companion candidates. The method was validated using a sample of 97 binary systems with well-determined orbital solutions. Our results show a substantial improvement in measurement precision: the average uncertainty in angular separation decreased from 10.3 to 4.5 mas, in position angle from  1.°85  to  0.°91 , and in magnitude difference from 0.09 to 0.05 mag—corresponding to average improvements of 56.4%, 51.8%, and 42.6%, respectively. In tangential coordinates, the propagated uncertainty ρσθ exhibits a median reduction of 57.4%, commensurate with the radial uncertainty σρ. These results demonstrate the effectiveness of our technique for increasing the reliability of speckle interferometry measurements, particularly in the context of stellar multiplicity surveys and orbit calibration campaigns.

Keywords: Close binary stars, Principal component analysis, Angular separation, Astrometry, Speckle interferometry, Interferometric binary stars, Visual binary stars
The Interstellar Heritage of Comets. Comets have similar compositions to interstellar medium ices, suggesting at least some of their molecules may be inherited from an earlier stage of evolution. To investigate the degree to which this might have occurred, we compare the composition of individual comets to that of the well-studied protostellar region IRAS 16293─2422B. We show that the observed molecular abundance ratios in several comets correlate well with those observed in the protostellar source. However, this does not necessarily mean that the cometary abundances are identical to protostellar. We find the abundance ratios of many molecules present in comets are enhanced compared to their protostellar counterparts. For COH molecules, the data suggest higher abundances relative to methanol of more complex species, e.g., HCOOH, CH3CHO, and HCOOCH3, are found in comets. For N-bearing molecules, the ratios of nitriles relative to CH3CN—HC3N/CH3CN and HCN/CH3CN—tend to be enhanced. The abundances of cometary SO and SO2 relative to H2S are enhanced, whereas OCS/H2S is reduced. Using a subset of comets with a common set of observed molecules, we suggest a possible means of determining the relative degree to which they retain interstellar ices. This analysis suggests that over 84% of COH-bearing molecules can be explained by the protostellar composition. The possible fraction inherited from the protostellar region is lower for nitrogen molecules, at only 26%─74%. While this is still speculative, especially since few comets have large numbers of observed molecules, it provides a possible route for determining the relative degree to which comets contain disk-processed material.

Keywords: Astrochemistry, Interstellar medium, Protostars, Comets, Comet origins
Aligned Stellar Obliquities for Two Hot Jupiter-hosting M Dwarfs Revealed by MAROON-X: Implications for Hot Jupiter Formation. Hot Jupiters (HJs) are 2─3× less common around M dwarfs than around AFGK stars, suggesting that HJs may form and/or migrate via distinct pathways around different types of stars. One source of insight into HJ formation mechanisms is to trace their dynamical histories through measurements of host stellar obliquities via the Rossiter─McLaughlin (RM) effect. Here we present measurements of the RM effect for the HJs TOI-3714 b and TOI-5293 A b using the Gemini-North/MAROON-X spectrograph. Our measurements represent just the second and third hot Jupiters around M dwarfs (HJMD) with a detection of the RM effect. We find that both systems are well-aligned with sky-projected obliquities of  λ=21−11+14°  and  −12−14+19°  and deprojected obliquities of  ψ=26−10+11°  and  24−10+11°  for TOI-3714 and TOI-5293 A, respectively. Both stars are in wide binary systems. We refine the stellar parameters by decontaminating their unresolved Ks-band photometry and constrain the binary orbits using Gaia DR3 astrometry. We find that the minimum mutual inclination of the planet and binary companion in the TOI-5293 system is sufficiently large to drive Kozai─Lidov (KL) migration, while the result for TOI-3714 is inconclusive. We present a population-level analysis of HJs around AFGK versus early M dwarfs and argue that KL migration is more efficient around the latter, which is expected to produce misaligned stellar obliquities in HJMD systems in the absence of efficient tidal damping. The emerging population of well-aligned HJMD hosts supports the expectation that M dwarfs, with their deep convective envelopes, efficiently dampen misaligned obliquities.

Keywords: M dwarf stars, Exoplanet migration, Exoplanets, Hot Jupiters, Radial velocity, Exoplanet formation
Increased Molecular Gas Velocity Dispersion and Star Formation Efficiency in Barred Galaxy Centres. Work by the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) collaboration found higher molecular gas surface densities and velocity dispersions in the centers of barred galaxies compared to unbarred galaxies. We explore central molecular gas using published high resolution (150 pc) measurements of CO(2─1) from the PHANGS-ALMA survey and a new velocity dispersion-dependent prescription for the CO-to-H2 conversion factor αCO. Comparisons of the molecular gas surface density, velocity dispersion, star formation rate, and depletion time reveal that these quantities are different in the centers of barred and unbarred galaxies. Gas depletion times are found to be shorter in barred galaxy centers. Even when we control for the presence of an active galactic nucleus, the velocity dispersion and depletion time are found to be statistically different between barred and unbarred galaxy centers. The higher velocity dispersion suggests extra noncircular motions, possibly due to the inflow of gas along the bar, that are not constant but must increase as the star formation rate increases.

Keywords: Molecular gas, Galaxy bars, Molecular clouds, Star formation, Interstellar medium, CO line emission, Barred spiral galaxies
Identification of Likely Methane Absorption Features in the Optical Spectra of Titan. The optical spectra of Titan reveal a rich set of absorption features, most of which are likely associated with methane (CH4). Methane is a key molecule in planetary and exoplanetary atmospheres, yet a comprehensive high-resolution linelist at optical wavelengths remains incomplete. This study identified and characterized potential CH4 absorption features in high-resolution optical spectra of Titan, providing essential data for linelist development and improving CH4 detection and characterization. We analyzed Titan spectra from the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) spectrograph (R ≍ 190,000), identifying intrinsic features and measuring their relative strengths. A conservative detection approach was employed, slightly overestimating solar and telluric contributions to distinguish them from Titan's intrinsic features. To assess the impact of spectral resolution, we compared the ESPRESSO data with Titan Ultraviolet and Visual Echelle Spectrograph (UVES) data (R ≍ 110,000). We identified 6195 absorption features in the ESPRESSO spectra potentially associated with CH4, of which 5436 are newly reported. ESPRESSO detected twice as many features as UVES in overlapping regions, highlighting the advantage of higher-resolution data. Most detected lines remained unresolved, so our reported features are primarily blended absorption structures. We estimated the detection limit for feature identification to correspond to a CH4 absorption coefficient of approximately 0.02 km am−1. Comparison of our results with a previous analysis of Titan UVES spectra and with experimental CH4 data at a similar temperature showed good agreement, while some discrepancies were observed when compared with data acquired at a different temperature. We provide a comprehensive list of Titan absorption features with key reliability metrics, along with Titan's intrinsic spectra, to support future studies.

Keywords: High resolution spectroscopy, Methane, Spectral line identification, Molecular spectroscopy, Titan, Planetary atmospheres, Habitable planets, Exoplanet atmospheres
NGTS-EB-8: A Double-lined Eclipsing M+M Binary Discovered by Citizen Scientists. We report the identification and characterization of a new binary system composed of two near-equal mass M-dwarfs. The binary NGTS-EB-8 was identified as a planet candidate in data from the Next Generation Transit Survey (NGTS) by citizen scientists participating in the Planet Hunters NGTS project. High-resolution spectroscopic observations reveal the system to be a double-lined binary. By modeling the photometric and radial velocity observations, we determine an orbital period of 4.2 days and the masses and radii of both stars to be  MA=0.250−0.004+0.005  M⊙,  MB=0.208−0.004+0.005  M⊙, and  RA=0.255−0.005+0.004  R⊙,  RB=0.233−0.005+0.006  R⊙, respectively. We detect Balmer line emission from at least one of the stars but no significant flare activity. We note that both components lie in the fully convective regime of low-mass stars (≲0.35 M⊙); therefore, they can be a valuable test for stellar evolutionary models. We demonstrate that the photometric observations, speckle imaging, and initial radial velocity measurements were unable to identify the true nature of this system and highlight that high-resolution spectroscopic observations are crucial in determining whether systems such as this are in fact binaries.

Keywords: Eclipsing binary stars, Transit photometry, M dwarf stars
Direct Measurement of Extinction in a Planet-hosting Gap. Recent disk observations have revealed multiple indirect signatures of forming gas giant planets, but high-contrast imaging has rarely confirmed the presence of the suspected perturbers. Here, we exploit a unique opportunity provided by the background star AS 209bkg, which shines through a wide annular gap in the AS 209 disk, to perform transmission spectrophotometry and directly measure the extinction from gap material for the first time. By combining new VLT/SPHERE and JWST/NIRCam observations with archival HST data from 2005, we model the spectral energy distribution (SED) of AS 209bkg over a 19 yr baseline. We find that the SED and its variability are best explained by increasing extinction along the line of sight as AS 209bkg approaches the gap edge in projection. The extinction is best described by the combination of an ISM-like extinction component and a grey extinction component. This points to the presence of grains in the disk outer gap that are larger than in the ISM. We find that the extinction in the gap at λ ∼ 4.0 μm is  A4μm=2.7−0.7+0.7  mag, while at Hα (λ = 0.656 μm), where most searches for accretion signatures take place, the extinction could be as high as  AHα=4.2−1.2+0.9  mag ( AV=4.6−1.3+1.0 ). This suggests that even wide, deep gaps can significantly obscure emission from protoplanets, even those following a hot-start evolutionary model. Our extinction measurements help reconcile the discrepancy between ALMA-based predictions of planet─disk interactions and the nondetections from sensitive optical and near-infrared imaging campaigns.

Keywords: Extinction, Coronagraphic imaging, Direct imaging, Protoplanetary disks, Exoplanet formation
THYME. XIII. Two Young Neptunes Orbiting a 75 Myr Star in the Alpha Persei Cluster. Young planets with mass measurements are particularly valuable in studying atmospheric mass-loss processes, but these planets are rare and their masses difficult to measure due to stellar activity. We report the discovery of a planetary system around TOI-6109, a young, 75 Myr-old Sun-like star in the Alpha Persei cluster. It hosts at least two transiting Neptune-like planets within 10 day orbital periods. Using three TESS sectors, 30 CHEOPS orbits, and photometric follow-up observations from the ground, we confirm the signals of the two planets. TOI-6109 b has an orbital period of P =  5.6904−0.0004+0.0004  days and a radius of R =  4.87−0.12+0.16  R⊕. The outer planet, TOI-6109 c has an orbital period of P =  8.5388−0.0005+0.0006  days and a radius of R =  4.83−0.06+0.07  R⊕. These planets orbit just outside a 3:2 mean motion resonance. The near-resonant configuration presents the opportunity to measure the planet's mass via TTV measurements and to bypass difficult RV measurements. Measuring the masses of the planets in this system will allow us to test theoretical models of atmospheric mass loss.

Keywords: Hot Neptunes, Transit photometry, Exoplanet detection methods
An Improved Upper Limit of Cyanodiacetylene (HC<SUB>5</SUB>N) in the Atmosphere of Titan. In the complex Titan atmospheric chemistry, photochemical reactions involving cyanodiacetylene (HC5N) may be important as reaction pathways that could lead to the production of amines and aromatic molecules. We carried out a new comprehensive search of HC5N in Titan's atmosphere using Band 6 (215─275 GHz or 1.1─1.4 mm in wavelength) spectroscopic archival data from the Atacama Large Millimeter/submillimeter Array. To search for a faint spectral line feature of HC5N, we used a spectral stacking method that integrates different transition data. Integrating six independent observation data sets with a total integration time of ∼15,000 s, we found no statistically significant detection of an HC5N spectral feature. Using the Planetary Spectrum Generator for radiative transfer modeling and employing the previously predicted vertical distribution proposed by V. Vuitton et al., E. Lellouch et al., J. C. Loison et al., and V. A. Krasnopolsky, we derived the upper limit column density of HC5N, corresponding to 3σ noise level, to be 0.3─10 × 1013 molecules cm─2 above ∼60 km altitude (depending on the assumed vertical profile). The corresponding upper limit of [HC5N]/[HC3N] ratio value derived from three of four models seem to be lower than that measured in high-mass protostellar objects, possibly due to the lower abundance of C4H2.

Keywords: Submillimeter astronomy, Planetary atmospheres
Gaia DR3 Open Cluster Cepheids: A Unified Catalog with Calibrated Period─Age and Period─Wesenheit Relations. Classical Cepheids (CCs) in Galactic open clusters (OCs) provide essential observational constraints for calibrating the period─age relation (PAR) and the period─Wesenheit relation (PWR) of CCs. However, distant and long-period OC Cepheids remain limited, while the confirmed samples still require more precise determinations of their physical properties, such as ages and extinctions. In this work, we present a comprehensive census of OC Cepheids based on an extensive sample of distant OCs from Gaia Data Release 3 (DR3). By combining astrometric and photometric membership analyses, we identified 110 CCs associated with 102 OCs, of which 41 CCs across 37 OCs were classified as OC Cepheids, while the remaining cases were considered candidate or rejected associations. Our results are consistent with previous studies, while 4 of the 41 OC Cepheids are newly reported here. Using updated cluster parameters derived from manual isochrone fitting, we primarily refined the PAR to  logAge  = (−0.595 ± 0.044)  logP  + (8.430 ± 0.042) and recalibrated the PWR to WG = (−3.615 ± 0.083)  logP  + (−2.379 ± 0.096). This study expands the sample of confirmed and candidate OC Cepheids. The newly longest-period confirmed OC Cepheid is BM Per (CWNU 3123) with  logP=1.36 , and two newly confirmed longest-period OC Cepheid candidates have distances exceeding 6 kpc. Moreover, the PAR and PWR are improved by incorporating refined OC ages and updated parallaxes, respectively.

Keywords: Open star clusters, Cepheid variable stars, Astronomy data analysis
Searching for Free-floating Planets with TESS: Results from Sectors 61─65. Though free-floating planets (FFPs) may outpopulate their bound counterparts in the terrestrial-mass range, they remain one of the least explored exoplanet demographics. Due to their negligible electromagnetic emission at all wavelengths, the only observational technique able to detect these worlds is gravitational microlensing. Microlensing by terrestrial-mass FFPs induces rare, short-duration magnifications of background stars, requiring high-cadence, wide-field surveys to detect these events. The Transiting Exoplanet Survey Satellite (TESS), though designed to detect close-bound exoplanets via transits, boasts a full-frame image cadence as short as 200 s and has monitored hundreds of millions of stars, providing a unique dataset in which to search for rare short-duration transients. We have performed a preliminary search for FFP microlensing in 7.5 million light curves from TESS Sectors 61─65. We find one short-duration event with a light-curve morphology consistent with expectations for a low-mass FFP, but in tension with the expected FFP abundance in this mass range. We consider possible false-positive interpretations of this event such as stellar flares, heartbeat binaries, and centrifugal breakout. We find that all interpretations pose some challenges, and we discuss the possibility that the event may constitute a first example of a new class of pernicious false positives that future space-based microlensing efforts will encounter. Our ongoing search through the TESS dataset will significantly support the upcoming hunt for rogue worlds with dedicated space-based microlensing surveys, and our results may be used alongside these surveys to place interesting constraints on the spatial distribution of FFPs in the Galaxy.

Keywords: Free floating planets, Gravitational microlensing exoplanet detection, Exoplanets
Eclipse Timing Variations of Circumbinary Substellar Objects in TESS Data. Circumbinary planets and brown dwarfs form in complex gravitational environments, offering insights into formation, orbital stability, and habitability prospects. However, they remain underrepresented, with only 60 confirmed or candidate systems known. In this work, we leverage TESS photometry to search for circumbinary companions through eclipse timing variations (ETVs), analyzing 152 detached eclipsing binaries. By modeling eclipse timings, we identify 37 systems with significant periodic signals, 19 of which have false-alarm probabilities below 0.01. One system, TIC 142979644, emerges as a promising candidate to host a circumbinary substellar companion, with estimated masses of 18.8MJ and 11.1MJ from different methods. Simulations using synthetic ETVs indicate a 5% recovery rate for circumbinary brown dwarfs and 0.1% for Jupiter-like planets, with median masses of  56.6MJ−23.4MJ+16.5MJ  and periods of  1404−953+1361  days. Our simulations show that the smallest detectable mass is 1.6MJ at a period of 1860 days and confirm that ETV methods are effective in detecting misaligned systems. In the absence of a detection, we set an upper limit of 40% on the occurrence rate of circumbinary brown dwarfs at the 2σ confidence level. In contrast, a confirmed single detection would imply an occurrence rate of 13.08%. These constraints are consistent with previous abundance estimates for circumbinary brown dwarfs (≲6.5%). As most circumbinary substellar companions detected through ETVs are found around post─common envelope binaries, our recovery rate of 0.83% in their progenitors implies that even a single detection would strongly favor a first-generation origin.

Keywords: Brown dwarfs, Exoplanets, Timing variation methods, Eclipsing binary stars, Exoplanet detection methods
Precise Constraints on the Energy Budget of WASP-121 b from Its JWST NIRISS/SOSS Phase Curve. Ultra-hot Jupiters exhibit day-to-night temperature contrasts upwards of 1000 K due to competing effects of strong winds, short radiative timescales, magnetic drag, and H2 dissociation/recombination. Spectroscopic phase curves provide critical insights into these processes by mapping temperature distributions and constraining the planet's energy budget across different pressure levels. Here, we present the first NIRISS/SOSS phase curve of an ultra-hot Jupiter, WASP-121 b. The instrument's bandpass [0.6─2.85 μm] captures an estimated 50%─83% of the planet's bolometric flux, depending on orbital phase, allowing for unprecedented constraints on the planet's global energy budget; previous measurements with HST/WFC3 and JWST/NIRSpec/G395H captured roughly 20% of the planetary flux. Accounting for the unobserved regions of the spectrum, we estimate effective day- and nightside temperatures of Tday = 2717 ± 17 K and  Tnight=1562−19+18  K corresponding to a Bond albedo of AB = 0.277 ± 0.016 and a heat recirculation efficiency of ϵ = 0.246 ± 0.014. Matching the phase-dependent effective temperature with energy balance models yields a similar Bond albedo of 0.3 and a mixed layer pressure of 1 bar consistent with photospheric pressures, but unexpectedly slow winds of 0.2 km s−1, indicative of inefficient heat redistribution. The shorter optical wavelengths of the NIRISS/SOSS Order 2 yield a geometric albedo of  Ag=0.093−0.027+0.029  (3σ upper limit of 0.175), reinforcing the unexplained trend of hot Jupiters exhibiting larger Bond than geometric albedos. We also detect near-zero phase curve offsets for wavelengths above 1.5 μm, consistent with inefficient heat transport, while shorter wavelengths potentially sensitive to reflected light show eastward offsets.

Keywords: Exoplanets, Exoplanet atmospheric dynamics, Planetary atmospheres, Exoplanet systems, Exoplanet astronomy, Exoplanet atmospheres, Exoplanet atmospheric structure