Sazuna/UAT_keywords huggingface dataset:
The 10 pc Neighborhood of Habitable Zone Exoplanetary Systems: Threat Assessment from Stellar Encounters and Supernovae. The habitability of a planet is influenced by both its parent star and the properties of its local stellar neighborhood. Potential threats to habitability from the local stellar environment mainly arise from two factors: cataclysmic events such as powerful stellar explosions and orbital perturbations induced by close stellar encounters. Among the 4500+ exoplanet-hosting stars, about 140+ are known to host planets in their habitable zones (HZs). In this study, we use Gaia Data Release 3 data to investigate the 10 pc stellar neighborhood of the 84 habitable zone systems (HZSs) closest to the Sun. We assess the possible risks that the local stellar environments of these HZSs pose to their habitability. In particular, we find that HD 165155 has a high stellar density around it, making it likely to experience at least one flyby encounter within a span of 5 Gyr. We also identified two high-mass stars (M ≥ 8 M ⊙) as potential progenitors of supernovae, which could threaten the long-term survivability of HZSs HD 48265 and TOI-1227. Further, to quantify the similarity between HZ stars and the Sun, as well as their respective 10 pc stellar environments, we employ various astrophysical parameters to define a solar similarity index and a neighborhood similarity index. Our analysis suggests that HD 40307 exhibits the closest resemblance to the solar system, while HD 165155 shows the least resemblance.

Keywords: Solar neighborhood, Exoplanet astronomy, Close encounters, Habitable zone, Gaia, Habitable planets
Continuous Fragmentation of Comet 157P/Tritton. We observed the split comet 157P/Tritton in 2022 October–November and 2024 January with the Nordic Optical Telescope. Our observations show that the splitting continued during the entire observing campaign. Fragmentation was associated with outbursts, consistent with the action of outgassing torques that spun up the nucleus and its fragments to the point of rotational instability. The outburst-fragmentation events can lead to a runaway process where the increasing spin rate, driven by outgassing torques, results in repeated mass loss until the sublimating body completely disintegrates.

Keywords: Comets, Small Solar System bodies
JWST COMPASS: The First Near- to Mid-infrared Transmission Spectrum of the Hot Super-Earth L 168-9 b. We present the first broadband near- to mid-infrared (3─12 μm) transmission spectrum of the highly irradiated (T eq = 981 K) M-dwarf rocky planet L 168-9 b (TOI-134 b) observed with the Near-infrared Spectrograph and Mid-infrared Instrument (MIRI) instruments aboard JWST. We measure the near-infrared transit depths to a combined median precision of 20 ppm across the three visits in 54 spectroscopic channels with uniform widths of 60 pixels (∼0.2 μm wide; R ∼ 100), and the mid-infrared transit depths to 61 ppm median precision in 48 wavelength bins (∼0.15 μm wide; R ∼ 50). We compare the transmission spectrum of L 168-9 b to a grid of 1D thermochemical equilibrium forward models, and rule out atmospheric metallicities of less than 100× solar (mean molecular weights &lt;4 g mol−1) to 3σ confidence assuming high surface pressure (&gt;1 bar), cloudless atmospheres. Based on photoevaporation models for L 168-9 b with initial atmospheric mass fractions ranging from 2% to 100%, we find that this planet could not have retained a primordial H/He atmosphere beyond the first 200 Myr of its lifetime. Follow-up MIRI eclipse observations at 15 μm could make it possible to confidently identify a CO2-dominated atmosphere on this planet if one exists.

Keywords: Exoplanet atmospheric composition , Infrared spectroscopy, Exoplanet atmospheres, Exoplanets
On the Local Formation of the TRAPPIST-1 Exoplanets. The discovery of seven approximately Earth-mass planets orbiting the 0.09 M ⊙ M dwarf TRAPPIST-1 captivated the public and sparked a proliferation of investigations into the system's origins. Among other properties, the resonant architecture of the planets has been interpreted to imply that orbital migration played a dominant role in the system's early formation. If correct, this hypothesis could imply that all of the seven worlds formed far from the star, and might harbor enhanced inventories of volatile elements. However, multiple factors also contradict this interpretation. In particular, the planets' apparent rocky compositions and nonhierarchical mass distribution might be evidence that they formed closer to their current orbital locations. In this paper, we investigate the latter possibility with over 600 accretion simulations that model the effects of collisional fragmentation. In addition to producing multiple TRAPPIST-like configurations, we experiment with a number of different models for tracking the evolution of the planets' volatile contents and bulk iron-to-silicate ratios. We conclude that a trend in bulk iron contents is the more likely explanation for the observed radial trend of decreasing uncompressed densities in the real system. Given the degree of radial mixing that occurs in our simulations, in most cases we find that all seven planets finish with similar volatile contents. Another confounding quality of the TRAPPIST-1 system is the fact that the innermost planets are not in first-order resonances with one another. By applying a tidal migration model to our most promising accretion model results, we demonstrate cases where higher-order resonances are populated.

Keywords: Extrasolar rocky planets, M dwarf stars, Exoplanet astronomy, Exoplanet formation, Habitable planets, Planet formation
Searching for Planets Orbiting Vega with the James Webb Space Telescope. The most prominent of the IRAS debris disk systems, α Lyrae (Vega), at a distance of 7.7 pc, has been observed by both the NIRCam and MIRI instruments on the James Webb Space Telescope. This paper describes NIRCam coronagraphic observations, which have achieved F444W contrast levels of 3 × 10‑7 at 1″ (7.7 au), 1 × 10‑7 at 2″ (15 au), and a few × 10‑8 beyond 5″ (38 au), corresponding to masses of &lt;3, 2, and 0.5 M J for a system age of 700 Myr. Two F444W objects are identified in the outer MIRI debris disk, around 48 au. One of these is detected by MIRI and appears to be extended with a spectral energy distribution similar to those of distant extragalactic sources. The second one also appears extended in the NIRCam data suggestive of an extragalactic nature. The NIRCam limits within the inner disk (1″–10″) correspond to model-dependent masses of 2–3 M J. K. Y. L. Su et al. argue that planets larger than 0.3 M J would disrupt the smooth disk structure seen at MIRI wavelengths. Eight additional objects are found within 60″ of Vega, but none have astrometric properties or colors consistent with planet candidates. These observations reach a level consistent with expected Jeans mass limits. Deeper observations achieving contrast levels &lt; 10‑8 outside of ∼4″ and reaching masses below that of Saturn are possible, but may not reveal a large population of new objects.

Keywords: Coronagraphic imaging, Debris disks, Extrasolar gaseous giant planets, Exoplanets
CO Isotopologue-derived Molecular Gas Conditions and CO-to-H<SUB>2</SUB> Conversion Factors in M51. Over the past decade, several millimeter interferometer programs have mapped the nearby star-forming galaxy M51 at a spatial resolution of ≤170 pc. This study combines observations from three major programs: the PdBI Arcsecond Whirlpool Survey, the SMA M51 large program, and the Surveying the Whirlpool at Arcseconds with NOEMA. The data set includes the (1─0) and (2─1) rotational transitions of 12CO, 13CO, and C18O isotopologues. The observations cover the r &lt; 3 kpc region, including the center and part of the disk, thereby ensuring strong detections of the weaker 13CO and C18O lines. All observations are convolved in this analysis to an angular resolution of 4″, corresponding to a physical scale of 170 pc. We investigate empirical line ratio relations and quantitatively evaluate molecular gas conditions such as temperature, density, and the CO-to-H2 conversion factor (α CO). We employ two approaches to study the molecular gas conditions: (i) assuming local thermodynamic equilibrium (LTE) to analytically determine the CO column density and α CO, and (ii) using non-LTE modeling with RADEX to fit physical conditions to observed CO isotopologue intensities. We find that the α CO values in the center and along the inner spiral arm are ∼0.5 dex (LTE) and 0.1 dex (non-LTE) below the Milky Way inner disk value. The average non-LTE α CO is 2.4 ± 0.5 M ⊙ pc−2 (K km s−1)−1. While both methods show dispersion due to underlying assumptions, the scatter is larger for LTE-derived values. This study underscores the necessity for robust CO line modeling to accurately constrain the molecular interstellar medium's physical and chemical conditions in nearby galaxies.

Keywords: Radio spectroscopy, Spiral galaxies, Millimeter-wave spectroscopy, Giant molecular clouds, Radio interferometry
Orbital Migration Through Atmospheric Mass Loss. Atmospheric mass loss is thought to have strongly shaped the sample of close-in exoplanets. These atmospheres should be lost isotropically, leading to no net migration on the planetary orbit. However, strong stellar winds can funnel the escaping atmosphere into a tail trailing the planet. We derive a simple kinematic model of the gravitational interaction between the planet and this anisotropic wind, and derive expressions for the expected migration of the planet. Over the expected range of parameters, we find typical migrations of a few tenths to a few percent inward. We argue that this modest migration may be observable for planet pairs near mean motion resonances, which would provide an independent observational constraint on atmospheric mass loss models.

Keywords: Exoplanet migration
Sites of Planet Formation in Binary Systems. II. Double the Disks in DF Tau. This article presents the latest results of our Atacama Large Millimeter/submillimeter Array (ALMA) program to study circumstellar disk characteristics as a function of orbital and stellar properties in a sample of young binary star systems known to host at least one disk. Optical and infrared observations of the eccentric, ∼48 yr period binary DF Tau indicated the presence of only one disk around the brighter component. However, our 1.3 mm ALMA thermal continuum maps show two nearly equal-brightness components in this system. We present these observations within the context of updated stellar and orbital properties, which indicate that the inner disk of the secondary is absent. Because the two stars likely formed together, with the same composition, in the same environment, and at the same time, we expect their disks to be co-eval. However the absence of an inner disk around the secondary suggests uneven dissipation. We consider several processes that have the potential to accelerate inner disk evolution. Rapid inner disk dissipation has important implications for planet formation, particularly in the terrestrial-planet-forming region.

Keywords: Binary stars, Protoplanetary disks
Calibrating the Clock of JWST. JWST, despite not being designed to observe astrophysical phenomena that vary on rapid timescales, can be an unparalleled tool for such studies. If timing systematics can be controlled, JWST will be able to open up the subsecond infrared timescale regime. Rapid time-domain studies, such as lag measurements in accreting compact objects and solar system stellar occultations, require both precise interframe timing and knowing when a time series begins, down to an absolute accuracy significantly below 1 s. In this work, we present two long-duration observations of the deeply eclipsing double white dwarf system ZTF J153932.16+502738.8, which we use as a natural timing calibrator to measure the absolute timing accuracy of JWST's clock. From our two epochs, we measure an average clock accuracy of 0.12 ± 0.06 s, implying that JWST can be used for subsecond time-resolution studies down to the ∼100 ms level, a factor ∼5 improvement upon the prelaunch clock accuracy requirement. We also find an asymmetric eclipse profile in the F322W2 band, which we suggest has a physical origin.

Keywords: White dwarf stars, High time resolution astrophysics, Infrared astronomy, Time domain astronomy, Eclipsing binary stars
Significant Mutual Inclinations Between the Stellar Spin and the Orbits of Both Planets in the HAT-P-11 System. Planet─star obliquity and planet─planet mutual inclination encode a planetary system's dynamical history, but both of their values are hard to measure for misaligned systems with close-in companions. HAT-P-11 is a K4 star with two known planets: a close-in, misaligned super-Neptune with a ≍5 day orbit, and an outer super-Jupiter with a ≍10 yr orbit. In this work we present a joint orbit fit of the HAT-P-11 system with astrometry and S-index corrected radial velocity data. By combining our results with previous constraints on the orientation of the star and the inner planet, we find that all three angular momenta—those of the star, planet b, and planet c—are significantly misaligned. We confirm the status of planet c as a super-Jupiter, with 2.68 ± 0.41 M Jup at a semimajor axis of 4.10 ± 0.06 au, and planet b's mass of M  b sini b  = 0.074 ± 0.004 M Jup. We present the posterior probability distribution of obliquity between star A and planet c, and mutual inclination between planet b and planet c.

Keywords: Star-planet interactions, Radial velocity, Astrometric exoplanet detection
The HUSTLE Program: The UV to Near-infrared HST WFC3/UVIS G280 Transmission Spectrum of WASP-127b. Ultraviolet wavelengths offer unique insights into aerosols in exoplanetary atmospheres. However, only a handful of exoplanets have been observed in the ultraviolet to date. Here, we present the ultraviolet-visible transmission spectrum of the inflated hot Jupiter WASP-127b. We observed one transit of WASP-127b with WFC3/UVIS G280 as part of the Hubble Ultraviolet-optical Survey of Transiting Legacy Exoplanets, obtaining a transmission spectrum from 200 to 800 nm. Our reductions yielded a broadband transit depth precision of 91 ppm and a median precision of 240 ppm across 59 spectral channels. Our observations are suggestive of a high-altitude cloud layer with forward modeling showing they are composed of submicron particles and retrievals indicating a high-opacity patchy cloud. While our UVIS/G280 data only offer weak evidence for Na, adding archival Hubble Space Telescope (HST) WFC3/IR and STIS observations raises the overall Na detection significance to 4.1σ. Our work demonstrates the capabilities of HST WFC3/UVIS G280 observations to probe the aerosols and atmospheric composition of transiting hot Jupiters with comparable precision to HST STIS.

Keywords: Exoplanet atmospheres, Extrasolar gaseous giant planets, Exoplanets, Transmission spectroscopy
Deep Learning–based Measurement of Planetary Radial Velocities in the Presence of Stellar Variability. We present a deep learning–based approach for measuring small planetary radial velocities (RVs) in the presence of stellar variability. We use neural networks to reduce stellar RV jitter in 3 years of HARPS-N Sun-as-a-star spectra. We develop and compare dimensionality-reduction and data-splitting methods, as well as various neural network architectures including single-line convolutional neural networks (CNNs), an ensemble of single-line CNNs, and a multiline CNN. We inject planet-like RVs into the spectra and use the network to recover them. We find that the multiline CNN approach is able to recover 50 day period planets with 0.2 m s‑1 semiamplitude, with 8.8% error in the amplitude, compared to 80% error in the amplitude using a traditional cross-correlation function approach. This approach shows promise for mitigating stellar RV variability and enabling the detection of small planetary RVs with unprecedented precision.

Keywords: Radial velocity, Neural networks, Stellar activity
The Impact of Observing Cadence and Undetected Companions on the Accuracy of Planet Mass Measurements from Radial Velocity Monitoring. We conduct experiments on both real and synthetic radial velocity (RV) data to quantify the impact that observing cadence, the number of RV observations, and undetected companions all have on the accuracy of small planet mass measurements. We run resampling experiments on four systems with small transiting planets and substantial public data from the High Resolution Echelle Spectrometer in order to explore how degrading observing cadence and the number of RVs affects the planets' mass measurement relative to a baseline value. From these experiments, we recommend that observers obtain 2–3 RVs per orbit of the innermost planet and acquire at minimum 40 RVs. Following these guidelines, we then conduct simulations using synthetic RVs to explore the impact of undetected companions and untreated red noise on the masses of planets with known orbits. While undetected companions generally do not bias the masses of known planets, in some cases, when coupled with an inadequate observing baseline, they can cause the mass of an inner transiting planet to be systematically overestimated on average.

Keywords: Radial velocity, Exoplanets
HD 119130 b Is Not an "Ultradense" Sub-Neptune. We present a revised mass measurement for HD 119130 b (aka K2-292 b), a transiting planet (P = 17 days, R p =  2.63−0.10+0.11  R ⊕) orbiting a chromospherically inactive G dwarf, previously thought to be one of the densest sub-Neptunes known. Our follow-up Doppler observations with HARPS, HARPS-N, and HIRES reveal that HD 119130 b is, in fact, nearly one-third as massive as originally suggested by its initial confirmation paper. Our revised analysis finds M p = 8.8 ± 3.2 M ⊕ (M p &lt; 15.4 M ⊕ at 98% confidence) compared to the previously reported M p = 24.5 ± 4.4 M ⊕. While the true cause of the original mass measurement's inaccuracy remains uncertain, we present the plausible explanation that the planet's radial velocity (RV) semiamplitude was inflated due to constructive interference with a second, untreated sinusoidal signal in the data (possibly rotational modulation from the star). HD 119130 b illustrates the complexities of interpreting the RV orbits of small transiting planets. While RV mass measurements of such planets may be precise, they are not necessarily guaranteed to be accurate. This system serves as a cautionary tale as observers and theorists alike look to the exoplanet mass─radius diagram for insights into the physics of small-planet formation.

Keywords: Radial velocity, Exoplanets
Preparing for the Early eVolution Explorer: Characterizing the Photochemical Inputs and Transit Detection Efficiencies of Young Planets Using Multiwavelength Flare Observations by TESS and Swift. Ultraviolet flare emission can drive photochemistry in exoplanet atmospheres and even serve as the primary source of uncertainty in atmospheric retrievals. Additionally, flare energy budgets are not well understood due to a paucity of simultaneous observations. We present new near-UV (NUV) and optical observations of flares from three M dwarfs obtained at 20 s cadence with Swift and the Transiting Exoplanet Survey Satellite (TESS), along with a reanalysis of flares from two M dwarfs in order to explore the energy budget and timing of flares at NUV-optical wavelengths. We find a 9000 K blackbody underestimates the NUV flux by ≥2× for 54 ± 14% of flares and 14.8× for one flare. We report time lags between the bands of 0.5─6.6 minutes and develop a method to predict the qualitative flare shape and time lag to 36% ± 30% accuracy. The scatter present in optical-NUV relations is reduced by a factor of 2.0 ± 0.6 when comparing the total NUV energy with the TESS energy during the FWHM duration due to the exclusion of the Teff ≍ 5000 K tail. We show the NUV light curve can be used to remove flares from the optical light curve and consistently detect planets with 20% smaller transits than is possible without flare detrending. Finally, we demonstrate a 10× increase in the literature number of multiwavelength flares with the Early eVolution Explorer (EVE), an astrophysics Small Explorer concept to observe young clusters with simultaneous NUV and optical bands in order to detect young planets, assess their photochemical radiation environments, and observe accretion.

Keywords: Young star clusters, Stellar flares, Near ultraviolet astronomy, Exoplanet atmospheric evolution
Enhanced Stability in Planetary Systems with Similar Masses. This study employs numerical simulations to explore the relationship between the dynamical instability of planetary systems and the uniformity of planetary masses within the system, quantified by the Gini index. Our findings reveal a significant correlation between system stability and mass uniformity. Specifically, planetary systems with higher mass uniformity demonstrate increased stability, particularly when they are distant from first-order mean motion resonances. In general, for nonresonant planetary systems with a constant total mass, non-equal-mass systems are less stable than equal mass systems for a given spacing in units of mutual Hill radius. This instability may arise from the equipartition of the total random energy, which can lead to higher eccentricities in smaller planets, ultimately destabilizing the system. This work suggests that the observed mass uniformity within multiplanet systems detected by Kepler may result from a combination of survival bias and ongoing dynamical evolution processes.

Keywords: Exoplanet systems, Exoplanets
Quantifying the Contamination from nearby Stellar Companions in Gaia DR3 Photometry. Identifying and removing binary stars from stellar samples is a crucial but complicated task. Regardless of how carefully a sample is selected, some binaries will remain and complicate interpretation of results, especially via flux contamination of survey photometry. One such sample is the data from the Gaia spacecraft, which is collecting photometry and astrometry of more than 109 stars. To quantify the impact of binaries on Gaia photometry, we assembled a sample of known binary stars observed with adaptive optics and with accurately measured parameters, which we used to predict Gaia photometry for each stellar component. We compared the predicted photometry to the actual Gaia photometry for each system, and found that the contamination of Gaia photometry because of multiplicity decreases nonlinearly from near-complete contamination (ρ ≤  ) to no contamination (binary projected separation, or ρ &gt;  ). We provide an analytic relation to analytically correct photometric bias in a sample of Gaia stars using the binary separation. This correction is necessary because the Gaia PSF photometry extraction does not fully remove the secondary star flux for binaries with separations with ρ ≲  . We also evaluated the utility of various Gaia quality-of-fit metrics for identifying binary stars and found that Renormalized Unit Weight Error (RUWE) remains the best indicator for unresolved binaries, but multipeak image fraction probes a separation regime not currently accessible to RUWE.

Keywords: Surveys, Astronomical techniques, Binary stars