Sazuna/UAT_keywords huggingface dataset:
What if we Find Nothing? Bayesian Analysis of the Statistical Information of Null Results in Future Exoplanet Habitability and Biosignature Surveys. Future telescopes will survey temperate, terrestrial exoplanets to estimate the frequency of habitable (ηHab) or inhabited (ηLife) planets. This study aims to determine the minimum number of planets (N) required to draw statistically significant conclusions, particularly in the case of a null result (i.e., no detections). Using a Bayesian framework, we analyzed surveys of up to N = 100 planets to infer the frequency of a binary observable feature (ηobs) after null results. Posterior best fits and upper limits were derived for various survey sizes and compared with predicted yields from missions like the Large Interferometer for Exoplanets (LIFE) and the Habitable Worlds Observatory (HWO). Our findings indicate that N = 20–50 "perfect" observations (100% confidence in detecting or excluding the feature) yield conclusions relatively independent of priors. To achieve 99.9% upper limits of ηobs ≤ 0.2/0.1, approximately N ≃ 40/80 observations are needed. For "imperfect" observations, uncertainties in interpretation and sample biases become limiting factors. We show that LIFE and HWO aim for sufficiently large survey sizes to provide statistically meaningful estimates of habitable environments and life prevalence under these assumptions. However, robust conclusions require careful sample selection and high-confidence detection or exclusion of features in each observation.

Keywords: Surveys, Bayesian statistics, Exoplanets
Low 4.5 μm Dayside Emission Disfavors a Dark Bare-rock Scenario for the Hot Super-Earth TOI-431 b. The full range of conditions under which rocky planets can host atmospheres remains poorly understood, especially in the regime of close-in orbits around late-type stars. One way to assess the presence of atmospheres on rocky exoplanets is to measure their dayside emission as they are eclipsed by their host stars. Here, we present Spitzer observations of the 4.5 μm secondary eclipses of the rocky super-Earth TOI-431 b, whose mass and radius indicate an Earth-like bulk composition (3.07 ± 0.35 M⊕, 1.28 ± 0.04 R⊕). Exposed to more than 2000 times the irradiation of Earth, dayside temperatures of up to 2400 K are expected if the planet is a dark bare rock without a significant atmosphere. Intriguingly, despite the strong stellar insolation, we measure a secondary-eclipse depth of only 33 ± 22 ppm, which corresponds to a dayside brightness temperature of   K. This notably low eclipse depth disagrees with the dark bare-rock scenario at the 2.5σ level, and suggests either that the planet is surrounded by an atmosphere or that it is a bare rock with a highly reflective surface. In the atmosphere scenario, the low dayside emission implies the efficient redistribution of heat to the nightside, or by molecular absorption in the 4–5 μm bandpass. In the bare-rock scenario, a surface composition made of a high-albedo mineral species such as ultramafic rock can lead to reduced thermal emission consistent with low eclipse depth measurement. Follow-up spectroscopic observations with the James Webb Space Telescope hold the key to constraining the nature of the planet.

Keywords: Extrasolar rocky planets, Exoplanets, Super Earths, Planetary atmospheres, Exoplanet atmospheres
Evidence of a Disk Wind Origin for Fluorescent H<SUB>2</SUB> in Classical T Tauri Stars. We use far-ultraviolet spectra of 36 T Tauri stars, predominately from the Hubble Space Telescope (HST) ULLYSES program, to examine the kinematic properties of fluorescent H2 emission lines for evidence of disk outflows. Leveraging improvements to the HST Cosmic Origins Spectrograph wavelength solution, we coadd isolated lines within four fluorescent progressions ([v',J'] = [1,4], [1,7], [0,2], and [3,16]) to improve signal-to-noise ratio (S/N), and we fit each coadded line profile with one or two Gaussian components. Of the high-S/N line profiles (S/N ≥ 12 at the peak of the profile), over half are best fit with a combination of a broad and a narrow Gaussian component. For profiles of the [1,4] and [1,7] progressions, we find a systematic blueshift of a few kilometers per second between the broad and narrow centroid velocities and stellar radial velocities. For the [0,2] progression, we find centroid velocities consistently blueshifted with respect to stellar radial velocities on the order of −5 km s−1 for the single and narrow components, and −10 km s−1 for the broad components. Overall, the blueshifts observed in our sample suggest that the molecular gas traces an outflow from a disk wind in some sources, and not solely disk gas in Keplerian rotation. The low-velocity systematic blueshifts, as well as emitting radii as inferred from line FWHMs, observed in our sample are similar to those observed with optical [O I] surveys of T Tauri stars. We estimate H2 mass-loss rates of 10−9 to 10−11 M⊙ yr−1, but incomplete knowledge of wind parameters limits comparisons to global models.

Keywords: Stellar accretion disks, Protoplanetary disks, Classical T Tauri stars, Circumstellar gas
The Transmission Spectrum of the Potentially Rocky Planet L 98-59 c. We present observations of the 1.35 ± 0.07 Earth radius planet L 98-59 c, collected using Wide Field Camera 3 on the Hubble Space Telescope (HST). L 98-59 is a nearby (10.6 pc), bright (H = 7.4 mag) M3V star that harbors three small, transiting planets. As one of the closest known transiting multi-planet systems, L 98-59 offers one of the best opportunities to probe and compare the atmospheres of rocky planets that formed in the same stellar environment. We measured the transmission spectrum of L 98-59 c, and the extracted spectrum showed marginal evidence (2.1σ) for wavelength-dependent transit depth variations that could indicate the presence of an atmosphere. We forward-modeled possible atmospheric compositions of the planet based on the transmission spectrum. Although L 98-59 was previously thought to be a fairly quiet star, we have seen evidence for stellar activity, and therefore we assessed a scenario where the source of the signal originates with inhomogeneities on the stellar surface. We also see a correlation between transits of L 98-59 c and L 98-59 b collected 12.5 hr apart, which is suggestive (but at &lt;2σ confidence) of a contaminating component from the star impacting the exoplanet spectrum. While intriguing, our results are inconclusive and additional data are needed to verify any atmospheric signal. Fortunately, additional data have been collected from both the HST and James Webb Space Telescope. Should this result be confirmed with additional data, L 98-59 c would be the first planet smaller than 2 Earth radii with a detected atmosphere.

Keywords: M dwarf stars, Exoplanet atmospheric composition , Super Earths, Transmission spectroscopy
Orbital and Absolute Magnitude Distribution of Hilda Population. The Hilda population of asteroids is located in a large orbital zone of long-term stability associated with the Jupiter J3/2 mean-motion resonance. They are a sister population of the Jupiter Trojans, since both of them are likely made up of objects captured from the primordial Kuiper Belt early in the solar system history. Comparisons between the orbital and physical properties of the Hilda and Trojan populations thus represent a test of outer planet formation models. Here we use a decade of observations from the Catalina Sky Survey (G96 site) to determine the bias-corrected orbital and magnitude distributions of Hildas. We also identify collisional families and the background population by computing a new catalog of synthetic proper elements for Hildas. We model the cumulative magnitude distribution of the background population using a local power-law representation with slope γ(H), where H is the absolute magnitude. For the largest Hildas, we find γ ≃ 0.5 with large uncertainty due to the limited population. Beyond H ≃ 11, we find that γ transitions to a mean value   with a slight dependence on H (significantly smaller than Jupiter Trojans with  ). We find that members of identified collisional families represent more than 60% of the total population (both bias counts). The bias-corrected populations contain about the same number of Hildas within the families and the background for H ≤ 16, but this number may increase to 60% of families when their location in the orbital space is further improved in the future.

Keywords: Hilda group, Small Solar System bodies, Solar system astronomy
Toward High-precision Mass Measurements of Two Sub-Neptunes in the K2-266 Planetary System Through Transit Timing. Sub-Neptunes have been found to be one of the most common types of exoplanets, yet their physical parameters and properties are poorly determined and in need of further investigation. In order to improve the mass measurement and parameter determination of two sub-Neptunes, K2-266 d and K2-266 e, we present new transit observations obtained with CHaracterising ExOPlanets Satellite and Transiting Exoplanet Survey Satellite, increasing the baseline of transit data from a few epochs to 165 epochs for K2-266 d, and to 121 epochs for K2-266 e. Through a two-stage-fitting process, it is found that the masses of K2-266 d and K2-266 e are 6.01 ± 0.43 M⊕ and 7.70 ± 0.58 M⊕, respectively. With these updated values and one order of magnitude better precision, we confirm the planets to belong to the population of planets that has been determined to be volatile-rich. Finally, we present the results of dynamical simulations, showing that the system is stable, the orbits are not chaotic, and that these two planets are close to but not in 4:3 mean motion resonance.

Keywords: Exoplanet astronomy, Exoplanet systems, Exoplanets, Exoplanet dynamics
Photobombing for the Large Interferometer For Exoplanets (LIFE). A New Criterion for Target Confusion and Application to a Mid-infrared Rotating Nulling Interferometer. One of the primary objectives in modern astronomy is to discover and study planets with characteristics similar to Earth. This pursuit involves analyzing the spectra of exoplanets and searching for biosignatures. Contamination of spectra by nearby objects (e.g., other planets and moons in the same system) is a significant concern and must be addressed for future exo-Earth searching missions. The aim is to estimate, for habitable planets, the probability of spectral contamination by other planets within the same star system. This investigation focuses on the Large Interferometer For Exoplanets (LIFE). Since the Rayleigh criterion is inapplicable to interferometers such as those proposed for LIFE, we present new criteria based on the principle of parsimony that take into account two types of issues: contamination or blending of point sources and cancellation of point sources due to destructive interference. We define a new spatial resolution metric associated with contamination or cancellation that generalizes to a broader family of observing instruments. In the current baseline design, LIFE is an X-array architecture nulling interferometer. Our investigation reveals that its transmission map introduces the potential for two point sources to appear as one, even if they do not appear in close proximity. We find that LIFE has a spatial resolution comparable to that of a traditional telescope with a diameter of D = 600 m, observing at λ = 4 μm. Our survey of a star system population shows that, out of 73.4 expected habitable planets detected, 71.3 are not contaminated, on average.

Keywords: Exoplanets, Interferometers, Spectroscopy, Space telescopes, Habitable planets
Potential Subsurface Lava Tube Skylight on the Western Flank of Elysium Mons, Mars. The western flank of Elysium Mons, Mars, hosts a potential cave candidate (PCC) associated with a partially collapsed pit chain, previously identified in the Mars Cave Catalog. This study presents the first comprehensive investigation of the PCC, employing high-resolution imagery, thermal observations, topographic, geological, and mineralogical analyses to evaluate its structure and resource potential, and hypothesized to connect to a potential subsurface lava tube cave. High-resolution imagery from CTX and HiRISE on board the Mars Reconnaissance Orbiter (MRO), captured across varying solar angles, reveals an elliptical structure with constant shadowed regions and partial roof collapse, suggesting significant depth and consistency with a Potential Subsurface Lava Tube Skylight. Unlike the adjacent pit chain, which cools rapidly at night due to the lack of subsurface connectivity, the PCC retains heat and shows warmer appearance, indicating connectivity with the subsurface cave environment. Thermal observations from THEMIS on board Mars Odyssey confirm a pronounced night-time thermal anomaly, while topographic data from Mars Orbiter Laser Altimeter on board Mars Global Surveyor (MGS) provide detailed elevation profiles. Mineralogical analysis using Gamma-Ray Spectrometer data from Mars Odyssey identifies geochemical signatures indicative of the presence of olivine and pyroxene, iron oxides, feldspars, and potential volcanic glass. The PCC's unique morphological, thermal, and mineralogical characteristics, along with cave entrance identification and insights from the conceptual model, highlight a potential environment for astrobiological investigations. These findings, derived from integrated data sets across MRO, Mars Odyssey, and MGS, provide crucial insights into Martian subsurface processes, resource availability, future human/robotic missions, and the planet's potential to support life.

Keywords: Mars, Planetary surfaces, Planetary mineralogy, Planetary geology
Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs. Brown dwarfs bridge the gap between stars and planets, providing valuable insight into both planetary and stellar-formation mechanisms. Yet the census of transiting brown-dwarf companions, in particular around M-dwarf stars, remains incomplete. We report the discovery of two transiting brown dwarfs around low-mass hosts using a combination of space- and ground-based photometry along with near-infrared radial velocities. We characterize TOI-5389Ab ( ) and TOI-5610b ( ), two moderately massive brown dwarfs orbiting early M-dwarf hosts (Teff = 3569 ± 59 K and 3618 ± 59 K, respectively). For TOI-5389Ab, the best fitting parameters are period P = 10.40046 ± 0.00002 days, radius   RJ, and low eccentricity  . In particular, this constitutes one of the most extreme substellar-stellar companion-to-host mass ratios of q = 0.150. For TOI-5610b, the best-fitting parameters are period P = 7.95346 ± 0.00002 days, radius   RJ, and moderate eccentricity  . Both targets are expected to have shallow, but potentially observable, occultations: ≲500 ppm in the Johnson K band. A statistical analysis of M-dwarf/BD systems reveals for the first time that those at short orbital periods (P &lt; 13 days) exhibit a dearth of 13 MJ &lt; MBD &lt; 40 MJ companions (q &lt; 0.1) compared to those at slightly wider separations. *Based on observations obtained with the Hobby─Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximillians- Universitaet Muenchen, and Georg-August Universitaet Gottingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: Brown dwarfs, Transits, Substellar companion stars, Photometry, Spectroscopy, Transit photometry
I-band Asymptotic Giant Branch (IAGB) Stars. II. A First Estimate of Their Precision and a Differential Zero Point. Hubble Space Telescope observations of 92 galaxies that have a strong showing of I-band asymptotic giant branch (IAGB) stars in their color─magnitude diagrams (CMDs) are used to measure the relative offset between the mean apparent I-band magnitudes of the IAGB population and the corresponding apparent I-band magnitudes of the TRGB as measured in the same frames (and CMDs) of those individual galaxies. This first exploratory, large-sample comparison is independent of any extinction (foreground or internal) that may be shared by these two populations. The marginalized luminosity functions used to determine the modal value of the IAGB population are well fit by a single, symmetric Gaussian. The difference in the two apparent magnitudes (in the sense IAGB minus TRGB) is −0.589 mag, with a combined standard deviation of ±0.119 mag. Adopting MI = −4.05 mag for the TRGB stars, the modal absolute magnitude of the IAGB is then calculated to be MI(IAGB) = −4.64 ± 0.12 mag. The ensemble dispersion quoted above gives a standard error on the mean of ±0.012 mag (based on the full sample of 92 galaxies). Independently, the three geometry-based zero-points for I-band AGB stars are found (in Paper I) to be MI = −4.49 ± 0.003 mag in the LMC (4204 stars), MI = −4.67 ± 0.008 mag for the SMC (916 stars), and MI = −4.78 ± 0.030 mag for NGC 4258 (62 stars), leading to a global zero-point (weighted) average of &lt; MI &gt; = −4.64 ± 0.15 mag (stat). The scatter found in the anchors is comparable to the scatter in the field sample discussed here, but the calibration sample is small. The application of this method to galaxies well outside of the Local Group shows that these standard candles can readily be found and measured out to at least 9 Mpc, using already available archival data. *Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Keywords: Asymptotic giant branch stars, Carbon stars, Distance indicators
Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. V. Two Giant Planets in Kepler-511 but Only One Ran Away. Systems hosting multiple giant planets are important laboratories for understanding planetary formation and migration processes. We present a nearly decade-long Doppler spectroscopy campaign from the HIRES instrument on the Keck-I telescope to characterize the two transiting giant planets orbiting Kepler-511 on orbits of 27 days and 297 days. The radial velocity measurements yield precise masses for both planets:   (2.6σ) and   (4σ) Jupiter masses, respectively. We use these masses to infer their bulk metallicities (i.e., metal mass fraction 0.87 ± 0.03 and 0.22 ± 0.04, respectively). Strikingly, both planets contain approximately 25–30 Earth masses of heavy elements but have very different amounts of hydrogen and helium. Envelope mass loss cannot account for this difference due to the relatively large orbital distance and mass of the inner planet. We conclude that the outer planet underwent runaway gas accretion while the inner planet did not. This bifurcation in accretion histories is likely a result of the accretion of gas with very different metallicities by the two planets or the late formation of the inner planet from a merger of sub-Neptunes. Kepler-511 uniquely demonstrates how giant planet formation can produce dramatically different outcomes even for planets in the same system.

Keywords: Radial velocity, Exoplanet formation, Extrasolar gaseous giant planets, Transit photometry
JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 R<SUB>⊕</SUB> M Dwarf Planet. The atmospheres of planets between the size of Earth and Neptune at short orbital periods have been under intense scrutiny. Of the approximately dozen planets in this regime with atmospheres studied so far, a few appear to have prominent molecular features, while others appear relatively void of detectable atmospheres. Further work is therefore needed to understand the atmospheres of these planets, starting with observing a larger sample. To this end, we present the 3─5 μm transmission spectrum of TOI-776 c, a warm (Teq ∼ 420 K), ∼2 R⊕, ∼7 M⊕ planet orbiting an M1V star, measured with JWST NIRSpec/G395H. By combining two visits, we measure a median transit precision of ∼18 and ∼32 ppm in the NRS1 and NRS2 detectors, respectively. We compare the transmission spectrum to both nonphysical and physical models and find no strong evidence for molecular features. For cloud-top pressures larger than 10−3 bars, we rule out atmospheric metallicities less than 180─240× solar (depending on the reduction and modeling technique), which corresponds to a mean molecular weight of ∼6─8 g mol−1. However, we find that simple atmosphere mixture models (H2O + H2/He or CO2 + H2/He) give more pessimistic constraints, and we caution that mean molecular weight inferences are model dependent. We compare TOI-776 c to the similar planet TOI-270 d and discuss possible options for further constraining TOI-776 c's atmospheric composition. Overall, we suggest that these TOI-776 c observations may represent a combination of planetary and stellar parameters that fall just below the threshold of detectable features in small-planet spectra; finding this boundary is one of the main goals of the COMPASS program.

Keywords: James Webb Space Telescope, Exoplanet atmospheres
Extinction Distributions in Nearby Star-resolved Galaxies. I. M31. An extinction distribution of the Andromeda galaxy (M31) is constructed with member stars as tracers by fitting multiband photometric data from UKIRT/WFCAM, Panoramic Survey Telescope and Rapid Response System 1, and Gaia DR3. The resulting extinction distribution covers approximately 10 deg2 of M31 with a resolution of approximately 50″, providing the largest coverage to date based on stellar observations. The derived average extinction, AV = 1.17 mag, agrees well with previous studies. To account for foreground extinction, an extinction map of the Milky Way toward M31 with a resolution of ∼1 7 is also constructed, yielding an average extinction of AV ≈ 0.185 mag. The results offer a valuable tool for extinction correction in future observations, such as those from the China Space Station Telescope, and provide insights for improving dust models based on the spatial distribution of dust in galaxies like M31.

Keywords: Interstellar dust, Andromeda Galaxy, Interstellar extinction
Identification of Possible Stellar Companions via Speckle Interferometry in a Sample of Be Stars II. This study investigates the identification of possible stellar companions in a sample of Be stars using speckle interferometry. Be stars, which are rapidly rotating B-type stars exhibiting emission lines due to the presence of circumstellar disks, have been proposed to potentially reside in binary or multiple systems, which could influence their mass transfer processes and disk dynamics. We conducted observations of 46 Be stars using the 2.1 m telescope at the Observatorio Astronómico Nacional, Sierra San Pedro Mártir, Mexico, over two observing campaigns in 2018. With our observations, we identified secondary companions in 12 of the observed stars, five of which are new interferometric pairs. The angular separations of these newly identified pairs ranged from 0 09 to 0 33, with a maximum magnitude difference of Δm = 4.72 noted for star HD 41335. We estimated an observed multiplicity rate of ∼26% for our sample, thus reinforcing the existing knowledge of the multiplicity of Be stars. To further investigate the gravitational binding potential of the identified systems, we cross referenced our findings with data from Gaia Data Release 3. This analysis revealed that many potential companions, although not detected in our observations, were too faint (with G magnitudes ≥ 15.2) or too distant (separations greater than 2 0) to exert a significant influence on the circumstellar disk dynamics of the primary Be stars.

Keywords: Be stars, Interferometric binary stars, Visual binary stars, High angular resolution