High-contrast observations with JWST can reveal key composition and vertical mixing dependent absorption features in the spectra of directly imaged planets across the 3–5 μm wavelength range. We present novel coronagraphic images of the HR 8799 and 51 Eri planetary systems using the NIRCam Long Wavelength Bar in an offset "narrow" position. These observations have revealed the four known gas giant planets encircling HR 8799, even at spatial separations challenging for a 6.5 m telescope in the mid-infrared, including the first ever detection of HR 8799 e at 4.6 μm. The chosen filters constrain the strength of CO, CH₄, and CO₂ absorption in each planet's photosphere. The planets display a diversity of 3–5 μm colors that could be due to differences in composition and ultimately be used to trace their formation history. They also show stronger CO₂ absorption than expected from solar metallicity models, indicating that they are metal enriched. We detected 51 Eri b at 4.1 μm and not at longer wavelengths, which, given the planet's temperature, is indicative of out-of-equilibrium carbon chemistry and an enhanced metallicity. Updated orbits fit to the new measurement of 51 Eri b validate previous studies that find a preference for high eccentricities ($e=0.5{7}_{-0.09}^{+0.03}$), which likely indicates some dynamical processing in the system's past. These results present an exciting opportunity to model the atmospheres and formation histories of these planets in more detail in the near future, and are complementary to future higher-resolution, continuum-subtracted JWST spectroscopy.

Comparative studies of young and old exoplanet populations offer a glimpse into how planets may form and evolve with time. We present an occurrence rate study of short-period (<12 days) planets between 1.8 and 10 R_⊕ around 1374 FGK stars in nearby (200 pc) young clusters (<1 Gyr), utilizing data from the Transiting Exoplanet Survey Satellite mission. These planets represent a population closer to their primordial state. We find that the occurrence rate of young planets is higher ($6{4}_{-22}^{+32}$%) compared to the Gyr-old population observed by Kepler ($7.9{8}_{-0.35}^{+0.37}$%). Dividing our sample into bins of young (10–100 Myr) and intermediate (100 Myr–1 Gyr) ages, we also find that the occurrence distribution in orbital period remains unchanged, while the distribution in planet radius changes with time. Specifically, the radius distribution steepens with age, indicative of a larger planet population shrinking due to the atmospheric thermal cooling and mass loss. We also find evidence for an increase (1.9σ) in occurrence after 100 Myr, possibly due to tidal migration driving planets inside of 12 days. While evidence suggests that postdisk migration and atmospheric mass loss shape the population of short-period planets, more detections of young planets are needed to improve statistical comparisons with older planets. Detecting long-period young planets and planets <1.8 R_⊕ will help us understand these processes better. Additionally, studying young planetary atmospheres provides insights into planet formation and the efficiency of atmospheric mass-loss mechanisms on the evolution of planetary systems.

The planetary and lunar ephemerides called DE440 and DE441 have been generated by fitting numerically integrated orbits to ground-based and space-based observations. Compared to the previous general-purpose ephemerides DE430, seven years of new data have been added to compute DE440 and DE441, with improved dynamical models and data calibration. The orbit of Jupiter has improved substantially by fitting to the Juno radio range and Very Long Baseline Array (VLBA) data of the Juno spacecraft. The orbit of Saturn has been improved by radio range and VLBA data of the Cassini spacecraft, with improved estimation of the spacecraft orbit. The orbit of Pluto has been improved from use of stellar occultation data reduced against the Gaia star catalog. The ephemerides DE440 and DE441 are fit to the same data set, but DE441 assumes no damping between the lunar liquid core and the solid mantle, which avoids a divergence when integrated backward in time. Therefore, DE441 is less accurate than DE440 for the current century, but covers a much longer duration of years −13,200 to +17,191, compared to DE440 covering years 1550–2650.

Recent analyses have shown that distant orbits within the scattered disk population of the Kuiper Belt exhibit an unexpected clustering in their respective arguments of perihelion. While several hypotheses have been put forward to explain this alignment, to date, a theoretical model that can successfully account for the observations remains elusive. In this work we show that the orbits of distant Kuiper Belt objects (KBOs) cluster not only in argument of perihelion, but also in physical space. We demonstrate that the perihelion positions and orbital planes of the objects are tightly confined and that such a clustering has only a probability of 0.007% to be due to chance, thus requiring a dynamical origin. We find that the observed orbital alignment can be maintained by a distant eccentric planet with mass ≳10 m_⊕ whose orbit lies in approximately the same plane as those of the distant KBOs, but whose perihelion is 180° away from the perihelia of the minor bodies. In addition to accounting for the observed orbital alignment, the existence of such a planet naturally explains the presence of high-perihelion Sedna-like objects, as well as the known collection of high semimajor axis objects with inclinations between 60° and 150° whose origin was previously unclear. Continued analysis of both distant and highly inclined outer solar system objects provides the opportunity for testing our hypothesis as well as further constraining the orbital elements and mass of the distant planet.

We present 3 yr of high-contrast imaging of the PDS 70 b and c accreting protoplanets with the new extreme AO system MagAO-X as part of the MaxProtoPlanetS survey of Hα protoplanets. In 2023 and 2024, our sharp (25–27 mas FWHM), well-AO-corrected (20%–26% Strehl), deep (2–3.6 hr) images detected compact (r ∼ 30 mas; r ∼ 3 au) circumplanetary disks (CPDs) surrounding both protoplanets. Starlight scattering off the front edge of these dusty CPDs is the likely source of the bright compact continuum light detected within ∼30 mas of both planets in our simultaneously obtained continuum 668 nm filter images. After subtraction of contaminating continuum and point-spread function residuals with pyKLIP angular differential imaging and spectral differential imaging, we obtained high-contrast ASDI Hα images of both planets in 2022, 2023, and 2024. We find the Hα line flux of planet b fell by (8.1 ± 1.6) × 10⁻¹⁶ erg s⁻¹ cm⁻², a factor of 4.6 drop in flux from 2022 to 2023. In 2024 March, planet b continued to be faint with just a slight 1.6× rise to an Hα line flux of (3.64 ± 0.87) × 10⁻¹⁶ erg s⁻¹ cm⁻². For c, we measure a significant increase of (2.74 ± 0.51) × 10⁻¹⁶ erg s⁻¹ cm⁻² from 2023 to 2024, which is a factor of 2.3 increase. So both protoplanets have recently experienced significant Hα variability with ∼1 yr sampling. In 2024, planet c is brighter than b: as c is brightening and b generally fading. We also tentatively detect one new point source "CC3" inside the inner disk (∼49 mas; at PA ∼ 295°; 2024) with orbital motion roughly consistent with a ∼5.6 au orbit.

Located at the highest point on the Antarctic Plateau's ice sheet, Dome A is generally believed to be one of the best places on Earth for nighttime astronomy in the optical and near-infrared (NIR) bands. Daytime optical/NIR site characteristics are yet to be quantified, however. Here we report the first daytime observations of bright stars at the J band during the austral summer of 2023/2024. The experiments were conducted using a 150 mm telescope with a field of view of 0$\mathop{.}\limits^{\unicode{x000b0}}$87 × 0$\mathop{.}\limits^{\unicode{x000b0}}$69 and a pixel size of 2$\mathop{.}\limits^{\unicode{x02033}}$5. The sky brightness at zenith was measured to be ∼5.2 mag arcsec⁻² at noon when the solar elevation was  ∼27°, and it slightly darkened to  ∼5.8 mag arcsec⁻² at midnight with a solar elevation angle of  ∼10°. Stars as faint as J = 10.06 mag were significantly detected at 5σ levels with an effective exposure time of 175 s around midnight. The pathfinding experiments indicate that a sensitivity  ∼2 mag deeper can be reached by the planned 1 m class telescopes, taking advantage of the small free atmosphere seeing. Considering the high latitude and the extremely high fraction of clear days at this site, valuable bright transients with J ≲ 12 mag, such as (super)novae in the local universe and space debris at low orbits, within  ∼1/4 of the whole sky around the south celestial pole can be timely discovered and continuously monitored throughout the year.

The DESI Legacy Imaging Surveys (http://legacysurvey.org/) are a combination of three public projects (the Dark Energy Camera Legacy Survey, the Beijing–Arizona Sky Survey, and the Mayall z-band Legacy Survey) that will jointly image ≈14,000 deg² of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The combined survey footprint is split into two contiguous areas by the Galactic plane. The optical imaging is conducted using a unique strategy of dynamically adjusting the exposure times and pointing selection during observing that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering a catalog, constructed by using a probabilistic inference-based approach to estimate source shapes and brightnesses. The catalog includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12, and 22 μm) observed by the Wide-field Infrared Survey Explorer satellite during its full operational lifetime. The project plans two public data releases each year. All the software used to generate the catalogs is also released with the data. This paper provides an overview of the Legacy Surveys project.

The field of Search for Extraterrestrial Intelligence (SETI) searches for "technosignatures" could provide the first detection of life beyond Earth through the technology that an extraterrestrial intelligence may have created. Any given SETI survey, if no technosignatures are detected, should set upper limits based on the kinds of technosignatures it should have been able to detect; the sensitivity of many SETI searches requires that their target sources (e.g., Dyson spheres or Kardashev II/III level radio transmitters) emit with power far exceeding the kinds of technology humans have developed. In this paper, we instead turn our gaze Earthward, minimizing the axis of extrapolation by only considering transmission and detection methods commensurate with an Earth 2024 level. We evaluate the maximum distance of detectability for various present-day Earth technosignatures—radio transmissions, atmospheric technosignatures, optical and infrared signatures, and objects in space or on planetary surfaces—using only present-day Earth instruments, providing one of the first fully cross-wavelength comparisons of the growing toolbox of SETI techniques. In this framework, we find that Earth's space-detectable signatures span 13 orders of magnitude in detectability, with intermittent, celestially targeted radio transmission (i.e., planetary radar) beating out its nearest nonradio competitor by a factor of 10³ in detection distance. This work highlights the growing range of ways that exoplanet technosignatures may be expressed, the growing complexity and visibility of the human impact upon our planet, and the continued importance of the radio frequencies in SETI.

This paper presents VARnet, a capable signal-processing model for rapid astronomical time series analysis. VARnet leverages wavelet decomposition, a novel method of Fourier feature extraction via the finite-embedding Fourier transform, and deep learning to detect faint signals in light curves, utilizing the strengths of modern GPUs to achieve submillisecond single-source run time. We apply VARnet to the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) single-exposure database, which holds nearly 200 billion apparitions over 10.5 yr of infrared sources on the entire sky. This paper devises a pipeline in order to extract variable candidates from the NEOWISE data, serving as a proof of concept for both the efficacy of VARnet and methods for an upcoming variability survey over the entirety of the NEOWISE data set. We implement models and simulations to synthesize unique light curves to train VARnet. In this case, the model achieves an F1 score of 0.91 over a four-class classification scheme on a validation set of real variable sources present in the infrared. With ∼2000 points per light curve on a GPU with 22 GB of VRAM, VARnet produces a per-source processing time of <53 μs. We confirm that our VARnet is sensitive and precise to both known and previously undiscovered variable sources. These methods prove promising for a complete future survey of variability with the Wide-field Infrared Survey Explorer, and effectively showcase the power of the VARnet model architecture.

We present an analysis of adaptive optics images from the Keck I telescope of the microlensing event MOA-2011-BLG-262. The original discovery paper by Bennett et al. reports two possibilities for the lens system: a nearby gas giant lens with an exomoon companion or a very low-mass star with a planetary companion in the Galactic bulge. The ∼10 yr baseline between the microlensing event and the Keck follow-up observations allows us to detect the faint candidate lens host (star) at K = 22.3 mag and confirm the distant lens system interpretation. The combination of the host star brightness and light curve parameters yields host star and planet masses of M_host = 0.19 ± 0.03 M_⊙ and m_p = 28.92 ± 4.75 M_⊕ at a distance of D_L = 7.49 ± 0.91 kpc. We perform a multiepoch cross reference to Gaia Data Release 3 and measure a transverse velocity for the candidate lens system of v_L = 541.31 ± 65.75 km s⁻¹. We conclude this event consists of the highest-velocity exoplanet system detected to date, and also the lowest-mass microlensing host star with a confirmed mass measurement. The high-velocity nature of the lens system can be definitively confirmed with an additional epoch of high-resolution imaging at any time now. The methods outlined in this work demonstrate that the Roman Galactic Exoplanet Survey will be able to securely measure low-mass host stars in the bulge.

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: $0.10{0}_{-0.039}^{+0.036}$ (2.6σ) and $0.4{4}_{-0.12}^{+0.11}$ (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.

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 M_I = −4.05 mag for the TRGB stars, the modal absolute magnitude of the IAGB is then calculated to be M_I(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 M_I = −4.49  ± 0.003 mag in the LMC (4204 stars), M_I =  −4.67 ± 0.008 mag for the SMC (916 stars), and M_I =  −4.78 ± 0.030 mag for NGC 4258 (62 stars), leading to a global zero-point (weighted) average of  < M_I > =  −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.

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 ($68.{0}_{-2.2}^{+2.2}\,{M}_{{\rm{J}}}$) and TOI-5610b ($40.{4}_{-1.0}^{+1.0}\,{M}_{{\rm{J}}}$), two moderately massive brown dwarfs orbiting early M-dwarf hosts (T_eff = 3569 ± 59 K and 3618 ± 59 K, respectively). For TOI-5389Ab, the best fitting parameters are period P = 10.40046 ± 0.00002 days, radius ${R}_{{\rm{BD}}}=0.82{4}_{-0.031}^{+0.033}$R_J, and low eccentricity $e=0.096{2}_{-0.0046}^{+0.0027}$. 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 ${R}_{{\rm{BD}}}=0.88{7}_{-0.031}^{+0.031}$R_J, and moderate eccentricity $e=0.35{4}_{-0.012}^{+0.011}$. 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 < 13 days) exhibit a dearth of 13 M_J < M_BD < 40 M_J companions (q < 0.1) compared to those at slightly wider separations.

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.

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.

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: $0.10{0}_{-0.039}^{+0.036}$ (2.6σ) and $0.4{4}_{-0.12}^{+0.11}$ (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.

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 M_I = −4.05 mag for the TRGB stars, the modal absolute magnitude of the IAGB is then calculated to be M_I(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 M_I = −4.49  ± 0.003 mag in the LMC (4204 stars), M_I =  −4.67 ± 0.008 mag for the SMC (916 stars), and M_I =  −4.78 ± 0.030 mag for NGC 4258 (62 stars), leading to a global zero-point (weighted) average of  < M_I > =  −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.

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 ($68.{0}_{-2.2}^{+2.2}\,{M}_{{\rm{J}}}$) and TOI-5610b ($40.{4}_{-1.0}^{+1.0}\,{M}_{{\rm{J}}}$), two moderately massive brown dwarfs orbiting early M-dwarf hosts (T_eff = 3569 ± 59 K and 3618 ± 59 K, respectively). For TOI-5389Ab, the best fitting parameters are period P = 10.40046 ± 0.00002 days, radius ${R}_{{\rm{BD}}}=0.82{4}_{-0.031}^{+0.033}$R_J, and low eccentricity $e=0.096{2}_{-0.0046}^{+0.0027}$. 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 ${R}_{{\rm{BD}}}=0.88{7}_{-0.031}^{+0.031}$R_J, and moderate eccentricity $e=0.35{4}_{-0.012}^{+0.011}$. 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 < 13 days) exhibit a dearth of 13 M_J < M_BD < 40 M_J companions (q < 0.1) compared to those at slightly wider separations.

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.

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.

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.

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 $\bar{\gamma }=0.32\pm 0.04$ with a slight dependence on H (significantly smaller than Jupiter Trojans with $\bar{\gamma }=0.43\pm 0.02$). 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.

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 <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.

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.

While NGC 1514 is an elliptical, but complex, planetary nebula at optical wavelengths, it was discovered to have a pair of infrared-bright, axisymmetric rings contained within its faint outer shell during the course of the Wide-field Infrared Survey Explorer all-sky survey. We have obtained JWST mid-infrared imaging and spectroscopy of the nebula through the use of simultaneous observations with the MIRI Imager and Medium Resolution Spectrometer, selecting the F770W, F1280W, and F2550W filters to match each of the medium-resolution spectrometer's three grating positions. These observations show that the rings are clearly resolved and relatively distinct structures, with both filamentary and clumpy detail throughout. There is also cloud-like material that has a turbulent appearance in the interior of the rings, particularly at the longest wavelengths, and faint ejecta-like structures just outside the ring boundaries. Despite their brightness, the emission from the rings within the three imager passbands is shown to be dominated by thermal emission from very small grains, not line emission from atomic hydrogen or forbidden atomic lines, shocked molecular hydrogen, or polycyclic aromatic hydrocarbons. The Doppler velocities derived from the two brightest emission lines in the rings, however, suggest that the material from which the rings were formed was ejected during an early period of very heavy mass loss from the planetary nebula progenitor, then shaped by asymmetrical fast winds from the central binary pair.