WASP-69 b is a hot, inflated, Saturn-mass planet 0.26 Mjup with a zero-albedo equilibrium temperature of 963 K. Here, we report the JWST 2 to 12 um emission spectrum of the planet consisting of two eclipses observed with NIRCam grism time series and one eclipse observed with MIRI LRS. The emission spectrum shows absorption features of water vapor, carbon dioxide and carbon monoxide, but no strong evidence for methane. WASP-69 b's emission spectrum is poorly fit by cloud-free homogeneous models. We find three possible model scenarios for the planet: 1) a Scattering Model that raises the brightness at short wavelengths with a free Geometric Albedo parameter 2) a Cloud Layer model that includes high altitude silicate aerosols to moderate long wavelength emission and 3) a Two-Region model that includes significant dayside inhomogeneity and cloud opacity with two different temperature-pressure profiles. In all cases, aerosols are needed to fit the spectrum of the planet. The Scattering model requires an unexpectedly high Geometric Albedo of 0.64. Our atmospheric retrievals indicate inefficient redistribution of heat and an inhomogeneous dayside distribution, which is tentatively supported by MIRI LRS broadband eclipse maps that show a central concentration of brightness. Our more plausible models (2 and 3) retrieve chemical abundances enriched in heavy elements relative to solar composition by 6x to 14x solar and a C/O ratio of 0.65 to 0.94, whereas the less plausible highly reflective scenario (1) retrieves a slightly lower metallicity and lower C/O ratio.

The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune 'desert' (a region in mass-radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b, which is thought to have an unusually massive core, and recent discoveries such as LTT9779b and NGTS-4b, on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune's but an anomalously large mass of $39.1^{+2.7}_{-2.6}$ Earth masses and a density of $5.2^{+0.7}_{-0.8}$ grams per cubic centimetre, similar to Earth's. Interior structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than $3.9^{+0.8}_{-0.9}$ per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation. Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.

Ultra-hot Jupiters (UHJs) are highly irradiated giant exoplanets with extremely high day-side temperatures, which lead to thermal dissociation of most of the molecular species. It is expected that the neutral hydrogen atom is one of the main species in the upper atmospheres of ultra-hot Jupiters. Neutral hydrogen has been detected in several UHJs by observing its Balmer line absorption. Here, we report four transit observations of the ultra-hot Jupiter WASP-33b, performed with the CARMENES and HARPS-North spectrographs, and the detection of the H${\alpha}$, H${\beta}$, and H${\gamma}$ lines in the planetary transmission spectrum. The combined H$\alpha$ transmission spectrum of the four transits has an absorption depth of 0.99$\pm$0.05 %, which corresponds to an effective radius of 1.31$\pm$0.01 Rp . The strong H${\alpha}$ absorption indicates that the line probes the high-altitude thermosphere. We further fitted the three Balmer lines using the PAWN model, assuming that the atmosphere is hydrodynamic and in LTE. We retrieved a thermosphere temperature $12200^{+1300}_{-1000}$ K and a mass-loss rate ${\rm \dot{M}}=10^{11.8^{+0.6}_{-0.5}}$ g/s. The retrieved large mass-loss rate is compatible with the "Balmer-driven" atmospheric escape scenario, in which the stellar Balmer continua radiation in the near-ultraviolet is substantially absorbed by the excited hydrogen atoms in the planetary thermosphere.

Anthropogenic skyglow dominates views of the natural night sky in most urban settings, and the associated emission of artificial light at night (ALAN) into the environment of cities involves a number of known and suspected negative externalities. One approach to lowering consumption of ALAN in cities is dimming or extinguishing publicly owned outdoor lighting during overnight hours; however, there are few reports in the literature about the efficacy of these programs. Here we report the results of one of the largest municipal lighting dimming experiments to date, involving $\sim$20,000 roadway luminaires owned and operated by the City of Tucson, Arizona, U.S. We analyzed both single-channel and spatially resolved ground-based measurements of broadband night sky radiance obtained during the tests, determining that the zenith sky brightness during the tests decreased by ($-5.4\pm0.9$)% near the city center and ($-3.6\pm0.9$)% at an adjacent suburban location on nights when the output of the street lighting system was dimmed from 90% of its full power draw to 30% after local midnight. Modeling these changes with a radiative transfer code yields results suggesting that street lights account for about ($14\pm1$)% of light emissions resulting in skyglow seen over the city. A separate derivation from first principles implies that street lighting contributes only 2-3% of light seen at the zenith over Tucson. We discuss this inconsistency and suggest routes for future work.

We present a new velocity-resolved survey of 2.9 $\mu$m spectra of hot H$_2$O and OH gas emission from protoplanetary disks, obtained with CRIRES at the VLT ($\Delta v \sim$ 3 km s$^{-1}$). With the addition of archival Spitzer-IRS spectra, this is the most comprehensive spectral dataset of water vapor emission from disks ever assembled. We provide line fluxes at 2.9-33 $\mu$m that probe from disk radii of $\sim0.05$ au out to the region across the water snow line. With a combined dataset for 55 disks, we find a new correlation between H$_2$O line fluxes and the radius of CO gas emission as measured in velocity-resolved 4.7 $\mu$m spectra (R$_{\rm co}$), which probes molecular gaps in inner disks. We find that H$_2$O emission disappears from 2.9 $\mu$m (hotter water) to 33 $\mu$m (colder water) as R$_{\rm co}$ increases and expands out to the snow line radius. These results suggest that the infrared water spectrum is a tracer of inside-out water depletion within the snow line. It also helps clarifying an unsolved discrepancy between water observations and models, by finding that disks around stars of M$_{\star}>1.5$ M$_\odot$ generally have inner gaps with depleted molecular gas content. We measure radial trends in H$_2$O, OH, and CO line fluxes that can be used as benchmarks for models to study the chemical composition and evolution of planet-forming disk regions at 0.05-20 au. We propose that JWST spectroscopy of molecular gas may be used as a probe of inner disk gas depletion, complementary to the larger gaps and holes detected by direct imaging and by ALMA.

Directly detecting thermal emission from young extrasolar planets allows measurement of their atmospheric composition and luminosity, which is influenced by their formation mechanism. Using the Gemini Planet Imager, we discovered a planet orbiting the \$sim$20 Myr-old star 51 Eridani at a projected separation of 13 astronomical units. Near-infrared observations show a spectrum with strong methane and water vapor absorption. Modeling of the spectra and photometry yields a luminosity of L/LS=1.6-4.0 x 10-6 and an effective temperature of 600-750 K. For this age and luminosity, "hot-start" formation models indicate a mass twice that of Jupiter. This planet also has a sufficiently low luminosity to be consistent with the "cold- start" core accretion process that may have formed Jupiter.

The influx of icy pebbles to the inner regions of protoplanetary disks constitutes a fundamental ingredient in most planet formation theories. The observational determination of the magnitude of this pebble flux and its dependence on disk substructure (disk gaps as pebble traps) would be a significant step forward. In this work we analyze a sample of 21 T Tauri disks (with ages $\approx 0.5{-}2\mathrm{~Myr}$) using JWST/MIRI spectra homogeneously reduced with the JDISCS pipeline and high-angular-resolution ALMA continuum data. We find that the 1500/6000 K water line flux ratio measured with JWST - a tracer of cold water vapor and pebble drift near the snowline - correlates with the radial location of the innermost dust gap in ALMA continuum observations (ranging from 8.7 to 69 au), confirming predictions from recent models that study connections between the inner and outer disk reservoirs. We develop a population synthesis exploration of pebble drift in gapped disks and find a good match to the observed trend for early and relatively effective gaps, while scenarios where pebble drift happens quickly, gaps are very leaky, or where gaps form late are disfavored on a population level. Inferred snowline pebble mass fluxes (ranging between $10^{-6}$ and $10^{-3}~M_\oplus/\mathrm{yr}$ depending on gap position) are comparable to fluxes used in pebble accretion studies and those proposed for the inner Solar System, while system-to-system variations suggest differences in the emerging planetary system architectures and water budgets.

Here, we present a simple solution to problems that have plagued (extra)"galactic" astronomers and cosmologists over the last century. We show that "galaxy" formation, dark matter, and the tension in the expansion of the universe can all be explained by the natural behaviors of an overwhelmingly large population of exoplanets throughout the universe. Some of these ideas have started to be proposed in the literature, and we commend these pioneers revolutionizing our understanding of astrophysics. Furthermore, we assert that, since planets are obviously the ubiquitous answer to every current question that can be posed by astronomers, planetary science must then be the basis for all science, and therefore that all current funding for science be reserved for (exo)planetary science - we happily welcome all astronomers and other scientists.

Atmospheres are not spatially homogeneous. This is particularly true for hot, tidally locked exoplanets with large day-to-night temperature variations, which can yield significant differences between the morning and evening terminators -- known as limb asymmetry. Current transit observations with the James Webb Space Telescope (JWST) are precise enough to disentangle the separate contributions of these morning and evening limbs to the overall transmission spectrum in certain circumstances. However, the signature of limb asymmetry in a transit light curve is highly degenerate with uncertainty in the planet's time of conjunction. This raises the question of how precisely transit times must be measured to enable accurate studies of limb asymmetry, in particular with JWST. Although this degeneracy has been discussed in the literature, a general description of it has not been presented. In this work, we show how this degeneracy results from apparent changes in the transit contact times when the planetary disk has asymmetric limb sizes. We derive a general formula relating the magnitude of limb asymmetry to the amount by which it would cause the apparent time of conjunction to vary, which can reach tens of seconds. Comparing our formula to simulated observations, we find that numerical fitting techniques add additional bias to the measured time, of generally less than a second, resulting from the occultation geometry. We also derive an analytical formula for this extra numerical bias. These formulae can be applied to planning new observations or interpreting literature measurements, and we show examples for commonly studied exoplanets.

The 3C 220.3 system is a rare case of a foreground narrow-line radio galaxy ("galaxy A," $z_A = 0.6850$) lensing a background submillimeter galaxy ($z_{{\rm SMG1}} = 2.221$). New spectra from MMT/Binospec confirm that the companion galaxy ("galaxy B") is part of the lensing system with $z_B = 0.6835$. New three-color HST data reveal a full Einstein ring and allow a more precise lens model. The new HST images also reveal extended emission around galaxy A, and the spectra show extended [OII] emission with irregular morphology and complex velocity structure. All indications are that the two lensing galaxies are a gravitationally interacting pair. Strong [OII] emission from both galaxies A and B suggests current star formation, which could be a consequence of the interaction. This would indicate a younger stellar population than previously assumed and imply smaller stellar masses for the same luminosity. The improved lens model and expanded spectral energy distributions have enabled better stellar-mass estimates for the foreground galaxies. The resulting dark matter fractions are ~0.8, higher than previously calculated. Deeper Chandra imaging shows extended X-ray emission but no evidence for a point X-ray source associated with either galaxy. The detection of X-rays from the radio lobes of 3C 220.3 allows an estimate of ~3 nT for the magnetic fields in the lobes, a factor of ~3 below the equipartition fields, as typical for radio galaxies.

Impacts are the most ubiquitous processes on planetary bodies in our solar system. During these impact events, shock waves can deposit enough energy to produce shock-induced darkening in the target material, resulting in an alteration of its spectral properties. This spectral alteration can lead to an ambiguous taxonomic classification of asteroids and an incorrect identification of meteorite analogs. In this study, we investigated the effects of shock darkening on the visible and near-infrared spectra of ordinary chondrites and members of the howardites, eucrites, and diogenites clan. A decrease in albedo and suppression of the absorption bands with increasing shock darkening was observed for all the samples. We found that adding $\gtrsim$50\% of shock-darkened material to an unaltered sample was enough to change the taxonomic classification of an ordinary chondrite from S-complex to C- or X-complex. A similar amount was sufficient to change the taxonomic classification of a eucrite from V-type to O-type, whereas a eucrite composed of 100\% shock-darkened material was classified as a Q-type. We discuss the limitations of using just albedo for taxonomic classification of asteroids, which has implications for future space-based infrared surveys. We also investigated if shock darkening is responsible for a bias against the discovery of near-Earth objects (NEOs) with H and L chondrite-like compositions, which could explain the abundance of LL chondrites among NEOs.

In the course of studying the 3C 220.3 lensing system, spectra were obtained with the Binospec instrument on the MMT for 511 additional objects in 3C 220.3's vicinity. These gave 146 good-quality galaxy redshifts and identified 126 Galactic stars. The galaxy redshift histogram shows a peak near 3C 220.3's redshift, but there is no evidence for or against a galaxy group within 2 Mpc of 3C 220.3 itself. The spectra revealed 12 AGN candidates including a likely $z\approx4.64$ broad-line QSO. Visible and near-infrared imaging with HST allowed morphological classifications of 14 galaxies. One system is a potential analog of the Milky Way-LMC system with stellar mass ratio $\sim$0.6.

The Atacama Large Millimeter/submillimeter Array (ALMA) large program AGE-PRO explores protoplanetary disk evolution by studying gas and dust across various ages. This work focuses on ten evolved disks in Upper Scorpius, observed in dust continuum emission, CO and its isotopologues, and N$_2$H$^+$ with ALMA Bands 6 and 7. Disk radii, from the radial location enclosing 68% of the flux, are comparable to those in the younger Lupus region for both gas and dust tracers. However, solid masses are about an order of magnitude below those in Lupus and Ophiuchus, while the dust spectral index suggests some level of dust evolution. These empirical findings align with a combination of radial drift, dust trapping, and grain growth into larger bodies. A moderate correlation between CO and continuum fluxes suggests a link between gas and dust content, through the increased scatter compared to younger regions, possibly due to age variations, gas-to-dust ratio differences, or CO depletion. Additionally, the correlation between C$^{18}$O and N$_2$H$^+$ fluxes observed in Lupus persists in Upper Sco, indicating a relatively stable CO gas abundance over the Class II stage of disk evolution. In conclusion, the AGE-PRO survey of Upper Scorpius disks reveals intriguing trends in disk evolution. The findings point towards potential gas evolution and the presence of dust traps in these older disks. Future high-resolution observations are needed to confirm these possibilities and further refine our understanding of disk evolution and planet formation in older environments.

The architecture of planetary systems depends on the evolution of the disks in which they form. In this work, we develop a population synthesis approach to interpret the AGE-PRO measurements of disk gas mass and size considering two scenarios: turbulence-driven evolution with photoevaporative winds and MHD disk-wind-driven evolution. A systematic method is proposed to constrain the distribution of disk parameters from the disk fractions, accretion rates, disk gas masses, and CO gas sizes. We find that turbulence-driven accretion with initially compact disks ($R_0 \simeq 5-20~$au), low mass-loss rates, and relatively long viscous timescales ($t_{\nu,0} \simeq 0.4-3~$Myr or $\alpha_{SS} \simeq 2-4 \times 10^{-4}$) can reproduce the disk fraction and gas sizes. However, the distribution of apparent disk lifetime defined as the $M_D/\dot{M}_*$ ratio is severely overestimated by turbulence-driven models. On the other hand, MHD wind-driven accretion can reproduce the bulk properties of the disk populations from Ophiuchus to Upper Sco assuming compact disks with an initial magnetization of about $\beta \simeq 10^5$ ($\alpha_{DW} \simeq 0.5-1 \times 10^{-3}$) and a magnetic field that declines with time. More studies are needed to confirm the low masses found by AGE-PRO, notably for compact disks that question turbulence-driven accretion. The constrained synthetic disk populations can now be used for realistic planet population models to interpret the properties of planetary systems on a statistical basis.

We report the discovery of CO$_2$ gas emission around HD 23514, an F5V star in the $\sim$150 Myr-old Pleiades cluster, hosting one of the rare giant-impact disks with unique mineralogy dominated by silica dust. We show that the dust feature remains stable over several decades, and that the sub-$\mu$m grains, which give rise to the $\sim$9 $\mu$m feature, are co-spatial with the hot CO$_2$ molecules within the sub-au vicinity of the star. Examining the Spitzer spectrum taken 15 years earlier, we show that the CO$_2$ emission was also present at 4.3 $\sigma$ significance. The existence of tiny silica grains and volatile gas requires special conditions to prevent the rapid loss caused by stellar radiation pressure and photodissociation. We explore several pathways explaining the observed properties and suggest that a past giant impact and/or stripping atmospheric event, involving large bodies with volatile content similar to the carbonaceous chondritic material, can simultaneously explain both the silica and volatile emission. Our discovery provides an important context for the amount of volatiles that a newly formed planet or the largest planetesimals could retain during the giant impact phase in the early solar system evolution.

The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years, gathering a rich and variable dataset. Amongst the data from the Rosetta Plasma Consortium (RPC) suite of instruments are measurements of the total electron density from the Mutual Impedance Probe (MIP) and Langmuir Probe (LAP). At low outgassing, the plasma density measurements can be explained by a simple balance between the production through ionisation and loss through transport. Ions are assumed to travel radially at the outflow speed of the neutral gas. Near perihelion, the assumptions of this field-free chemistry-free model are no longer valid, and plasma density is overestimated. This can be explained by enhanced ion transport by an ambipolar electric field inside the diamagnetic cavity, where the interplanetary magnetic field does not reach. In this study, we explore the transition between these two regimes, at intermediate outgassing ($5.4 \times10^{26}~\mathrm{s^{-1}}$), when the interaction between the cometary and solar wind plasma influences the transport of the ions. We use a 3D collisional test-particle model, adapted from Stephenson et al. 2022 to model the cometary ions with input electric and magnetic fields from a hybrid simulation for 2.5-3 au. The total plasma density from this model is then compared to data from MIP/LAP and to the field-free chemistry-free model. In doing so, we highlight the limitations of the hybrid approach and demonstrate the importance of modelling collisional cooling of the electrons to understand the ion dynamics close to the nucleus.

Transiting exoplanets in multi-planet systems exhibit non-Keplerian orbits as a result of the gravitational influence from companions which can cause the times and durations of transits to vary. The amplitude and periodicity of the transit time variations (TTV) are characteristic of the perturbing planet's mass and orbit. The objects of interest (TOI) from the Transiting Exoplanet Survey Satellite (TESS) are analyzed in a uniform way to search for TTVs with sectors 1-3 of data. Due to the volume of targets in the TESS candidate list, artificial intelligence is used to expedite the search for planets by vetting non-transit signals prior to characterizing the light curve time series. The residuals of fitting a linear orbit ephemeris are used to search for transit timing variations. The significance of a perturbing planet is assessed by comparing the Bayesian evidence between a linear and non-linear ephemeris, which is based on an N-body simulation. Nested sampling is used to derive posterior distributions for the N-body ephemeris and in order to expedite convergence custom priors are designed using machine learning. A dual input, multi-output convolutional neural network is designed to predict the parameters of a perturbing body given the known parameters and measured perturbation (O-C). There is evidence for 3 new multi-planet candidates (WASP-18, WASP-126, TOI-193) with non-transiting companions using the 2 minute cadence observations from TESS. This approach can be used to identify multi-planet systems and stars in need of longer radial velocity and photometric follow-up than those already performed.

With the aim of connecting the compositions of stars and planets, we present the abundances of carbon and oxygen, as well as iron and nickel, for the transiting exoplanet host star XO-2N and its wide-separation binary companion XO-2S. Stellar parameters are derived from high-resolution, high-signal-to-noise spectra, and the two stars are found to be similar in their Teff, log g, iron ([Fe/H]), nickel ([Ni/H]) abundances. Their carbon ([C/H]) and oxygen ([O/H]) abundances also overlap within errors, although XO-2N may be slightly more C-rich and O-rich than XO-2S. The C/O ratios of both stars (~0.60+/-0.20) may also be somewhat larger than solar (C/O~0.50). The XO-2 system has a transiting hot Jupiter orbiting one binary component but not the other, allowing us to probe the potential effects planet formation might have on the host star composition. Additionally, with multiple observations of its atmosphere the transiting exoplanet XO-2b lends itself to compositional analysis, which can be compared to the natal chemical environment established by our binary star elemental abundances. This work sets the stage for determining how similar/different exoplanet and host star compositions are, and the implications for planet formation, by discussing the C/O ratio measurements in the unique environment of a visual binary system with one star hosting a transiting hot Jupiter.

The requirements-driven OSIRIS-REx Camera Suite (OCAMS) acquires images essential to collecting a sample from the surface of Bennu. During proximity operations, these images document the presence of satellites and plumes, record spin state, enable an accurate digital terrain model of the shape of the asteroid and identify any surface hazards. They confirm the presence of sampleable regolith on the surface, observe the sampling event itself, and image the sample head in order to verify its readiness to be stowed. They document the history of Bennu as an example of early solar system material, as a microgravity body with a planetesimal size-scale, and as a carbonaceous object. OCAMS is fitted with three cameras. The MapCam records point-source color images on approach to the asteroid in order to connect ground-based point-source observations of Bennu to later higher-resolution surface spectral imaging. The SamCam documents the sample site before, during, and after it is disturbed by the sample mechanism. The PolyCam, using its focus mechanism, observes the sample site at sub-centimeter resolutions, revealing surface texture and morphology. While their imaging requirements divide naturally between the three cameras, they preserve a strong degree of functional overlap. OCAMS and the other spacecraft instruments allow the OSIRIS-REx mission to collect a sample from a microgravity body on the same visit during which it was first optically acquired from long range, a useful capability as humanity explores near-Earth, Main-Belt and Jupiter Trojan asteroids.

Secondary eclipse observations of ultra-hot Jupiters have found evidence that hydrogen is dissociated on their daysides. Additionally, full-phase light curve observations of ultra-hot Jupiters show a smaller day-night emitted flux contrast than that expected from previous theory. Recently, it was proposed by Bell & Cowan (2018) that the heat intake to dissociate hydrogen and heat release due to recombination of dissociated hydrogen can affect the atmospheric circulation of ultra-hot Jupiters. In this work, we add cooling/heating due to dissociation/recombination into the analytic theory of Komacek & Showman (2016) and Zhang & Showman (2017) for the dayside-nightside temperature contrasts of hot Jupiters. We find that at high values of incident stellar flux, the day-night temperature contrast of ultra-hot Jupiters may decrease with increasing incident stellar flux due to dissociation/recombination, the opposite of that expected without including the effects of dissociation/recombination. We propose that a combination of a greater number of full-phase light curve observations of ultra-hot Jupiters and future General Circulation Models that include the effects of dissociation/recombination could determine in detail how the atmospheric circulation of ultra-hot Jupiters differs from that of cooler planets.