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ABSTRACT We have developed an open-source pipeline for the analysis of Spitzer/IRAC channel 1 and 2 time-series photometry, incorporating some of the most popular decorrelation methods. We applied this pipeline to new phase curve observations of ultra-hot Jupiters MASCARA-1b and KELT-16b, and we performed the first comprehensive reanalysis of 15 phase curves. We find that MASCARA-1b and KELT-16b have phase offsets of $6^{+11}_{-11}~^{\circ }$W and $38^{+16}_{-15}~^{\circ }$W, dayside temperatures of $2952^{+100}_{-97}$  and $3070^{+160}_{-150}$ K, and nightside temperatures of $1300^{+340}_{-340}$ and $1900^{+430}_{-440}$ K, respectively. We confirm a strong correlation between dayside and irradiation temperatures with a shallower dependence for nightside temperature. We also find evidence that the normalized phase curve amplitude (peak-to-trough divided by eclipse depth) is correlated with stellar effective temperature. In addition, while our different models often retrieve similar parameters, significant differences occasionally arise between them, as well as between our preferred model and the literature values. Nevertheless, our preferred models are consistent with published phase offsets to within −8 ± 21 degrees (−1.6 ± 3.2 sigma), and normalized phase curve amplitudes are on average reproduced to within −0.01 ± 0.24 (−0.1 ± 1.6 sigma). Finally, we find that BLISS performs best in most cases, but not all; we therefore recommend future analyses consider numerous detector models to ensure an optimal fit and to assess model dependencies.

ABSTRACT We have developed an open-source pipeline for the analysis of Spitzer/IRAC channel 1 and 2 time-series photometry, incorporating some of the most popular decorrelation methods. We applied this pipeline to new phase curve observations of ultra-hot Jupiters MASCARA-1b and KELT-16b, and we performed the first comprehensive reanalysis of 15 phase curves. We find that MASCARA-1b and KELT-16b have phase offsets of $6^{+11}_{-11}~^{\circ }$W and $38^{+16}_{-15}~^{\circ }$W, dayside temperatures of $2952^{+100}_{-97}$  and $3070^{+160}_{-150}$ K, and nightside temperatures of $1300^{+340}_{-340}$ and $1900^{+430}_{-440}$ K, respectively. We confirm a strong correlation between dayside and irradiation temperatures with a shallower dependence for nightside temperature. We also find evidence that the normalized phase curve amplitude (peak-to-trough divided by eclipse depth) is correlated with stellar effective temperature. In addition, while our different models often retrieve similar parameters, significant differences occasionally arise between them, as well as between our preferred model and the literature values. Nevertheless, our preferred models are consistent with published phase offsets to within −8 ± 21 degrees (−1.6 ± 3.2 sigma), and normalized phase curve amplitudes are on average reproduced to within −0.01 ± 0.24 (−0.1 ± 1.6 sigma). Finally, we find that BLISS performs best in most cases, but not all; we therefore recommend future analyses consider numerous detector models to ensure an optimal fit and to assess model dependencies.

The JWST Early Release Observations (ERO) included a NIRISS/SOSS (0.6–2.8  μ m) transit of the ∼ 850 K Saturn-mass exoplanet HAT-P-18 b. Initial analysis of these data reported detections of water, escaping helium and haze. However, active K dwarfs like HAT-P-18 possess surface heterogeneities – star-spots and faculae – that can complicate the interpretation of transmission spectra, and indeed, a spot-crossing event is present in HAT-P-18 b's NIRISS/SOSS light curves. Here, we present an extensive reanalysis and interpretation of the JWST ERO transmission spectrum of HAT-P-18 b, as well as HST /WFC3 and Spitzer /IRAC transit observations. We detect H2O (12.5σ), CO2 (7.3σ), a cloud deck (7.4σ), and unocculted star-spots (5.8σ), alongside hints of Na (2.7σ). We do not detect the previously reported CH4 (log  CH4 < −6 to 2σ). We obtain excellent agreement between three independent retrieval codes, which find a sub-solar H2O abundance (log  H2O ≈ −4.4 ± 0.3). However, the inferred CO2 abundance (log  CO2 ≈ −4.8 ± 0.4) is significantly super-solar and requires further investigation into its origin. We also introduce new stellar heterogeneity considerations by fitting for the active regions' surface gravities – a proxy for the effects of magnetic pressure. Finally, we compare our JWST inferences to those from HST /WFC3 and Spitzer /IRAC. Our results highlight the exceptional promise of simultaneous planetary atmosphere and stellar heterogeneity constraints in the era of JWST and demonstrate that JWST transmission spectra may warrant more complex treatments of the transit light source effect. [ABSTRACT FROM AUTHOR]

The future is now – after its long-awaited launch in 2021 December, JWST began science operations in 2022 July and is already revolutionizing exoplanet astronomy. The Early Release Observations (ERO) programme was designed to provide the first images and spectra from JWST , covering a multitude of science cases and using multiple modes of each on-board instrument. Here, we present transmission spectroscopy observations of the hot-Saturn WASP-96 b with the Single Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph, observed as part of the ERO programme. As the SOSS mode presents some unique data reduction challenges, we provide an in-depth walk-through of the major steps necessary for the reduction of SOSS data: including background subtraction, correction of 1/ f noise, and treatment of the trace order overlap. We furthermore offer potential routes to correct for field star contamination, which can occur due to the SOSS mode's slitless nature. By comparing our extracted transmission spectrum with grids of atmosphere models, we find an atmosphere metallicity between 1× and 5× solar, and a solar carbon-to-oxygen ratio. Moreover, our models indicate that no grey cloud deck is required to fit WASP-96 b's transmission spectrum, but find evidence for a slope shortward of 0.9 μm, which could either be caused by enhanced Rayleigh scattering or the red wing of a pressure-broadened Na feature. Our work demonstrates the unique capabilities of the SOSS mode for exoplanet transmission spectroscopy and presents a step-by-step reduction guide for this new and exciting instrument. [ABSTRACT FROM AUTHOR]

Precise measurements of chemical abundances in planetary atmospheres are necessary to constrain the formation histories of exoplanets. A recent study of WASP-127 b, a close-in puffy sub-Saturn orbiting its solar-type host star in 4.2 d, using Hubble Space Telescope (HST) and Spitzer revealed a feature-rich transmission spectrum with strong excess absorption at 4.5 μm. However, the limited spectral resolution and coverage of these instruments could not distinguish between CO and/or CO2 absorption causing this signal, with both low and high C/O ratio scenarios being possible. Here we present near-infrared (0.9–2.5 μm) transit observations of WASP-127 b using the high-resolution SPIRou spectrograph, with the goal to disentangle CO from CO2 through the 2.3 μm CO band. With SPIRou, we detect H2O at a t -test significance of 5.3 σ and observe a tentative (3σ) signal consistent with OH absorption. From a joint SPIRou + HST + Spitzer retrieval analysis, we rule out a CO-rich scenario by placing an upper limit on the CO abundance of log10[CO] <−4.0, and estimate a log10[CO2] of −3.7 |$^{+0.8}_{-0.6}$| , which is the level needed to match the excess absorption seen at 4.5 μm. We also set abundance constraints on other major C-, O-, and N-bearing molecules, with our results favouring low C/O (0.10 |$^{+0.10}_{-0.06}$|), disequilibrium chemistry scenarios. We further discuss the implications of our results in the context of planet formation. Additional observations at high and low resolution will be needed to confirm these results and better our understanding of this unusual world. [ABSTRACT FROM AUTHOR]

Lava planets have non-global, condensible atmospheres similar to icy bodies within the Solar system. Because they depend on interior dynamics, studying the atmospheres of lava planets can lead to understanding unique geological processes driven by their extreme environment. Models of lava planet atmospheres have thus far focused on either radiative transfer or hydrodynamics. In this study, we couple the two processes by introducing ultraviolet (UV) and infrared (IR) radiation to a turbulent boundary layer model. We also test the effect of different vertical temperature profiles on atmospheric dynamics. Results from the model show that UV radiation affects the atmosphere much more than IR. UV heating and cooling work together to produce a horizontally isothermal atmosphere away from the substellar point regardless of the vertical temperature profile. We also find that stronger temperature inversions induce stronger winds and hence cool the atmosphere. Our simulated transmission spectra of the bound atmosphere show a strong SiO feature in the UV that would be challenging to observe in the planet's transit spectrum due to the precision required. Our simulated emission spectra are more promising, with significant SiO spectral features at 4.5 and 9 |$\mu$| m that can be observed with the James Webb Space Telescope. Different vertical temperature profiles produce discernible dayside emission spectra, but not in the way one would expect. [ABSTRACT FROM AUTHOR]

The field of exoplanet atmospheric characterization is trending towards comparative studies involving many planetary systems, and using Bayesian hierarchical modelling is a natural next step. Here we demonstrate two use cases. We first use hierarchical modelling to quantify variability in repeated observations by reanalysing a suite of 10 Spitzer secondary eclipse observations of the hot Jupiter XO-3 b. We compare three models: one where we fit 10 separate eclipse depths, one where we use a single eclipse depth for all 10 observations, and a hierarchical model. By comparing the widely applicable information criterion of each model, we show that the hierarchical model is preferred over the others. The hierarchical model yields less scatter across the suite of eclipse depths – and higher precision on the individual eclipse depths – than does fitting the observations separately. We find that the hierarchical eclipse depth uncertainty is larger than the uncertainties on the individual eclipse depths, which suggests either slight astrophysical variability or that single eclipse observations underestimate the true eclipse depth uncertainty. Finally, we fit a suite of published dayside brightness measurements for 37 planets using a hierarchical model of brightness temperature versus irradiation temperature. The hierarchical model gives tighter constraints on the individual brightness temperatures than the non-hierarchical model. Although we tested hierarchical modelling on Spitzer eclipse data of hot Jupiters, it is applicable to observations of smaller planets like hot Neptunes and super-Earths, as well as for photometric and spectroscopic transit or phase-curve observations. [ABSTRACT FROM AUTHOR]

ABSTRACT The influence of a galaxy's environment on its evolution has been studied and compared extensively in the literature, although differing techniques are often used to define environment. Most methods fall into two broad groups: those that use nearest neighbours to probe the underlying density field and those that use fixed apertures. The differences between the two inhibit a clean comparison between analyses and leave open the possibility that, even with the same data, different properties are actually being measured. In this work, we apply 20 published environment definitions to a common mock galaxy catalogue constrained to look like the local Universe. We find that nearest-neighbour-based measures best probe the internal densities of high-mass haloes, while at low masses the interhalo separation dominates and acts to smooth out local density variations. The resulting correlation also shows that nearest-neighbour galaxy environment is largely independent of dark matter halo mass. Conversely, aperture-based methods that probe superhalo scales accurately identify high-density regions corresponding to high-mass haloes. Both methods show how galaxies in dense environments tend to be redder, with the exception of the largest apertures, but these are the strongest at recovering the background dark matter environment. We also warn against using photometric redshifts to define environment in all but the densest regions. When considering environment, there are two regimes: the 'local environment' internal to a halo best measured with nearest neighbour and 'large-scale environment' external to a halo best measured with apertures. This leads to the conclusion that there is no universal environment measure and the most suitable method depends on the scale being probed. [ABSTRACT FROM AUTHOR]