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Abstract High-eccentricity gas giant planets serve as unique laboratories for studying the thermal and chemical properties of H/He-dominated atmospheres. One of the most extreme cases is HD 80606 b—a hot Jupiter orbiting a Sun-like star with an eccentricity of 0.93—which experiences an increase in incident flux of nearly 3 orders of magnitude as the star–planet separation decreases from 0.88 au at apoastron to 0.03 au at periastron. We observed the planet’s periastron passage using JWST’s NIRSpec/G395H instrument (2.8–5.2μm) during a 21 hr window centered on the eclipse. We find that, as the planet passes through periastron, its emission spectrum transitions from a featureless blackbody to one in which CO, CH₄, and H₂O absorption features are visible. We detect CH₄during postperiapse phases at 4.1–10.7σdepending on the phase and on whether a flux offset is included to account for NRS1 detector systematics. Following periapse, H₂O and CO are also detected at 4.2–5.5σand 3.7–4.4σ, respectively. Furthermore, we rule out the presence of a strong temperature inversion near the IR photosphere based on the lack of obvious emission features throughout the observing window. General circulation models had predicted an inversion during periapse passage. Our study demonstrates the feasibility of studying hot Jupiter atmospheres using partial phase curves obtained with NIRSpec/G395H. 

Abstract The launch of JWST has ushered in a new era of high-precision infrared astronomy, allowing us to probe nearby white dwarfs for cold dust, exoplanets, and tidally heated exomoons. While previous searches for these exoplanets have successfully ruled out companions as small as 7–10 Jupiter masses (M_Jup), no instrument prior to JWST has been sensitive to the likely more common sub-Jovian-mass planets around white dwarfs. In this paper, we present the first multiband photometry (F560W, F770W, F1500W, F2100W) taken of WD 2149+021 with the Mid-Infrared Instrument on JWST. After a careful search for both resolved and unresolved planets, we do not identify any compelling candidates around WD 2149+021. Our analysis indicates that we are sensitive to companions as small as ∼0.5M_Jupoutwards of 1.″263 (28.3 au) and ∼1.0M_Jupat the innermost working angle (0.″654, 14.7 au) at 3 Gyr with 5σconfidence, placing significant constraints on any undetected companions around this white dwarf. The results of these observations emphasize the exciting future of sub-Jovian planet detection limits by JWST, which can begin to constrain how often these planets survive their host stars' evolution. 

Abstract We report the discovery of two directly imaged, giant planet candidates orbiting the metal-rich, hydrogen atmosphere white dwarfs WD 1202−232 and WD 2105−82. JWST’s Mid-Infrared Instrument (MIRI) data on these two stars show a nearby resolved source at a projected separation of 11.47 and 34.62 au, respectively. Assuming the planets formed at the same time as their host stars, with total ages of 5.3 and 1.6 Gyr, the MIRI photometry is consistent with giant planets with masses ≈1–7M_Jup. The probability of both candidates being false positives due to red background sources is approximately 1 in 3000. If confirmed, these would be the first directly imaged planets that are similar in both age and separation to the giant planets in our own solar system, and they would demonstrate that widely separated giant planets like Jupiter survive stellar evolution. Giant planet perturbers are widely used to explain the tidal disruption of asteroids around metal-polluted white dwarfs. Confirmation of these two planet candidates with future MIRI imaging would provide evidence that directly links giant planets to metal pollution in white dwarf stars. 

Abstract The James Webb Space Telescope will be able to probe the atmospheres and surface properties of hot, terrestrial planets via emission spectroscopy. We identify 18 potentially terrestrial planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS) that would make ideal targets for these observations. These planet candidates cover a broad range of planet radii ( R p ∼ 0.6–2.0 R ⊕ ) and orbit stars of various magnitudes ( K s = 5.78–10.78, V = 8.4–15.69) and effective temperatures ( T eff ∼ 3000–6000 K). We use ground-based observations collected through the TESS Follow-up Observing Program (TFOP) and two vetting tools— DAVE and TRICERATOPS —to assess the reliabilities of these candidates as planets. We validate 13 planets: TOI-206 b, TOI-500 b, TOI-544 b, TOI-833 b, TOI-1075 b, TOI-1411 b, TOI-1442 b, TOI-1693 b, TOI-1860 b, TOI-2260 b, TOI-2411 b, TOI-2427 b, and TOI-2445 b. Seven of these planets (TOI-206 b, TOI-500 b, TOI-1075 b, TOI-1442 b, TOI-2260 b, TOI-2411 b, and TOI-2445 b) are ultra-short-period planets. TOI-1860 is the youngest (133 ± 26 Myr) solar twin with a known planet to date. TOI-2260 is a young (321 ± 96 Myr) G dwarf that is among the most metal-rich ([Fe/H] = 0.22 ± 0.06 dex) stars to host an ultra-short-period planet. With an estimated equilibrium temperature of ∼2600 K, TOI-2260 b is also the fourth hottest known planet with R p < 2 R ⊕ . 

Abstract We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define η ⊕ as the HZ occurrence of planets with radii between 0.5 and 1.5 R ⊕ orbiting stars with effective temperatures between 4800 and 6300 K. We find that η ⊕ for the conservative HZ is between (errors reflect 68% credible intervals) and planets per star, while the optimistic HZ occurrence is between and planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ∼6 pc away and there are ∼4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun.