hot Jupiters Archives - Astrobiology

Model spectra (top) and Kp-voffset maps for the combination of all nights (bottom) of H2O, H2S, and CH4 for KELT-11 b. The grey shaded areas show the wavelength regions of the spectral orders used for the analysis. The dotted lines indicate the expected location of the planetary signal. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report

Upper Limits On Atmospheric Abundances Of KELT-11b And WASP-69b From A Retrieval Approach

by Keith CowingNovember 11, 2025November 11, 2025

WASP-69b and KELT-11b are two low-density hot Jupiters, which are expected to show strong atmospheric features in their transmission spectra.

Calculated dayside composition for HD 209458b. Dotted lines correspond to the initial composition (chemical equilibrium for the gas giants and equal uniform abundances for secondary atmospheres), dashed lines to a calculation where the initial temperature does not further evolve (only for the gas giants), and solid lines to a self-consistent calculation where temperature and chemical composition evolve together. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Status Report

The Mutual Influence of Disequilibrium Composition and Temperature in Exoplanet Atmospheres

by Keith CowingJune 19, 2025September 18, 2025

We have developed a 1D planetary atmosphere model that solves in a self-consistent manner the evolution of temperature and disequilibrium chemistry in the vertical direction.

Retrievals of Cassini/VIMS occultation of Titan. Top left: observations and best-fit TauREx retrievals. Bottom left: breakdown of the extinction contributions in the tholin + CH4(l)(HITRAN) case. Right: Atmospheric properties inferred for the tholin + CH4(l) (HITRAN) case. The source for the opacity data (i.e, HITRAN or ExoMol) is important and can slightly change the best-fit spectrum and retrieval interpretation. Overall, the Cassini data is dominated by molecular absorption from CH4, CO, C2H6, C3H8 and extinction by hydrocarbon aerosols (tholins + CHCH4(l). The shape of the 3.4 µm absorption feature is likely best explained by the contribution of multiple species including some contribution from tholins. Overall, retrieval interpretations of Titan’s atmosphere are compatible with stratospheric inferences from previous works (see Figure B1). -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Titan

Cloud and Haze Parameterization in Atmospheric Retrievals: Insights from Titan’s Cassini Data and JWST Observations of Hot Jupiters

by Keith CowingMay 27, 2025May 27, 2025

Context: Before JWST, telescope observations were not sensitive enough to constrain the nature of clouds in exo-atmospheres. Recent observations, however, have inferred cloud signatures as well as haze-enhanced scattering slopes […]

The mass-metallicity correlation among planets, with the x-axis representing planet mass in Jupiter masses (MJ ) and the y-axis denoting normalized planetary abundance, both are in logarithmic scales. Our normalized H2O abundances are denoted by blue open circles, while the solid blue line represents the best-fit linear regression. The shaded blue region delineates the 1σ and 2σ quantiles. The trend depicted in W19 is shown by the dotted blue line, which exhibits a slightly more significant slope than ours. The linear model in our analysis is expressed as log(H2O) = -0.92+0.32 −0.33log(M/MJ ) – 0.90+0.21 −0.20. A recent detection of H2O from JWST/NIRISS for HAT-P-18b (Fu et al. 2022) is shown in the light purple circle in Figure 2. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Exoplanets, -moons, -comets, Status Report

A Revisit Of The Mass-Metallicity Trends In Transiting Exoplanets

by Keith CowingFebruary 14, 2024

The two prevailing planet formation scenarios, core-accretion and disk instability, predict distinct planetary mass-metallicity relations. Yet, the detection of this trend remains challenging due to inadequate data on planet atmosphere […]

Maps of the wavelength dependent optical depth (on a log scale), with optical depths of 0.1, 1.0 and 10 indicated by dotted/solid/dashed line respectively. We compare the optical depth profiles for an R=10 km, ρ =2 g cm−3 , JWST Ice ver. A cometary composition impact at three different points in time, 1 year (A), 5 years (C), and 25 years (C - steady-state) after impact, with our unperturbed HD209458b reference model (D). To emphasise how the opacity of the atmosphere varies time we also include, on our steady-state opacity map, the 1 year (green), 5 year (blue), 25 year (red) and reference (orange) τ = 1 surfaces as light shading. Note the significant effect that the addition of cometary material has had on the optical depth, in particular how an optical depth of one is reached at lower pressures, averaging ∼ 10−2 bar at steady-state vs ∼ 10−1 bar in the unperturbed model, helping to explain the difference in the transmission spectra seen in Figure 8. -- astro-ph.EP

Comets and Asteroids, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Impact events, Jupiter, Status Report

The Impact Of Cometary Impacts On The Chemistry, Climate, And Spectra Of Hot Jupiter Atmospheres

by Keith CowingFebruary 9, 2024February 9, 2024

Impacts from icy and rocky bodies have helped shape the composition of solar system objects, for example the Earth-Moon system, or the recent impact of comet Shoemaker-Levy 9 with Jupiter. […]