![Joining of the inner and outer subsystems. The evolution of the semi-major axes is shown with continuous coloured lines for all planets, which are also labelled by circles whose size reflect the observed size of the planets. In our favoured scenario, planet e followed the inner edge while planets b, c and d were in the inner cavity. Planets f, g and h join the system later, undergoing inward disc-driven migration (the disc is depicted by the top shaded area, with the lighter shading on the right indicating that the disc will eventually disperse). Since planet g is more massive than f and h, it is likely to capture f in resonance (the 4:3 being the favoured commensurability [5]) and the two planets migrate in together. When f reaches the 3:2 resonance with e, the combined push from g-f is sufficient to dislodge planet e from the inner edge (shown as a blue line enclosing the top shaded area). Driven by a full OLT, the orbit of planet e decays faster than f and g, approaching the 3:2 resonance with d. Planet h is the last one to migrate in and capture g in the 3:2 resonance to complete the chain. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/08/Forming-the-Trappist-1-system.png?resize=1200%2C720&ssl=1)
Trappist-1 hosts 7 planets where period ratios of neighbouring pairs are close to the 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2 ratios in increasing distance from the star. The Laplace […]
TRAPPIST-1d
Posted inAstrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report, TRAPPIST-1
The Implications of Thermal Hydrodynamic Atmospheric Escape on the TRAPPIST-1 Planets
JWST observations of the 7-planet TRAPPIST-1 system will provide an excellent opportunity to test outcomes of stellar-driven evolution of terrestrial planetary atmospheres, including atmospheric escape, ocean loss and abiotic oxygen […]
Posted inAtmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, TRAPPIST-1
Do Temperate Rocky Planets Around M Dwarfs have an Atmosphere?
Detecting an atmosphere on nearby temperate planets is one of the most important scientific objectives of the Webb mission, an endeavour in practice limited to a handful of well-characterized planets: […]
Posted inAstrochemistry, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Status Report, TRAPPIST-1, Water/Hycean Worlds & Oceanography
Water Condensation Zones Around Main Sequence Stars
Understanding the set of conditions that allow rocky planets to have liquid water on their surface — in the form of lakes, seas or oceans — is a major scientific […]
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report
New Models of Reflection Spectra for Terrestrial Exoplanets: Present and Prebiotic Earth Orbiting Around Stars of Different Spectral Types
In order to recognize a habitable exoplanet from future observed spectra, we present new model reflected spectra and geometric albedo for modern and prebiotic (3.9 Ga) Earth-like exoplanets orbiting within […]