TOI-2431 b
TOI-2431 b: a tiny, lava-hot world
TOI-2431 b is an ultra-close, rocky exoplanet that orbits the orange-dwarf star TOI-2431, about 117 light-years away in the constellation Cetus. It was first spotted by the Transiting Exoplanet Survey Satellite (TESS) in 2019 and confirmed as a planet in 2025 after follow-up observations.
How it orbits and how big it is
- Orbital period: about 0.224 days (5.4 hours), making it one of the shortest-period planets known.
- Distance from its star: about 0.0063 AU (roughly 940,000 km).
- Orbit: nearly circular and viewed edge-on from Earth (inclination around 74 degrees).
- Size and mass: radius about 1.54 times Earth’s; mass about 6.2 Earth masses.
- Density: around 9.4 g/cm³, pointing to a rocky composition.
What it’s like on TOI-2431 b
- Temperature: extremely hot, with an equilibrium temperature near 2063 K (about 1790°C).
- Dayside conditions: likely molten lava; any atmosphere would be made of rock vapors.
- Atmosphere detection: its close, bright-star host makes it a good target for future atmospheric studies with telescopes like the James Webb Space Telescope.
Fate of the planet
- The planet is so close to its star that its orbit is slowly decaying. It is expected to be torn apart by the star in about 31 million years when it reaches the star’s Roche lobe.
About the star
- TOI-2431 (HIP 11707) is a K-type main-sequence star in Cetus, about 117 light-years away.
- It has roughly 0.66 solar masses and 0.65 solar radii, with an effective temperature around 4109 K and luminosity about 11% that of the Sun.
- Its visible magnitude is 10.89, meaning it can’t be seen with the naked eye.
This page was last edited on 2 February 2026, at 13:03 (CET).