Overview

• TOI-6894b is a low-density gas giant with a radius slightly exceeding Saturn’s and about half its mass, orbiting a star just one-fifth the Sun’s mass.
• Its host, TOI-6894, is the smallest star known to support a transiting giant exoplanet, challenging the assumption that low-mass stars lack sufficient disk material for such planets.
• Astronomers identified the planet using TESS transit signals and confirmed its mass through radial-velocity measurements from ESO’s Very Large Telescope.
• With an equilibrium temperature near 420 K, TOI-6894b is unusually cool for a gas giant and likely harbors a methane-dominated atmosphere.
• Scheduled JWST spectroscopy will probe key molecules such as methane and ammonia to determine whether the planet formed via core accretion or disk instability.