Overview

• Astronomers confirmed TOI-6894b with TESS transit data and ground-based follow-ups, publishing the discovery in Nature Astronomy on June 5, 2025.
• The exoplanet weighs about 53 Earth masses—roughly half that of Saturn—but completes an orbit every 3.3 days at just 1/40 the Earth-Sun distance, giving it extremely low density and high temperatures.
• Its host, TOI-6894, is a red dwarf with only 0.2 solar masses and 20 percent of the Sun’s radius, making it the smallest known star to host such a large gas planet.
• Standard core-accretion and disk-instability scenarios cannot fully account for the planet’s growth around a low-mass star, prompting a reevaluation of planet-formation theories.
• The James Webb Space Telescope will use high-resolution infrared spectroscopy to analyze TOI-6894b’s atmosphere and investigate the origins of this unexpected gas giant.