GJ 367 b

GJ 367 b, officially named Tahay, is a sub-Earth exoplanet orbiting the red dwarf star GJ 367 (Añañuca), located about 30.7 light-years away in the constellation Vela. Discovered in 2021 by NASA’s TESS mission, it’s one of the smallest and densest exoplanets known within 10 parsecs of Earth.

Orbital & Physical Characteristics

• 🔄 Orbital Period: ~7.7 hours (one of the shortest known)

• 📏 Distance from Star: ~0.00709 AU

• 📐 Radius: ~0.7 Earth radii

• ⚖️ Mass: ~0.63 Earth masses

• 🧊 Density: ~10.2 g/cm³ — denser than Earth, similar to Mercury

• 🌡️ Temperature:

  • Dayside: ~1,728 K (1,455°C / 2,651°F)

  • Nightside: <847 K (574°C / 1,065°F)

Atmospheric Status

• ❌ No detectable atmosphere: JWST observations suggest any atmosphere has boiled away due to intense stellar radiation

• 🌬️ Volatile loss: No heat transfer between day and night sides implies a bare, rocky surface

Scientific Significance

• 🧪 Core composition: Likely made of iron and nickel, similar to Mercury

• 🌠 Formation theories:

  • Mantle evaporation from extreme heat

  • Giant impact stripping away lighter elements

  • Formation inside the snow line with low volatiles

• 🌸 Name origin: “Tahay” is a Chilean wildflower that blooms for 7–8 hours—mirroring the planet’s orbital period