TRAPPIST-1 f

Astrophysical Synthesis & Habitability Characterization

TRAPPIST-1 f is a confirmed terrestrial exoplanet orbiting the star TRAPPIST-1, located approximately 40.5 light-years (12.43 parsecs) from the Solar System. First announced in 2017 by Multiple Observatories using the Transit detection technique (producing an estimated primary transit depth of 0.646% across the stellar disk), this world measures 1.045 Earth radii and has a measured mass of 1.039 Earth masses. Combining its mass and radius yields a mean bulk density of 5.02 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.95 g⊕ (9.32 m/s²), and an escape velocity of 11.2 km/s.

In its orbital architecture around TRAPPIST-1, TRAPPIST-1 f completes one full revolution every 9.208 Earth days at a semi-major axis of 0.03849 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 45.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.01007 (ranging from 0.0381 AU at periapsis to 0.0389 AU at apoapsis), the planet experiences minimal orbital distance variation.

✓ Classified as a Temperate Habitable Zone Candidate.

With an estimated equilibrium temperature of 218 K (-55°C / -67°F) and an incident stellar irradiance of 0.37 S⊕ (~508 W/m²), TRAPPIST-1 f orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.

The host star TRAPPIST-1 is classified as a low-mass red dwarf of spectral type M8.0 V with an effective photospheric temperature of 2,566 K, a radius of 0.1192 R☉, a mass of 0.0898 M☉, an estimated bolometric luminosity of 0.00055 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.6 Gyr and a metallicity of [Fe/H] = 0.052 dex (metal-rich relative to the Sun). From Earth, TRAPPIST-1 shines at apparent V-band magnitude 17.02 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TRAPPIST-1 system is a multi-planet architecture hosting 7 confirmed worlds, with TRAPPIST-1 f sharing its stellar neighborhood alongside TRAPPIST-1 b, TRAPPIST-1 c, TRAPPIST-1 d, TRAPPIST-1 e, TRAPPIST-1 g, TRAPPIST-1 h.

Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).