TRAPPIST-1 e
Astrophysical Synthesis & Habitability Characterization
TRAPPIST-1 e 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 0.5007% across the stellar disk), this world measures 0.92 Earth radii and has a measured mass of 0.692 Earth masses. Combining its mass and radius yields a mean bulk density of 4.9 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.82 g⊕ (8.04 m/s²), and an escape velocity of 9.7 km/s.
In its orbital architecture around TRAPPIST-1, TRAPPIST-1 e completes one full revolution every 6.101 Earth days at a semi-major axis of 0.02925 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 52.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0051 (ranging from 0.0291 AU at periapsis to 0.0294 AU at apoapsis), the planet experiences minimal orbital distance variation.
✓ Classified as a Temperate Habitable Zone Candidate.
With an estimated equilibrium temperature of 250 K (-23°C / -9°F) and an incident stellar irradiance of 0.65 S⊕ (~879 W/m²), TRAPPIST-1 e 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 e sharing its stellar neighborhood alongside TRAPPIST-1 b, TRAPPIST-1 c, TRAPPIST-1 d, TRAPPIST-1 f, TRAPPIST-1 g, TRAPPIST-1 h.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TRAPPIST-1 |
| Spectral Type | M8.0 V |
| Effective Temp (Teff) | 2,566 K |
| Stellar Radius | 0.1192 R☉ |
| Stellar Mass | 0.0898 M☉ |
| Bolometric Luminosity | 0.00055 L☉ |
| Metallicity [Fe/H] | 0.052 dex |
| Stellar Age | 7.600 Gyr |
| Apparent Magnitude | V: 17.020 · G: 15.645 |
| System Architecture | 1 Star, 7 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.029250 AU |
| Orbital Period | 6.101 days |
| Mean Orbital Velocity | 52.2 km/s |
| Orbital Eccentricity (e) | 0.00510 |
| Orbital Inclination (i) | 89.7930° |
| Mean Bulk Density | 4.9 g/cm³ (9.7 km/s vesc) |
| Insolation Flux | 0.6460 S⊕ (~879 W/m²) |
| Habitable Zone Status | ★ Temperate Zone |
| Celestial Distance | 40.500 LY (12.430 pc) |