GJ 667 C b
Astrophysical Synthesis & Habitability Characterization
GJ 667 C b is a confirmed sub-neptune exoplanet orbiting the star GJ 667 C, located approximately 23.6 light-years (7.24 parsecs) from the Solar System. First announced in 2012 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.25 Earth radii and has a measured mass of 5.68 Earth masses. Combining its mass and radius yields a mean bulk density of 2.75 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around GJ 667 C, GJ 667 C b completes one full revolution every 7.203 Earth days at a semi-major axis of 0.050431 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 76.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2 carries the world between 0.0403 AU at periapsis and 0.0605 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.250 R⊕, GJ 667 C b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star GJ 667 C is classified as a low-mass red dwarf of spectral type M1.5 V with an effective photospheric temperature of 3,350 K, a mass of 0.33 M☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = -0.55 dex (metal-poor relative to the Sun). From Earth, GJ 667 C shines at apparent V-band magnitude 10.602 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The GJ 667 C system is a multi-planet architecture hosting 5 confirmed worlds, with GJ 667 C b sharing its stellar neighborhood alongside GJ 667 C c, GJ 667 C f, GJ 667 C e, GJ 667 C g.
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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 667 C |
| Spectral Type | M1.5 V |
| Effective Temp (Teff) | 3,350 K |
| Stellar Radius | — |
| Stellar Mass | 0.3300 M☉ |
| Metallicity [Fe/H] | -0.550 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 10.602 · G: 9.380 |
| System Architecture | 3 Stars, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050431 AU |
| Orbital Period | 7.203 days |
| Mean Orbital Velocity | 76.2 km/s |
| Orbital Eccentricity (e) | 0.20000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.75 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 5.3902 S⊕ (~7,336 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 23.600 LY (7.244 pc) |