GJ 1214 b
Astrophysical Synthesis & Habitability Characterization
GJ 1214 b is a confirmed sub-neptune exoplanet orbiting the star GJ 1214, located approximately 47.8 light-years (14.64 parsecs) from the Solar System. First announced in 2009 by MEarth Project using the Transit detection technique (producing an estimated primary transit depth of 1.3431% across the stellar disk), this world measures 2.733 Earth radii and has a measured mass of 8.41 Earth masses. Combining its mass and radius yields a mean bulk density of 2.27 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around GJ 1214, GJ 1214 b completes one full revolution every 1.58 Earth days at a semi-major axis of 0.01505 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 103.6 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0062 (ranging from 0.015 AU at periapsis to 0.0151 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 567 K (+294°C / +561°F) and receiving 17.20 S⊕ (~23,409 W/m²), GJ 1214 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 1214 is classified as a low-mass red dwarf of spectral type M4 V with an effective photospheric temperature of 3,101 K, a radius of 0.2162 R☉, a mass of 0.182 M☉, an estimated bolometric luminosity of 0.00388 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, GJ 1214 shines at apparent V-band magnitude 15.1 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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: MEarth Project · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 1214 |
| Spectral Type | M4 V |
| Effective Temp (Teff) | 3,101 K |
| Stellar Radius | 0.2162 R☉ |
| Stellar Mass | 0.1820 M☉ |
| Bolometric Luminosity | 0.00388 L☉ |
| Metallicity [Fe/H] | 0.240 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 15.100 · G: 13.009 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.015050 AU |
| Orbital Period | 1.58 days |
| Mean Orbital Velocity | 103.6 km/s |
| Orbital Eccentricity (e) | 0.00620 |
| Orbital Inclination (i) | 88.9800° |
| Mean Bulk Density | 2.27 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 17.2000 S⊕ (~23,409 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 47.800 LY (14.643 pc) |