GJ 3222 b
Astrophysical Synthesis & Habitability Characterization
GJ 3222 b is a confirmed sub-neptune exoplanet orbiting the star GJ 3222, located approximately 59.5 light-years (18.24 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 3.4 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.442 Earth masses. Combining its mass and radius yields a mean bulk density of 1.61 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.99 g⊕ (9.71 m/s²), and an escape velocity of 20.5 km/s.
In its orbital architecture around GJ 3222, GJ 3222 b completes one full revolution every 10.667 Earth days at a semi-major axis of 0.091 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 92.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.929, swinging from 0.0065 AU at periapsis out to 0.1755 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 811 K (+538°C / +1000°F) and receiving 67.60 S⊕ (~91,997 W/m²), GJ 3222 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 3222 is classified as an orange K-type star of spectral type K0V with an effective photospheric temperature of 5,257 K, a radius of 0.9314 R☉, a mass of 0.89 M☉, an estimated bolometric luminosity of 0.594 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, GJ 3222 shines at apparent V-band magnitude 6.9 (accessible to binoculars and small amateur telescopes) in the Southern 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3222 |
| Spectral Type | K0V |
| Effective Temp (Teff) | 5,257 K |
| Stellar Radius | 0.9314 R☉ |
| Stellar Mass | 0.8900 M☉ |
| Bolometric Luminosity | 0.594 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 6.900 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091000 AU |
| Orbital Period | 10.667 days |
| Mean Orbital Velocity | 92.8 km/s |
| Orbital Eccentricity (e) | 0.92900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.61 g/cm³ (20.5 km/s vesc) |
| Insolation Flux | 67.5954 S⊕ (~91,997 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 59.500 LY (18.238 pc) |