GJ 806 c
Astrophysical Synthesis & Habitability Characterization
GJ 806 c is a confirmed sub-neptune exoplanet orbiting the star GJ 806, located approximately 39.3 light-years (12.05 parsecs) from the Solar System. First announced in 2023 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.28 Earth radii and has a measured mass of 5.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.7 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 806, GJ 806 c completes one full revolution every 6.641 Earth days at a semi-major axis of 0.0523 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 85.7 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 490 K (+217°C / +423°F) and receiving 9.50 S⊕ (~12,930 W/m²), GJ 806 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star GJ 806 is classified as a low-mass red dwarf of spectral type M1.5 V with an effective photospheric temperature of 3,600 K, a radius of 0.4144 R☉, a mass of 0.413 M☉, an estimated bolometric luminosity of 0.026 L☉. Stellar evolution modeling indicates an estimated stellar age of 5 Gyr and a metallicity of [Fe/H] = -0.28 dex (metal-poor relative to the Sun). From Earth, GJ 806 shines at apparent V-band magnitude 10.79 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The GJ 806 system is a multi-planet architecture hosting 2 confirmed worlds, with GJ 806 c sharing its stellar neighborhood alongside GJ 806 b.
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 806 |
| Spectral Type | M1.5 V |
| Effective Temp (Teff) | 3,600 K |
| Stellar Radius | 0.4144 R☉ |
| Stellar Mass | 0.4130 M☉ |
| Bolometric Luminosity | 0.026 L☉ |
| Metallicity [Fe/H] | -0.280 dex |
| Stellar Age | 5.000 Gyr |
| Apparent Magnitude | V: 10.790 · G: 9.825 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.052300 AU |
| Orbital Period | 6.641 days |
| Mean Orbital Velocity | 85.7 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.7 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 9.5000 S⊕ (~12,930 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 39.300 LY (12.045 pc) |