GJ 163 c
Astrophysical Synthesis & Habitability Characterization
GJ 163 c is a confirmed sub-neptune exoplanet orbiting the star GJ 163, located approximately 49.3 light-years (15.13 parsecs) from the Solar System. First announced in 2013 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.5 Earth radii and has a measured mass of 6.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.4 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.4 km/s.
In its orbital architecture around GJ 163, GJ 163 c completes one full revolution every 25.631 Earth days at a semi-major axis of 0.1254 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 53.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.099 carries the world between 0.113 AU at periapsis and 0.1378 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.500 R⊕, GJ 163 c 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 163 is classified as a low-mass red dwarf of spectral type M with an effective photospheric temperature of 3,500 K, a radius of 0.4097 R☉, a mass of 0.4 M☉, an estimated bolometric luminosity of 0.023 L☉. Stellar evolution modeling indicates an estimated stellar age of 6 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, GJ 163 shines at apparent V-band magnitude 11.79 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The GJ 163 system is a multi-planet architecture hosting 3 confirmed worlds, with GJ 163 c sharing its stellar neighborhood alongside GJ 163 b, GJ 163 d.
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 163 |
| Spectral Type | M |
| Effective Temp (Teff) | 3,500 K |
| Stellar Radius | 0.4097 R☉ |
| Stellar Mass | 0.4000 M☉ |
| Bolometric Luminosity | 0.023 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 6.000 Gyr |
| Apparent Magnitude | V: 11.790 · G: 10.677 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.125400 AU |
| Orbital Period | 25.631 days |
| Mean Orbital Velocity | 53.2 km/s |
| Orbital Eccentricity (e) | 0.09900 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.4 g/cm³ (18.4 km/s vesc) |
| Insolation Flux | 1.2457 S⊕ (~1,695 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 49.300 LY (15.129 pc) |