GJ 163 d
Astrophysical Synthesis & Habitability Characterization
GJ 163 d 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 5.92 Earth radii (0.53 Jupiter radii) and has a measured mass of 29.4 Earth masses. Combining its mass and radius yields a mean bulk density of 0.78 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.84 g⊕ (8.24 m/s²), and an escape velocity of 24.9 km/s.
In its orbital architecture around GJ 163, GJ 163 d completes one full revolution every 603.951 Earth days (1.65Julian years) at a semi-major axis of 1.0304 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 18.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.373, swinging from 0.6461 AU at periapsis out to 1.4147 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 106 K (-167°C / -269°F) and an incident flux of 0.02 S⊕ (~25 W/m²), surface water and volatile species on GJ 163 d would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
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 d sharing its stellar neighborhood alongside GJ 163 b, GJ 163 c.
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) | 1.030400 AU |
| Orbital Period | 603.951 days |
| Mean Orbital Velocity | 18.6 km/s |
| Orbital Eccentricity (e) | 0.37300 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.78 g/cm³ (24.9 km/s vesc) |
| Insolation Flux | 0.0184 S⊕ (~25 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 49.300 LY (15.129 pc) |