Kepler-318 c
Astrophysical Synthesis & Habitability Characterization
Kepler-318 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-318, located approximately 1595.4 light-years (489.14 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0805% across the stellar disk), this world measures 3.68 Earth radii (0.33 Jupiter radii) and has a measured mass of 13.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.45 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21.1 km/s.
In its orbital architecture around Kepler-318, Kepler-318 c completes one full revolution every 11.815 Earth days at a semi-major axis of 0.105 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.7 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 762 K (+489°C / +912°F) and receiving 96.51 S⊕ (~131,354 W/m²), Kepler-318 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-318 is classified as a stellar host with an effective photospheric temperature of 5,746 K, a radius of 1.189 R☉, a mass of 1.073 M☉, an estimated bolometric luminosity of 1.383 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.95 Gyr and a metallicity of [Fe/H] = 0.332 dex (metal-rich relative to the Sun). From Earth, Kepler-318 shines at apparent V-band magnitude 13.442 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-318 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-318 c sharing its stellar neighborhood alongside Kepler-318 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: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-318 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,746 K |
| Stellar Radius | 1.1890 R☉ |
| Stellar Mass | 1.0730 M☉ |
| Bolometric Luminosity | 1.383 L☉ |
| Metallicity [Fe/H] | 0.332 dex |
| Stellar Age | 0.950 Gyr |
| Apparent Magnitude | V: 13.442 · G: 13.281 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.105000 AU |
| Orbital Period | 11.815 days |
| Mean Orbital Velocity | 96.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.1500° |
| Mean Bulk Density | 1.45 g/cm³ (21.1 km/s vesc) |
| Insolation Flux | 96.5130 S⊕ (~131,354 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1595.400 LY (489.141 pc) |