Kepler-118 c
Astrophysical Synthesis & Habitability Characterization
Kepler-118 c is a confirmed gas giant exoplanet orbiting the star Kepler-118, located approximately 1872.9 light-years (574.23 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.4142% across the stellar disk), this world measures 7.68 Earth radii (0.69 Jupiter radii) and has a measured mass of 45.7 Earth masses (0.14 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.56 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.77 g⊕ (7.55 m/s²), and an escape velocity of 27.3 km/s.
In its orbital architecture around Kepler-118, Kepler-118 c completes one full revolution every 20.172 Earth days at a semi-major axis of 0.141 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 76 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 564 K (+291°C / +556°F) and receiving 21.41 S⊕ (~29,138 W/m²), Kepler-118 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-118 is classified as a stellar host with an effective photospheric temperature of 5,274 K, a radius of 1.094 R☉, a mass of 0.811 M☉, an estimated bolometric luminosity of 0.831 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = 0.18 dex (metal-rich relative to the Sun). From Earth, Kepler-118 shines at apparent V-band magnitude 14.867 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-118 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-118 c sharing its stellar neighborhood alongside Kepler-118 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-118 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,274 K |
| Stellar Radius | 1.0940 R☉ |
| Stellar Mass | 0.8110 M☉ |
| Bolometric Luminosity | 0.831 L☉ |
| Metallicity [Fe/H] | 0.180 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 14.867 · G: 14.719 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.141000 AU |
| Orbital Period | 20.172 days |
| Mean Orbital Velocity | 76 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.6100° |
| Mean Bulk Density | 0.56 g/cm³ (27.3 km/s vesc) |
| Insolation Flux | 21.4090 S⊕ (~29,138 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1872.900 LY (574.228 pc) |