Kepler-188 c
Astrophysical Synthesis & Habitability Characterization
Kepler-188 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-188, located approximately 3159 light-years (968.54 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0657% across the stellar disk), this world measures 3.19 Earth radii (0.28 Jupiter radii) and has a measured mass of 10.3 Earth masses. Combining its mass and radius yields a mean bulk density of 1.75 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.01 g⊕ (9.9 m/s²), and an escape velocity of 20.1 km/s.
In its orbital architecture around Kepler-188, Kepler-188 c completes one full revolution every 5.997 Earth days at a semi-major axis of 0.066 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 119.7 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 1025 K (+752°C / +1386°F) and receiving 257.35 S⊕ (~350,251 W/m²), Kepler-188 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-188 is classified as a stellar host with an effective photospheric temperature of 6,021 K, a radius of 1.141 R☉, a mass of 1.021 M☉, an estimated bolometric luminosity of 1.535 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.8 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, Kepler-188 shines at apparent V-band magnitude 14.719 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-188 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-188 c sharing its stellar neighborhood alongside Kepler-188 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-188 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,021 K |
| Stellar Radius | 1.1410 R☉ |
| Stellar Mass | 1.0210 M☉ |
| Bolometric Luminosity | 1.535 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 5.800 Gyr |
| Apparent Magnitude | V: 14.719 · G: 14.634 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.066000 AU |
| Orbital Period | 5.997 days |
| Mean Orbital Velocity | 119.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.6300° |
| Mean Bulk Density | 1.75 g/cm³ (20.1 km/s vesc) |
| Insolation Flux | 257.3480 S⊕ (~350,251 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3159.000 LY (968.544 pc) |