Kepler-133 c
Astrophysical Synthesis & Habitability Characterization
Kepler-133 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-133, located approximately 2131.8 light-years (653.6 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0334% across the stellar disk), this world measures 2.84 Earth radii and has a measured mass of 8.45 Earth masses. Combining its mass and radius yields a mean bulk density of 2.03 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.3 km/s.
In its orbital architecture around Kepler-133, Kepler-133 c completes one full revolution every 31.518 Earth days at a semi-major axis of 0.204 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 70.4 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 663 K (+390°C / +734°F) and receiving 67.16 S⊕ (~91,406 W/m²), Kepler-133 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-133 is classified as a stellar host with an effective photospheric temperature of 5,736 K, a radius of 1.425 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 1.972 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.03 Gyr and a metallicity of [Fe/H] = 0.282 dex (metal-rich relative to the Sun). From Earth, Kepler-133 shines at apparent V-band magnitude 12.896 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-133 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-133 c sharing its stellar neighborhood alongside Kepler-133 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-133 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,736 K |
| Stellar Radius | 1.4250 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 1.972 L☉ |
| Metallicity [Fe/H] | 0.282 dex |
| Stellar Age | 6.030 Gyr |
| Apparent Magnitude | V: 12.896 · G: 12.842 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.204000 AU |
| Orbital Period | 31.518 days |
| Mean Orbital Velocity | 70.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.8000° |
| Mean Bulk Density | 2.03 g/cm³ (19.3 km/s vesc) |
| Insolation Flux | 67.1610 S⊕ (~91,406 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2131.800 LY (653.600 pc) |