Kepler-233 c
Astrophysical Synthesis & Habitability Characterization
Kepler-233 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-233, located approximately 2793.3 light-years (856.42 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1074% across the stellar disk), this world measures 2.71 Earth radii and has a measured mass of 7.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.16 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19 km/s.
In its orbital architecture around Kepler-233, Kepler-233 c completes one full revolution every 60.419 Earth days at a semi-major axis of 0.287 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 51.7 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 390 K (+117°C / +243°F) and receiving 6.20 S⊕ (~8,431 W/m²), Kepler-233 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-233 is classified as a stellar host with an effective photospheric temperature of 5,360 K, a radius of 0.758 R☉, a mass of 0.855 M☉, an estimated bolometric luminosity of 0.425 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.6 Gyr and a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, Kepler-233 shines at apparent V-band magnitude 15.477 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-233 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-233 c sharing its stellar neighborhood alongside Kepler-233 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-233 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,360 K |
| Stellar Radius | 0.7580 R☉ |
| Stellar Mass | 0.8550 M☉ |
| Bolometric Luminosity | 0.425 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | 0.600 Gyr |
| Apparent Magnitude | V: 15.477 · G: 15.326 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.287000 AU |
| Orbital Period | 60.419 days |
| Mean Orbital Velocity | 51.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9400° |
| Mean Bulk Density | 2.16 g/cm³ (19 km/s vesc) |
| Insolation Flux | 6.1950 S⊕ (~8,431 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2793.300 LY (856.417 pc) |