Kepler-231 c
Astrophysical Synthesis & Habitability Characterization
Kepler-231 c is a confirmed super-earth exoplanet orbiting the star Kepler-231, located approximately 1032.7 light-years (316.62 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1304% across the stellar disk), this world measures 1.93 Earth radii and has a measured mass of 24.1 Earth masses. Combining its mass and radius yields a mean bulk density of 18.48 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 6.47 g⊕ (63.45 m/s²), and an escape velocity of 39.5 km/s.
In its orbital architecture around Kepler-231, Kepler-231 c completes one full revolution every 19.272 Earth days at a semi-major axis of 0.114 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 64.4 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 393 K (+120°C / +248°F) and receiving 6.27 S⊕ (~8,529 W/m²), Kepler-231 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-231 is classified as a low-mass red dwarf of spectral type M1 V with an effective photospheric temperature of 3,767 K, a radius of 0.49 R☉, a mass of 0.58 M☉, an estimated bolometric luminosity of 0.043 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.15 Gyr and a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, Kepler-231 shines at apparent V-band magnitude 15.813 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-231 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-231 c sharing its stellar neighborhood alongside Kepler-231 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-231 |
| Spectral Type | M1 V |
| Effective Temp (Teff) | 3,767 K |
| Stellar Radius | 0.4900 R☉ |
| Stellar Mass | 0.5800 M☉ |
| Bolometric Luminosity | 0.043 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | 3.150 Gyr |
| Apparent Magnitude | V: 15.813 · G: 15.390 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.114000 AU |
| Orbital Period | 19.272 days |
| Mean Orbital Velocity | 64.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9700° |
| Mean Bulk Density | 18.48 g/cm³ (39.5 km/s vesc) |
| Insolation Flux | 6.2670 S⊕ (~8,529 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1032.700 LY (316.618 pc) |