Kepler-23 c
Astrophysical Synthesis & Habitability Characterization
Kepler-23 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-23, located approximately 2725.9 light-years (835.76 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0317% across the stellar disk), this world measures 3.005 Earth radii (0.27 Jupiter radii) and has a measured mass of 7.81 Earth masses. Combining its mass and radius yields a mean bulk density of 1.59 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.86 g⊕ (8.43 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around Kepler-23, Kepler-23 c completes one full revolution every 10.74 Earth days at a semi-major axis of 0.09501 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.021 (ranging from 0.093 AU at periapsis to 0.097 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1008 K (+735°C / +1355°F) and receiving 257.39 S⊕ (~350,308 W/m²), Kepler-23 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-23 is classified as a stellar host with an effective photospheric temperature of 5,828 K, a radius of 1.548 R☉, a mass of 1.078 M☉, an estimated bolometric luminosity of 2.48 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.12 Gyr and a metallicity of [Fe/H] = -0.112 dex (metal-poor relative to the Sun). From Earth, Kepler-23 shines at apparent V-band magnitude 13.567 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-23 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-23 c sharing its stellar neighborhood alongside Kepler-23 b, Kepler-23 d.
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-23 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,828 K |
| Stellar Radius | 1.5480 R☉ |
| Stellar Mass | 1.0780 M☉ |
| Bolometric Luminosity | 2.48 L☉ |
| Metallicity [Fe/H] | -0.112 dex |
| Stellar Age | 9.120 Gyr |
| Apparent Magnitude | V: 13.567 · G: 13.402 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.095010 AU |
| Orbital Period | 10.74 days |
| Mean Orbital Velocity | 96.2 km/s |
| Orbital Eccentricity (e) | 0.02100 |
| Orbital Inclination (i) | 89.8600° |
| Mean Bulk Density | 1.59 g/cm³ (18 km/s vesc) |
| Insolation Flux | 257.3900 S⊕ (~350,308 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2725.900 LY (835.756 pc) |