Kepler-268 c
Astrophysical Synthesis & Habitability Characterization
Kepler-268 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-268, located approximately 2778.4 light-years (851.87 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0592% across the stellar disk), this world measures 3.38 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.4 Earth masses. Combining its mass and radius yields a mean bulk density of 1.63 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.5 km/s.
In its orbital architecture around Kepler-268, Kepler-268 c completes one full revolution every 83.446 Earth days at a semi-major axis of 0.391 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 51 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 471 K (+198°C / +388°F) and receiving 13.66 S⊕ (~18,594 W/m²), Kepler-268 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-268 is classified as a stellar host with an effective photospheric temperature of 6,081 K, a radius of 1.274 R☉, a mass of 1.109 M☉, an estimated bolometric luminosity of 1.991 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.71 Gyr and a metallicity of [Fe/H] = 0.001 dex (near-solar heavy-element abundance). From Earth, Kepler-268 shines at apparent V-band magnitude 13.844 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-268 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-268 c sharing its stellar neighborhood alongside Kepler-268 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-268 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,081 K |
| Stellar Radius | 1.2740 R☉ |
| Stellar Mass | 1.1090 M☉ |
| Bolometric Luminosity | 1.991 L☉ |
| Metallicity [Fe/H] | 0.001 dex |
| Stellar Age | 1.710 Gyr |
| Apparent Magnitude | V: 13.844 · G: 13.668 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.391000 AU |
| Orbital Period | 83.446 days |
| Mean Orbital Velocity | 51 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9700° |
| Mean Bulk Density | 1.63 g/cm³ (20.5 km/s vesc) |
| Insolation Flux | 13.6620 S⊕ (~18,594 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2778.400 LY (851.870 pc) |