Kepler-266 c
Astrophysical Synthesis & Habitability Characterization
Kepler-266 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-266, located approximately 4470.9 light-years (1370.79 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1204% across the stellar disk), this world measures 3.89 Earth radii (0.35 Jupiter radii) and has a measured mass of 14.4 Earth masses. Combining its mass and radius yields a mean bulk density of 1.35 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.95 g⊕ (9.32 m/s²), and an escape velocity of 21.5 km/s.
In its orbital architecture around Kepler-266, Kepler-266 c completes one full revolution every 107.724 Earth days at a semi-major axis of 0.457 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 46.2 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 421 K (+148°C / +298°F) and receiving 5.59 S⊕ (~7,611 W/m²), Kepler-266 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-266 is classified as a stellar host with an effective photospheric temperature of 5,885 K, a radius of 1.028 R☉, a mass of 0.947 M☉, an estimated bolometric luminosity of 1.137 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.79 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, Kepler-266 shines at apparent V-band magnitude 15.787 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-266 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-266 c sharing its stellar neighborhood alongside Kepler-266 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-266 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,885 K |
| Stellar Radius | 1.0280 R☉ |
| Stellar Mass | 0.9470 M☉ |
| Bolometric Luminosity | 1.137 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 4.790 Gyr |
| Apparent Magnitude | V: 15.787 · G: 15.577 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.457000 AU |
| Orbital Period | 107.724 days |
| Mean Orbital Velocity | 46.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 90.0000° |
| Mean Bulk Density | 1.35 g/cm³ (21.5 km/s vesc) |
| Insolation Flux | 5.5920 S⊕ (~7,611 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4470.900 LY (1370.790 pc) |