Kepler-866 b
Astrophysical Synthesis & Habitability Characterization
Kepler-866 b is a confirmed super-earth exoplanet orbiting the star Kepler-866, located approximately 2109.1 light-years (646.67 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0443% across the stellar disk), this world measures 1.63 Earth radii and has a measured mass of 3.29 Earth masses. Combining its mass and radius yields a mean bulk density of 4.19 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.24 g⊕ (12.16 m/s²), and an escape velocity of 15.9 km/s.
In its orbital architecture around Kepler-866, Kepler-866 b completes one full revolution every 2.617 Earth days at a semi-major axis of 0.0331 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 137.6 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 996 K (+723°C / +1333°F) and receiving 196.13 S⊕ (~266,929 W/m²), Kepler-866 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-866 is classified as a stellar host with an effective photospheric temperature of 4,751 K, a radius of 0.71 R☉, a mass of 0.75 M☉, an estimated bolometric luminosity of 0.23 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.27 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, Kepler-866 shines at apparent V-band magnitude 16.124 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-866 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,751 K |
| Stellar Radius | 0.7100 R☉ |
| Stellar Mass | 0.7500 M☉ |
| Bolometric Luminosity | 0.23 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | 4.270 Gyr |
| Apparent Magnitude | V: 16.124 · G: 15.797 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.033100 AU |
| Orbital Period | 2.617 days |
| Mean Orbital Velocity | 137.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.1500° |
| Mean Bulk Density | 4.19 g/cm³ (15.9 km/s vesc) |
| Insolation Flux | 196.1270 S⊕ (~266,929 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2109.100 LY (646.667 pc) |