Kepler-869 b
Astrophysical Synthesis & Habitability Characterization
Kepler-869 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-869, located approximately 3064.1 light-years (939.46 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1214% across the stellar disk), this world measures 3.61 Earth radii (0.32 Jupiter radii) and has a measured mass of 12.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.49 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21 km/s.
In its orbital architecture around Kepler-869, Kepler-869 b completes one full revolution every 40.429 Earth days at a semi-major axis of 0.2244 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 60.4 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 494 K (+221°C / +430°F) and receiving 17.23 S⊕ (~23,455 W/m²), Kepler-869 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-869 is classified as a stellar host with an effective photospheric temperature of 5,664 K, a radius of 0.95 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.833 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.79 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-869 shines at apparent V-band magnitude 15.122 (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-869 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,664 K |
| Stellar Radius | 0.9500 R☉ |
| Stellar Mass | 0.9700 M☉ |
| Bolometric Luminosity | 0.833 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 4.790 Gyr |
| Apparent Magnitude | V: 15.122 · G: 14.969 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.224400 AU |
| Orbital Period | 40.429 days |
| Mean Orbital Velocity | 60.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.9200° |
| Mean Bulk Density | 1.49 g/cm³ (21 km/s vesc) |
| Insolation Flux | 17.2340 S⊕ (~23,455 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3064.100 LY (939.455 pc) |