Kepler-69 b
Astrophysical Synthesis & Habitability Characterization
Kepler-69 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-69, located approximately 2383 light-years (730.63 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0488% across the stellar disk), this world measures 2.24 Earth radii and has a measured mass of 5.65 Earth masses. Combining its mass and radius yields a mean bulk density of 2.77 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-69, Kepler-69 b completes one full revolution every 13.722 Earth days at a semi-major axis of 0.094 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 74.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.16 carries the world between 0.079 AU at periapsis and 0.109 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 779 K (+506°C / +943°F) and receiving 123.52 S⊕ (~168,107 W/m²), Kepler-69 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-69 is classified as a solar-type yellow star of spectral type G4 V with an effective photospheric temperature of 5,638 K, a radius of 0.93 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.784 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.18 Gyr and a metallicity of [Fe/H] = -0.29 dex (metal-poor relative to the Sun). From Earth, Kepler-69 shines at apparent V-band magnitude 13.866 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-69 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-69 b sharing its stellar neighborhood alongside Kepler-69 c.
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-69 |
| Spectral Type | G4 V |
| Effective Temp (Teff) | 5,638 K |
| Stellar Radius | 0.9300 R☉ |
| Stellar Mass | 0.8100 M☉ |
| Bolometric Luminosity | 0.784 L☉ |
| Metallicity [Fe/H] | -0.290 dex |
| Stellar Age | 13.180 Gyr |
| Apparent Magnitude | V: 13.866 · G: 13.712 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.094000 AU |
| Orbital Period | 13.722 days |
| Mean Orbital Velocity | 74.5 km/s |
| Orbital Eccentricity (e) | 0.16000 |
| Orbital Inclination (i) | 89.6200° |
| Mean Bulk Density | 2.77 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 123.5170 S⊕ (~168,107 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2383.000 LY (730.625 pc) |