Kepler-447 b
Astrophysical Synthesis & Habitability Characterization
Kepler-447 b is a confirmed gas giant exoplanet orbiting the star Kepler-447, located approximately 874.2 light-years (268.04 parsecs) from the Solar System. First announced in 2015 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 2.6064% across the stellar disk), this world measures 18.49 Earth radii (1.65 Jupiter radii) and has a measured mass of 435.41 Earth masses (1.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.38 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.27 g⊕ (12.45 m/s²), and an escape velocity of 54.3 km/s.
In its orbital architecture around Kepler-447, Kepler-447 b completes one full revolution every 7.794 Earth days at a semi-major axis of 0.0769 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 107.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.123 carries the world between 0.0674 AU at periapsis and 0.0864 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 882 K (+609°C / +1128°F) and receiving 119.04 S⊕ (~162,012 W/m²), Kepler-447 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-447 is classified as a solar-type yellow star of spectral type G8 V with an effective photospheric temperature of 5,493 K, a radius of 1.05 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 0.901 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.62 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, Kepler-447 shines at apparent V-band magnitude 12.52 (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-447 |
| Spectral Type | G8 V |
| Effective Temp (Teff) | 5,493 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 0.901 L☉ |
| Metallicity [Fe/H] | 0.070 dex |
| Stellar Age | 1.620 Gyr |
| Apparent Magnitude | V: 12.520 · G: 12.380 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.076900 AU |
| Orbital Period | 7.794 days |
| Mean Orbital Velocity | 107.3 km/s |
| Orbital Eccentricity (e) | 0.12300 |
| Orbital Inclination (i) | 86.5500° |
| Mean Bulk Density | 0.38 g/cm³ (54.3 km/s vesc) |
| Insolation Flux | 119.0390 S⊕ (~162,012 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 874.200 LY (268.041 pc) |