Kepler-427 b
Astrophysical Synthesis & Habitability Characterization
Kepler-427 b is a confirmed gas giant exoplanet orbiting the star Kepler-427, located approximately 3319.6 light-years (1017.8 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.877% across the stellar disk), this world measures 13.79 Earth radii (1.23 Jupiter radii) and has a measured mass of 92.17 Earth masses (0.29 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.19 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.48 g⊕ (4.71 m/s²), and an escape velocity of 28.9 km/s.
In its orbital architecture around Kepler-427, Kepler-427 b completes one full revolution every 10.291 Earth days at a semi-major axis of 0.091 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 96.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.57, swinging from 0.0391 AU at periapsis out to 0.1429 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1100 K (+827°C / +1521°F) and receiving 208.72 S⊕ (~284,069 W/m²), Kepler-427 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-427 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,800 K, a radius of 1.35 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 1.85 L☉. Stellar evolution modeling indicates an estimated stellar age of 7 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, Kepler-427 shines at apparent V-band magnitude 14.301 (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-427 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,800 K |
| Stellar Radius | 1.3500 R☉ |
| Stellar Mass | 0.9600 M☉ |
| Bolometric Luminosity | 1.85 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 7.000 Gyr |
| Apparent Magnitude | V: 14.301 · G: 14.196 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091000 AU |
| Orbital Period | 10.291 days |
| Mean Orbital Velocity | 96.2 km/s |
| Orbital Eccentricity (e) | 0.57000 |
| Orbital Inclination (i) | 89.5000° |
| Mean Bulk Density | 0.19 g/cm³ (28.9 km/s vesc) |
| Insolation Flux | 208.7210 S⊕ (~284,069 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3319.600 LY (1017.800 pc) |