Kepler-475 b
Astrophysical Synthesis & Habitability Characterization
Kepler-475 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-475, located approximately 913.5 light-years (280.07 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0835% across the stellar disk), this world measures 2.49 Earth radii and has a measured mass of 6.76 Earth masses. Combining its mass and radius yields a mean bulk density of 2.41 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 18.4 km/s.
In its orbital architecture around Kepler-475, Kepler-475 b completes one full revolution every 3.106 Earth days at a semi-major axis of 0.03989 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 139.7 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 980 K (+707°C / +1305°F) and receiving 215.46 S⊕ (~293,244 W/m²), Kepler-475 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-475 is classified as a stellar host with an effective photospheric temperature of 5,009 K, a radius of 0.79 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.352 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.69 Gyr and a metallicity of [Fe/H] = 0.21 dex (metal-rich relative to the Sun). From Earth, Kepler-475 shines at apparent V-band magnitude 13.512 (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-475 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,009 K |
| Stellar Radius | 0.7900 R☉ |
| Stellar Mass | 0.8600 M☉ |
| Bolometric Luminosity | 0.352 L☉ |
| Metallicity [Fe/H] | 0.210 dex |
| Stellar Age | 2.690 Gyr |
| Apparent Magnitude | V: 13.512 · G: 13.316 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.039890 AU |
| Orbital Period | 3.106 days |
| Mean Orbital Velocity | 139.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.8500° |
| Mean Bulk Density | 2.41 g/cm³ (18.4 km/s vesc) |
| Insolation Flux | 215.4620 S⊕ (~293,244 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 913.500 LY (280.069 pc) |