Kepler-302 b
Astrophysical Synthesis & Habitability Characterization
Kepler-302 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-302, located approximately 4574.6 light-years (1402.58 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0931% across the stellar disk), this world measures 4.06 Earth radii (0.36 Jupiter radii) and has a measured mass of 15.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.94 g⊕ (9.22 m/s²), and an escape velocity of 21.9 km/s.
In its orbital architecture around Kepler-302, Kepler-302 b completes one full revolution every 30.184 Earth days at a semi-major axis of 0.193 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 69.6 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 634 K (+361°C / +682°F) and receiving 31.25 S⊕ (~42,527 W/m²), Kepler-302 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-302 is classified as a stellar host with an effective photospheric temperature of 5,740 K, a radius of 1.22 R☉, a mass of 1.021 M☉, an estimated bolometric luminosity of 1.45 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, Kepler-302 shines at apparent V-band magnitude 15.694 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-302 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-302 b sharing its stellar neighborhood alongside Kepler-302 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-302 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,740 K |
| Stellar Radius | 1.2200 R☉ |
| Stellar Mass | 1.0210 M☉ |
| Bolometric Luminosity | 1.45 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 4.470 Gyr |
| Apparent Magnitude | V: 15.694 · G: 15.491 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.193000 AU |
| Orbital Period | 30.184 days |
| Mean Orbital Velocity | 69.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9800° |
| Mean Bulk Density | 1.28 g/cm³ (21.9 km/s vesc) |
| Insolation Flux | 31.2470 S⊕ (~42,527 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4574.600 LY (1402.580 pc) |