Kepler-502 b

Astrophysical Synthesis & Habitability Characterization

Kepler-502 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-502, located approximately 5189.3 light-years (1591.04 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1285% across the stellar disk), this world measures 4.77 Earth radii (0.43 Jupiter radii) and has a measured mass of 20.4 Earth masses. Combining its mass and radius yields a mean bulk density of 1.04 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 23.1 km/s.

In its orbital architecture around Kepler-502, Kepler-502 b completes one full revolution every 4.287 Earth days at a semi-major axis of 0.0535 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 135.8 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 1217 K (+944°C / +1731°F) and receiving 859.51 S⊕ (~1,169,792 W/m²), Kepler-502 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-502 is classified as a stellar host with an effective photospheric temperature of 6,125 K, a radius of 1.22 R☉, a mass of 1.15 M☉, an estimated bolometric luminosity of 1.879 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.09 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, Kepler-502 shines at apparent V-band magnitude 15.136 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).