Kepler-820 b

Astrophysical Synthesis & Habitability Characterization

Kepler-820 b is a confirmed gas giant exoplanet orbiting the star Kepler-820, located approximately 4524.4 light-years (1387.2 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1685% across the stellar disk), this world measures 6.09 Earth radii (0.54 Jupiter radii) and has a measured mass of 30.8 Earth masses (0.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.75 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.83 g⊕ (8.14 m/s²), and an escape velocity of 25.2 km/s.

In its orbital architecture around Kepler-820, Kepler-820 b completes one full revolution every 127.834 Earth days at a semi-major axis of 0.56004 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 47.7 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 554 K (+281°C / +538°F) and receiving 16.23 S⊕ (~22,086 W/m²), Kepler-820 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-820 is classified as a stellar host with an effective photospheric temperature of 6,260 K, a radius of 1.36 R☉, a mass of 1.23 M☉, an estimated bolometric luminosity of 2.548 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.63 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, Kepler-820 shines at apparent V-band magnitude 14.135 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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