Kepler-856 b

Astrophysical Synthesis & Habitability Characterization

Kepler-856 b is a confirmed gas giant exoplanet orbiting the star Kepler-856, located approximately 4406.9 light-years (1351.17 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.8405% across the stellar disk), this world measures 9.3 Earth radii (0.83 Jupiter radii) and has a measured mass of 63.3 Earth masses (0.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.73 g⊕ (7.16 m/s²), and an escape velocity of 29.2 km/s.

In its orbital architecture around Kepler-856, Kepler-856 b completes one full revolution every 8.028 Earth days at a semi-major axis of 0.0787 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 106.7 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 824 K (+551°C / +1024°F) and receiving 153.50 S⊕ (~208,909 W/m²), Kepler-856 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-856 is classified as a stellar host with an effective photospheric temperature of 5,535 K, a radius of 0.93 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 0.728 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.27 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-856 shines at apparent V-band magnitude 15.594 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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