Kepler-891 b

Astrophysical Synthesis & Habitability Characterization

Kepler-891 b is a confirmed gas giant exoplanet orbiting the star Kepler-891, located approximately 7633.9 light-years (2340.58 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.3016% across the stellar disk), this world measures 6.41 Earth radii (0.57 Jupiter radii) and has a measured mass of 33.6 Earth masses (0.11 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.7 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.82 g⊕ (8.04 m/s²), and an escape velocity of 25.6 km/s.

In its orbital architecture around Kepler-891, Kepler-891 b completes one full revolution every 53.449 Earth days at a semi-major axis of 0.2881 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 58.6 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 486 K (+213°C / +415°F) and receiving 44.33 S⊕ (~60,328 W/m²), Kepler-891 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-891 is classified as a stellar host with an effective photospheric temperature of 5,887 K, a radius of 1.07 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.234 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.55 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, Kepler-891 shines at apparent V-band magnitude 15.386 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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