Kepler-867 b

Astrophysical Synthesis & Habitability Characterization

Kepler-867 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-867, located approximately 3899.3 light-years (1195.54 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2185% across the stellar disk), this world measures 4.64 Earth radii (0.41 Jupiter radii) and has a measured mass of 19.4 Earth masses. Combining its mass and radius yields a mean bulk density of 1.07 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 22.9 km/s.

In its orbital architecture around Kepler-867, Kepler-867 b completes one full revolution every 150.242 Earth days at a semi-major axis of 0.5375 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 38.9 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.

☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 4.640 R⊕, Kepler-867 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.

The host star Kepler-867 is classified as a stellar host with an effective photospheric temperature of 5,541 K, a radius of 0.91 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.7 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.89 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-867 shines at apparent V-band magnitude 15.098 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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