Kepler-609 b

Astrophysical Synthesis & Habitability Characterization

Kepler-609 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-609, located approximately 3476.2 light-years (1065.82 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0726% across the stellar disk), this world measures 3.35 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.64 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.5 km/s.

In its orbital architecture around Kepler-609, Kepler-609 b completes one full revolution every 6.521 Earth days at a semi-major axis of 0.0682 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 113.8 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 932 K (+659°C / +1218°F) and receiving 258.06 S⊕ (~351,218 W/m²), Kepler-609 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-609 is classified as a stellar host with an effective photospheric temperature of 5,971 K, a radius of 1.14 R☉, a mass of 1.09 M☉, an estimated bolometric luminosity of 1.482 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.72 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, Kepler-609 shines at apparent V-band magnitude 14.96 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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