Kepler-409 b

Astrophysical Synthesis & Habitability Characterization

Kepler-409 b is a confirmed terrestrial exoplanet orbiting the star Kepler-409, located approximately 222.4 light-years (68.17 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.015% across the stellar disk), this world measures 1.199 Earth radii and has a measured mass of 6 Earth masses. Combining its mass and radius yields a mean bulk density of 19.19 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 4.17 g⊕ (40.89 m/s²), and an escape velocity of 25 km/s.

In its orbital architecture around Kepler-409, Kepler-409 b completes one full revolution every 68.958 Earth days at a semi-major axis of 0.3192 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 50.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.69, swinging from 0.099 AU at periapsis out to 0.5394 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 438 K (+165°C / +329°F) and receiving 6.15 S⊕ (~8,370 W/m²), Kepler-409 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-409 is classified as a stellar host with an effective photospheric temperature of 5,421 K, a radius of 0.897 R☉, a mass of 0.913 M☉, an estimated bolometric luminosity of 0.623 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.8 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, Kepler-409 shines at apparent V-band magnitude 9.636 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.

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