Kepler-40 b

Astrophysical Synthesis & Habitability Characterization

Kepler-40 b is a confirmed gas giant exoplanet orbiting the star Kepler-40, located approximately 7517.9 light-years (2305.01 parsecs) from the Solar System. First announced in 2010 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.3184% across the stellar disk), this world measures 13.11 Earth radii (1.17 Jupiter radii) and has a measured mass of 699.2 Earth masses (2.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.71 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.07 g⊕ (39.91 m/s²), and an escape velocity of 81.7 km/s.

In its orbital architecture around Kepler-40, Kepler-40 b completes one full revolution every 6.873 Earth days at a semi-major axis of 0.08 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 126.6 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 1620 K (+1347°C / +2457°F) and receiving 1,187.97 S⊕ (~1,616,820 W/m²), Kepler-40 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-40 is classified as a warm F-type star of spectral type F5 IV with an effective photospheric temperature of 6,510 K, a radius of 2.13 R☉, a mass of 1.48 M☉, an estimated bolometric luminosity of 7.311 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.8 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, Kepler-40 shines at apparent V-band magnitude 14.657 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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