Kepler-12 b

Astrophysical Synthesis & Habitability Characterization

Kepler-12 b is a confirmed gas giant exoplanet orbiting the star Kepler-12, located approximately 2874.7 light-years (881.39 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 1.4773% across the stellar disk), this world measures 19.661 Earth radii (1.75 Jupiter radii) and has a measured mass of 137.303 Earth masses (0.43 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.1 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.36 g⊕ (3.53 m/s²), and an escape velocity of 29.6 km/s.

In its orbital architecture around Kepler-12, Kepler-12 b completes one full revolution every 4.438 Earth days at a semi-major axis of 0.0553 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 135.6 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 1480 K (+1207°C / +2205°F) and receiving 877.54 S⊕ (~1,194,331 W/m²), Kepler-12 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-12 is classified as a stellar host with an effective photospheric temperature of 5,947 K, a radius of 1.483 R☉, a mass of 1.166 M☉, an estimated bolometric luminosity of 2.468 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, Kepler-12 shines at apparent V-band magnitude 13.468 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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