Kepler-1213 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1213 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1213, located approximately 2634.7 light-years (807.81 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0081% across the stellar disk), this world measures 1.19 Earth radii and has a measured mass of 1.81 Earth masses. Combining its mass and radius yields a mean bulk density of 5.92 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.28 g⊕ (12.55 m/s²), and an escape velocity of 13.8 km/s.

In its orbital architecture around Kepler-1213, Kepler-1213 b completes one full revolution every 5.35 Earth days at a semi-major axis of 0.06026 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 122.5 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 1156 K (+883°C / +1621°F) and receiving 595.42 S⊕ (~810,372 W/m²), Kepler-1213 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1213 is classified as a stellar host with an effective photospheric temperature of 6,050 K, a radius of 1.21 R☉, a mass of 1.14 M☉, an estimated bolometric luminosity of 1.76 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.47 Gyr and a metallicity of [Fe/H] = 0.13 dex (metal-rich relative to the Sun). From Earth, Kepler-1213 shines at apparent V-band magnitude 13.416 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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