Kepler-642 b

Astrophysical Synthesis & Habitability Characterization

Kepler-642 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-642, located approximately 2549.2 light-years (781.58 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0257% across the stellar disk), this world measures 2.9 Earth radii and has a measured mass of 8.75 Earth masses. Combining its mass and radius yields a mean bulk density of 1.98 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.4 km/s.

In its orbital architecture around Kepler-642, Kepler-642 b completes one full revolution every 4.417 Earth days at a semi-major axis of 0.05631 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 138.7 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 1810 K (+1537°C / +2799°F) and receiving 719.37 S⊕ (~979,067 W/m²), Kepler-642 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-642 is classified as a stellar host with an effective photospheric temperature of 6,570 K, a radius of 1.66 R☉, a mass of 1.4 M☉, an estimated bolometric luminosity of 4.606 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.95 Gyr and a metallicity of [Fe/H] = 0.06 dex (metal-rich relative to the Sun). From Earth, Kepler-642 shines at apparent V-band magnitude 13.335 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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