Kepler-640 b

Astrophysical Synthesis & Habitability Characterization

Kepler-640 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-640, located approximately 1819.3 light-years (557.79 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0623% across the stellar disk), this world measures 2.56 Earth radii and has a measured mass of 7.08 Earth masses. Combining its mass and radius yields a mean bulk density of 2.33 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.6 km/s.

In its orbital architecture around Kepler-640, Kepler-640 b completes one full revolution every 22.248 Earth days at a semi-major axis of 0.15418 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 75.4 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 609 K (+336°C / +637°F) and receiving 35.06 S⊕ (~47,719 W/m²), Kepler-640 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-640 is classified as a stellar host with an effective photospheric temperature of 5,653 K, a radius of 0.94 R☉, a mass of 1.01 M☉, an estimated bolometric luminosity of 0.81 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.09 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, Kepler-640 shines at apparent V-band magnitude 13.885 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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