Kepler-671 b

Astrophysical Synthesis & Habitability Characterization

Kepler-671 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-671, located approximately 3810.4 light-years (1168.26 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0674% across the stellar disk), this world measures 2.69 Earth radii and has a measured mass of 7.7 Earth masses. Combining its mass and radius yields a mean bulk density of 2.18 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 18.9 km/s.

In its orbital architecture around Kepler-671, Kepler-671 b completes one full revolution every 4.281 Earth days at a semi-major axis of 0.0503 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 127.8 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 1012 K (+739°C / +1362°F) and receiving 331.44 S⊕ (~451,087 W/m²), Kepler-671 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-671 is classified as a stellar host with an effective photospheric temperature of 5,624 K, a radius of 0.95 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.81 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, Kepler-671 shines at apparent V-band magnitude 15.491 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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