Kepler-676 b

Astrophysical Synthesis & Habitability Characterization

Kepler-676 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-676, located approximately 962.8 light-years (295.2 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.3235% across the stellar disk), this world measures 3.04 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.48 Earth masses. Combining its mass and radius yields a mean bulk density of 1.86 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.8 km/s.

In its orbital architecture around Kepler-676, Kepler-676 b completes one full revolution every 11.598 Earth days at a semi-major axis of 0.0798 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 74.9 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 396 K (+123°C / +253°F) and receiving 8.24 S⊕ (~11,216 W/m²), Kepler-676 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-676 is classified as a stellar host with an effective photospheric temperature of 3,701 K, a radius of 0.49 R☉, a mass of 0.51 M☉, an estimated bolometric luminosity of 0.04 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.27 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-676 shines at apparent V-band magnitude 17.15 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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