Kepler-686 b

Astrophysical Synthesis & Habitability Characterization

Kepler-686 b is a confirmed gas giant exoplanet orbiting the star Kepler-686, located approximately 4862.8 light-years (1490.94 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 1.4659% across the stellar disk), this world has a measured radius of 12.15 Earth radii (1.08 R♃), though radial-velocity mass constraints remain unmeasured in the current composite catalogue.

In its orbital architecture around Kepler-686, Kepler-686 b completes one full revolution every 1.595 Earth days at a semi-major axis of 0.0258 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 176 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 1539 K (+1266°C / +2311°F) and receiving 2,132.90 S⊕ (~2,902,881 W/m²), Kepler-686 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-686 is classified as a stellar host with an effective photospheric temperature of 5,649 K, a radius of 0.92 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.773 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, Kepler-686 shines at apparent V-band magnitude 16.02 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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