Kepler-665 b

Astrophysical Synthesis & Habitability Characterization

Kepler-665 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-665, located approximately 1998.8 light-years (612.84 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1038% across the stellar disk), this world measures 2.6 Earth radii and has a measured mass of 7.27 Earth masses. Combining its mass and radius yields a mean bulk density of 2.28 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 18.7 km/s.

In its orbital architecture around Kepler-665, Kepler-665 b completes one full revolution every 16.013 Earth days at a semi-major axis of 0.1148 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 78 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 593 K (+320°C / +608°F) and receiving 20.72 S⊕ (~28,199 W/m²), Kepler-665 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-665 is classified as a stellar host with an effective photospheric temperature of 4,913 K, a radius of 0.74 R☉, a mass of 0.79 M☉, an estimated bolometric luminosity of 0.286 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.68 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-665 shines at apparent V-band magnitude 15.612 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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