Kepler-1664 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1664 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1664, located approximately 2044 light-years (626.69 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0673% across the stellar disk), this world measures 3.033 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.45 Earth masses. Combining its mass and radius yields a mean bulk density of 1.87 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 19.7 km/s.

In its orbital architecture around Kepler-1664, Kepler-1664 b completes one full revolution every 14.387 Earth days at a semi-major axis of 0.1137 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 86 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 776 K (+503°C / +937°F) and receiving 85.46 S⊕ (~116,311 W/m²), Kepler-1664 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1664 is classified as a stellar host with an effective photospheric temperature of 5,736 K, a radius of 1.072 R☉, a mass of 0.944 M☉, an estimated bolometric luminosity of 1.116 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.2 Gyr and a metallicity of [Fe/H] = 0.37 dex (metal-rich relative to the Sun). From Earth, Kepler-1664 shines at apparent V-band magnitude 13.621 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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