Kepler-1808 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1808 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1808, located approximately 3333.3 light-years (1022.01 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0967% across the stellar disk), this world measures 3.025 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.4 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-1808, Kepler-1808 b completes one full revolution every 23.34 Earth days at a semi-major axis of 0.1467 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 68.4 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 601 K (+328°C / +622°F) and receiving 30.94 S⊕ (~42,109 W/m²), Kepler-1808 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1808 is classified as a stellar host with an effective photospheric temperature of 5,530 K, a radius of 0.892 R☉, a mass of 0.773 M☉, an estimated bolometric luminosity of 0.668 L☉. Stellar evolution modeling indicates an estimated stellar age of 12.1 Gyr and a metallicity of [Fe/H] = -0.34 dex (metal-poor relative to the Sun). From Earth, Kepler-1808 shines at apparent V-band magnitude 15.424 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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