Kepler-1800 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1800 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1800, located approximately 1143 light-years (350.46 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0013% across the stellar disk), this world measures 0.997 Earth radii and has a measured mass of 0.961 Earth masses. Combining its mass and radius yields a mean bulk density of 5.35 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 11 km/s.

In its orbital architecture around Kepler-1800, Kepler-1800 b completes one full revolution every 4.562 Earth days at a semi-major axis of 0.05098 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 121.6 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 1533 K (+1260°C / +2300°F) and receiving 242.00 S⊕ (~329,362 W/m²), Kepler-1800 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1800 is classified as a stellar host with an effective photospheric temperature of 5,343 K, a radius of 2.506 R☉, a mass of 1.33 M☉, an estimated bolometric luminosity of 4.592 L☉. Stellar evolution modeling indicates an estimated stellar age of 11.75 Gyr and a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, Kepler-1800 shines at apparent V-band magnitude 13.194 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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