Kepler-1851 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1851 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1851, located approximately 5185.3 light-years (1589.81 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1655% across the stellar disk), this world measures 3.9 Earth radii (0.35 Jupiter radii) and has a measured mass of 14.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.35 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.95 g⊕ (9.32 m/s²), and an escape velocity of 21.6 km/s.

In its orbital architecture around Kepler-1851, Kepler-1851 b completes one full revolution every 12.023 Earth days at a semi-major axis of 0.1016 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 91.9 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 85.78 S⊕ (~116,747 W/m²), Kepler-1851 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1851 is classified as a stellar host with an effective photospheric temperature of 5,982 K, a radius of 0.879 R☉, a mass of 0.967 M☉, an estimated bolometric luminosity of 0.888 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.3 Gyr and a metallicity of [Fe/H] = -0.28 dex (metal-poor relative to the Sun). From Earth, Kepler-1851 shines at apparent V-band magnitude 15.699 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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