Kepler-1771 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1771 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1771, located approximately 1845.2 light-years (565.75 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1584% across the stellar disk), this world measures 4.055 Earth radii (0.36 Jupiter radii) and has a measured mass of 15.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.94 g⊕ (9.22 m/s²), and an escape velocity of 21.9 km/s.

In its orbital architecture around Kepler-1771, Kepler-1771 b completes one full revolution every 88.644 Earth days at a semi-major axis of 0.3815 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 46.8 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 391 K (+118°C / +244°F) and receiving 5.51 S⊕ (~7,499 W/m²), Kepler-1771 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1771 is classified as a stellar host with an effective photospheric temperature of 5,661 K, a radius of 0.934 R☉, a mass of 0.941 M☉, an estimated bolometric luminosity of 0.804 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.8 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-1771 shines at apparent V-band magnitude 13.802 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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