Kepler-1778 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1778 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1778, located approximately 4162.7 light-years (1276.29 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0638% across the stellar disk), this world measures 3.017 Earth radii (0.27 Jupiter radii) and has a measured mass of 9.36 Earth masses. Combining its mass and radius yields a mean bulk density of 1.88 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-1778, Kepler-1778 b completes one full revolution every 10.087 Earth days at a semi-major axis of 0.0956 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 103.1 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 942 K (+669°C / +1236°F) and receiving 186.14 S⊕ (~253,337 W/m²), Kepler-1778 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1778 is classified as a stellar host with an effective photospheric temperature of 6,310 K, a radius of 1.095 R☉, a mass of 1.143 M☉, an estimated bolometric luminosity of 1.705 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.3 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-1778 shines at apparent V-band magnitude 15.273 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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