Kepler-1773 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1773 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1773, located approximately 2222 light-years (681.26 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0611% across the stellar disk), this world measures 3.505 Earth radii (0.31 Jupiter radii) and has a measured mass of 12.1 Earth masses. Combining its mass and radius yields a mean bulk density of 1.55 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.98 g⊕ (9.61 m/s²), and an escape velocity of 20.8 km/s.

In its orbital architecture around Kepler-1773, Kepler-1773 b completes one full revolution every 40.81 Earth days at a semi-major axis of 0.24831 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.2 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 623 K (+350°C / +662°F) and receiving 39.20 S⊕ (~53,351 W/m²), Kepler-1773 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1773 is classified as a stellar host with an effective photospheric temperature of 6,183 K, a radius of 1.3 R☉, a mass of 1.241 M☉, an estimated bolometric luminosity of 2.216 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.91 Gyr and a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, Kepler-1773 shines at apparent V-band magnitude 13.085 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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