Kepler-1747 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1747 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1747, located approximately 4309.8 light-years (1321.38 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2043% across the stellar disk), this world measures 4.265 Earth radii (0.38 Jupiter radii) and has a measured mass of 16.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.19 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.92 g⊕ (9.02 m/s²), and an escape velocity of 22.2 km/s.

In its orbital architecture around Kepler-1747, Kepler-1747 b completes one full revolution every 6.23 Earth days at a semi-major axis of 0.066 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 115.2 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 875 K (+602°C / +1116°F) and receiving 138.33 S⊕ (~188,267 W/m²), Kepler-1747 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1747 is classified as a stellar host with an effective photospheric temperature of 5,477 K, a radius of 0.865 R☉, a mass of 0.983 M☉, an estimated bolometric luminosity of 0.604 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.7 Gyr and a metallicity of [Fe/H] = 0.21 dex (metal-rich relative to the Sun). From Earth, Kepler-1747 shines at apparent V-band magnitude 16.197 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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