Kepler-1677 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1677 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1677, located approximately 2398.5 light-years (735.37 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0393% across the stellar disk), this world measures 2.702 Earth radii and has a measured mass of 7.76 Earth masses. Combining its mass and radius yields a mean bulk density of 2.17 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19 km/s.

In its orbital architecture around Kepler-1677, Kepler-1677 b completes one full revolution every 22.064 Earth days at a semi-major axis of 0.1599 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 78.8 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 712 K (+439°C / +822°F) and receiving 59.40 S⊕ (~80,843 W/m²), Kepler-1677 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1677 is classified as a stellar host with an effective photospheric temperature of 6,014 K, a radius of 1.2496 R☉, a mass of 1.11 M☉, an estimated bolometric luminosity of 1.833 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.29 Gyr and a metallicity of [Fe/H] = 0.108 dex (metal-rich relative to the Sun). From Earth, Kepler-1677 shines at apparent V-band magnitude 13.806 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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