Kepler-798 b

Astrophysical Synthesis & Habitability Characterization

Kepler-798 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-798, located approximately 3171.1 light-years (972.27 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0289% across the stellar disk), this world measures 2.39 Earth radii and has a measured mass of 6.3 Earth masses. Combining its mass and radius yields a mean bulk density of 2.54 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.

In its orbital architecture around Kepler-798, Kepler-798 b completes one full revolution every 13.719 Earth days at a semi-major axis of 0.1174 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 93.1 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 864 K (+591°C / +1096°F) and receiving 141.89 S⊕ (~193,110 W/m²), Kepler-798 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-798 is classified as a stellar host with an effective photospheric temperature of 6,224 K, a radius of 1.29 R☉, a mass of 1.19 M☉, an estimated bolometric luminosity of 2.241 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.82 Gyr and a metallicity of [Fe/H] = 0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-798 shines at apparent V-band magnitude 14.221 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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