Kepler-819 b

Astrophysical Synthesis & Habitability Characterization

Kepler-819 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-819, located approximately 2166.7 light-years (664.31 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0976% across the stellar disk), this world measures 2.76 Earth radii and has a measured mass of 8.05 Earth masses. Combining its mass and radius yields a mean bulk density of 2.11 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 19.1 km/s.

In its orbital architecture around Kepler-819, Kepler-819 b completes one full revolution every 33.2 Earth days at a semi-major axis of 0.1894 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.1 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 485 K (+212°C / +414°F) and receiving 9.91 S⊕ (~13,492 W/m²), Kepler-819 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-819 is classified as a stellar host with an effective photospheric temperature of 5,279 K, a radius of 0.81 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.457 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-819 shines at apparent V-band magnitude 15.402 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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