Kepler-838 b

Astrophysical Synthesis & Habitability Characterization

Kepler-838 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-838, located approximately 3600.9 light-years (1104.04 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.068% across the stellar disk), this world measures 2.73 Earth radii and has a measured mass of 7.9 Earth masses. Combining its mass and radius yields a mean bulk density of 2.14 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-838, Kepler-838 b completes one full revolution every 15.75 Earth days at a semi-major axis of 0.1266 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.4 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 777 K (+504°C / +939°F) and receiving 61.09 S⊕ (~83,142 W/m²), Kepler-838 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-838 is classified as a stellar host with an effective photospheric temperature of 5,770 K, a radius of 0.96 R☉, a mass of 0.98 M☉, an estimated bolometric luminosity of 0.917 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.17 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-838 shines at apparent V-band magnitude 15.424 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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