Kepler-789 b

Astrophysical Synthesis & Habitability Characterization

Kepler-789 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-789, located approximately 4827.6 light-years (1480.16 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0363% across the stellar disk), this world measures 2.12 Earth radii and has a measured mass of 5.14 Earth masses. Combining its mass and radius yields a mean bulk density of 2.97 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.4 km/s.

In its orbital architecture around Kepler-789, Kepler-789 b completes one full revolution every 8.638 Earth days at a semi-major axis of 0.0951 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 119.8 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 1419 K (+1146°C / +2095°F) and receiving 312.34 S⊕ (~425,095 W/m²), Kepler-789 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-789 is classified as a stellar host with an effective photospheric temperature of 5,870 K, a radius of 1.02 R☉, a mass of 1.01 M☉, an estimated bolometric luminosity of 1.108 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.72 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-789 shines at apparent V-band magnitude 14.723 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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