Kepler-489 b

Astrophysical Synthesis & Habitability Characterization

Kepler-489 b is a confirmed gas giant exoplanet orbiting the star Kepler-489, located approximately 1205.6 light-years (369.65 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.8673% across the stellar disk), this world measures 7.72 Earth radii (0.69 Jupiter radii) and has a measured mass of 46.1 Earth masses (0.15 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.55 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.77 g⊕ (7.55 m/s²), and an escape velocity of 27.3 km/s.

In its orbital architecture around Kepler-489, Kepler-489 b completes one full revolution every 17.276 Earth days at a semi-major axis of 0.12109 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 76.3 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 538 K (+265°C / +509°F) and receiving 20.62 S⊕ (~28,061 W/m²), Kepler-489 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-489 is classified as a stellar host with an effective photospheric temperature of 5,014 K, a radius of 0.76 R☉, a mass of 0.82 M☉, an estimated bolometric luminosity of 0.328 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.31 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-489 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).