Kepler-1009 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1009 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1009, located approximately 1157.9 light-years (355.02 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1218% across the stellar disk), this world measures 2.17 Earth radii and has a measured mass of 5.35 Earth masses. Combining its mass and radius yields a mean bulk density of 2.89 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 17.6 km/s.

In its orbital architecture around Kepler-1009, Kepler-1009 b completes one full revolution every 11.35 Earth days at a semi-major axis of 0.0796 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 403 K (+130°C / +266°F) and receiving 11.56 S⊕ (~15,735 W/m²), Kepler-1009 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1009 is classified as a stellar host with an effective photospheric temperature of 4,027 K, a radius of 0.57 R☉, a mass of 0.59 M☉, an estimated bolometric luminosity of 0.077 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.16 Gyr and a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, Kepler-1009 shines at apparent V-band magnitude 15.758 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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