Kepler-1151 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1151 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1151, located approximately 2225.8 light-years (682.44 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0573% across the stellar disk), this world measures 2.22 Earth radii and has a measured mass of 5.56 Earth masses. Combining its mass and radius yields a mean bulk density of 2.8 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.7 km/s.

In its orbital architecture around Kepler-1151, Kepler-1151 b completes one full revolution every 65.648 Earth days at a semi-major axis of 0.3197 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 53 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 4.86 S⊕ (~6,614 W/m²), Kepler-1151 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1151 is classified as a stellar host with an effective photospheric temperature of 5,470 K, a radius of 0.85 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.58 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.37 Gyr and a metallicity of [Fe/H] = -0.11 dex (metal-poor relative to the Sun). From Earth, Kepler-1151 shines at apparent V-band magnitude 15.005 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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