Kepler-957 b

Astrophysical Synthesis & Habitability Characterization

Kepler-957 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-957, located approximately 2689.8 light-years (824.69 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.452% across the stellar disk), this world measures 5.5 Earth radii (0.49 Jupiter radii) and has a measured mass of 25.9 Earth masses. Combining its mass and radius yields a mean bulk density of 0.86 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.86 g⊕ (8.43 m/s²), and an escape velocity of 24.3 km/s.

In its orbital architecture around Kepler-957, Kepler-957 b completes one full revolution every 5.907 Earth days at a semi-major axis of 0.0559 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 102.9 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 769 K (+496°C / +925°F) and receiving 124.91 S⊕ (~170,004 W/m²), Kepler-957 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-957 is classified as a stellar host with an effective photospheric temperature of 4,963 K, a radius of 0.75 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.306 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.75 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-957 shines at apparent V-band magnitude 15.833 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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