Kepler-971 b

Astrophysical Synthesis & Habitability Characterization

Kepler-971 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-971, located approximately 1104.1 light-years (338.52 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0528% across the stellar disk), this world measures 2.13 Earth radii and has a measured mass of 5.18 Earth masses. Combining its mass and radius yields a mean bulk density of 2.96 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-971, Kepler-971 b completes one full revolution every 9.591 Earth days at a semi-major axis of 0.08679 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 98.4 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 1087 K (+814°C / +1497°F) and receiving 82.77 S⊕ (~112,645 W/m²), Kepler-971 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-971 is classified as a stellar host with an effective photospheric temperature of 5,431 K, a radius of 0.85 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.564 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.47 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-971 shines at apparent V-band magnitude 13.483 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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