Kepler-533 b

Astrophysical Synthesis & Habitability Characterization

Kepler-533 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-533, located approximately 988.1 light-years (302.96 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1852% across the stellar disk), this world measures 3.38 Earth radii (0.3 Jupiter radii) and has a measured mass of 11.4 Earth masses. Combining its mass and radius yields a mean bulk density of 1.63 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 20.5 km/s.

In its orbital architecture around Kepler-533, Kepler-533 b completes one full revolution every 28.511 Earth days at a semi-major axis of 0.16704 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 63.7 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 423 K (+150°C / +302°F) and receiving 8.77 S⊕ (~11,935 W/m²), Kepler-533 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-533 is classified as a stellar host with an effective photospheric temperature of 4,758 K, a radius of 0.72 R☉, a mass of 0.78 M☉, an estimated bolometric luminosity of 0.238 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.24 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-533 shines at apparent V-band magnitude 14.128 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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