Kepler-1333 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1333 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1333, located approximately 3041.2 light-years (932.45 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0784% across the stellar disk), this world measures 2.81 Earth radii and has a measured mass of 8.3 Earth masses. Combining its mass and radius yields a mean bulk density of 2.06 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.

In its orbital architecture around Kepler-1333, Kepler-1333 b completes one full revolution every 109.647 Earth days at a semi-major axis of 0.4382 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 43.5 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 428 K (+155°C / +311°F) and receiving 3.30 S⊕ (~4,489 W/m²), Kepler-1333 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1333 is classified as a stellar host with an effective photospheric temperature of 5,628 K, a radius of 0.92 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.762 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.57 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-1333 shines at apparent V-band magnitude 15.421 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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