Kepler-1733 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1733 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1733, located approximately 6785.7 light-years (2080.51 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0709% across the stellar disk), this world measures 3.636 Earth radii (0.32 Jupiter radii) and has a measured mass of 12.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.47 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 21 km/s.

In its orbital architecture around Kepler-1733, Kepler-1733 b completes one full revolution every 9.23 Earth days at a semi-major axis of 0.0933 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 110 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 1021 K (+748°C / +1378°F) and receiving 257.11 S⊕ (~349,927 W/m²), Kepler-1733 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1733 is classified as a stellar host with an effective photospheric temperature of 6,320 K, a radius of 1.252 R☉, a mass of 1.273 M☉, an estimated bolometric luminosity of 2.244 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.2 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, Kepler-1733 shines at apparent V-band magnitude 15.612 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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