WASP-118 b

Astrophysical Synthesis & Habitability Characterization

WASP-118 b is a confirmed gas giant exoplanet orbiting the star WASP-118, located approximately 1228.5 light-years (376.66 parsecs) from the Solar System. First announced in 2016 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 0.7613% across the stellar disk), this world measures 16.141 Earth radii (1.44 Jupiter radii) and has a measured mass of 163.365 Earth masses (0.51 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.21 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.63 g⊕ (6.18 m/s²), and an escape velocity of 35.6 km/s.

In its orbital architecture around WASP-118, WASP-118 b completes one full revolution every 4.046 Earth days at a semi-major axis of 0.05453 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 146.6 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 1729 K (+1456°C / +2653°F) and receiving 6,586.47 S⊕ (~8,964,186 W/m²), WASP-118 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-118 is classified as a warm F-type star of spectral type F6 with an effective photospheric temperature of 6,410 K, a radius of 1.696 R☉, a mass of 1.32 M☉, an estimated bolometric luminosity of 4.357 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.17 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, WASP-118 shines at apparent V-band magnitude 11.009 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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