WASP-166 b

Astrophysical Synthesis & Habitability Characterization

WASP-166 b is a confirmed gas giant exoplanet orbiting the star WASP-166, located approximately 372.4 light-years (114.17 parsecs) from the Solar System. First announced in 2019 by WASP-South using the Transit detection technique (producing an estimated primary transit depth of 0.2816% across the stellar disk), this world measures 7.062 Earth radii (0.63 Jupiter radii) and has a measured mass of 32.101 Earth masses (0.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.5 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.64 g⊕ (6.28 m/s²), and an escape velocity of 23.8 km/s.

In its orbital architecture around WASP-166, WASP-166 b completes one full revolution every 5.444 Earth days at a semi-major axis of 0.0641 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 128.1 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 1270 K (+997°C / +1827°F) and receiving 440.00 S⊕ (~598,840 W/m²), WASP-166 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-166 is classified as a warm F-type star of spectral type F9 V with an effective photospheric temperature of 6,050 K, a radius of 1.22 R☉, a mass of 1.19 M☉, an estimated bolometric luminosity of 1.789 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.1 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, WASP-166 shines at apparent V-band magnitude 9.351 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere.

Discovery Facility: WASP-South · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).