WASP-20 b

Astrophysical Synthesis & Habitability Characterization

WASP-20 b is a confirmed gas giant exoplanet orbiting the star WASP-20, located approximately 691 light-years (211.88 parsecs) from the Solar System. First announced in 2015 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.3037% across the stellar disk), this world measures 15.468 Earth radii (1.38 Jupiter radii) and has a measured mass of 98.841 Earth masses (0.31 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.15 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.41 g⊕ (4.02 m/s²), and an escape velocity of 28.3 km/s.

In its orbital architecture around WASP-20, WASP-20 b completes one full revolution every 4.9 Earth days at a semi-major axis of 0.05999 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 133.2 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 1362 K (+1089°C / +1992°F) and receiving 259.86 S⊕ (~353,675 W/m²), WASP-20 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-20 is classified as a warm F-type star of spectral type F9 with an effective photospheric temperature of 5,940 K, a radius of 1.242 R☉, a mass of 1.2 M☉, an estimated bolometric luminosity of 1.723 L☉. Stellar evolution modeling indicates an estimated stellar age of 7 Gyr and a metallicity of [Fe/H] = -0.008 dex (near-solar heavy-element abundance). From Earth, WASP-20 shines at apparent V-band magnitude 10.675 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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