WASP-139 b

Astrophysical Synthesis & Habitability Characterization

WASP-139 b is a confirmed gas giant exoplanet orbiting the star WASP-139, located approximately 693 light-years (212.47 parsecs) from the Solar System. First announced in 2016 by SuperWASP-South using the Transit detection technique (producing an estimated primary transit depth of 1.056% across the stellar disk), this world measures 8.967 Earth radii (0.8 Jupiter radii) and has a measured mass of 37.186 Earth masses (0.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.46 g⊕ (4.51 m/s²), and an escape velocity of 22.8 km/s.

In its orbital architecture around WASP-139, WASP-139 b completes one full revolution every 5.924 Earth days at a semi-major axis of 0.062 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 113.9 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 910 K (+637°C / +1179°F) and receiving 120.71 S⊕ (~164,283 W/m²), WASP-139 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-139 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 5,310 K, a radius of 0.8 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.457 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.5 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, WASP-139 shines at apparent V-band magnitude 12.456 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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