WASP-177 b

Astrophysical Synthesis & Habitability Characterization

WASP-177 b is a confirmed gas giant exoplanet orbiting the star WASP-177, located approximately 576.7 light-years (176.82 parsecs) from the Solar System. First announced in 2019 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 3.3658% across the stellar disk), this world measures 17.71 Earth radii (1.58 Jupiter radii) and has a measured mass of 161.458 Earth masses (0.51 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.16 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.51 g⊕ (5 m/s²), and an escape velocity of 33.8 km/s.

In its orbital architecture around WASP-177, WASP-177 b completes one full revolution every 3.072 Earth days at a semi-major axis of 0.03957 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 140.1 km/s (compared to Earth's 29.8 km/s).

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1142 K (+869°C / +1596°F) and receiving 279.77 S⊕ (~380,772 W/m²), WASP-177 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-177 is classified as an orange K-type star of spectral type K2 with an effective photospheric temperature of 5,017 K, a radius of 0.885 R☉, a mass of 0.876 M☉, an estimated bolometric luminosity of 0.445 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.7 Gyr and a metallicity of [Fe/H] = 0.25 dex (metal-rich relative to the Sun). From Earth, WASP-177 shines at apparent V-band magnitude 12.312 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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