WASP-17 b

Astrophysical Synthesis & Habitability Characterization

WASP-17 b is a confirmed gas giant exoplanet orbiting the star WASP-17, located approximately 1323.9 light-years (405.91 parsecs) from the Solar System. First announced in 2009 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.6634% across the stellar disk), this world measures 20.961 Earth radii (1.87 Jupiter radii) and has a measured mass of 247.907 Earth masses (0.78 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 0.56 g⊕ (5.49 m/s²), and an escape velocity of 38.5 km/s.

In its orbital architecture around WASP-17, WASP-17 b completes one full revolution every 3.735 Earth days at a semi-major axis of 0.0515 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 150 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 1755 K (+1482°C / +2700°F) and receiving 1,292.19 S⊕ (~1,758,671 W/m²), WASP-17 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-17 is classified as a warm F-type star of spectral type F4 with an effective photospheric temperature of 6,550 K, a radius of 1.49 R☉, a mass of 2.28 M☉, an estimated bolometric luminosity of 3.666 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.65 Gyr and a metallicity of [Fe/H] = -0.25 dex (metal-poor relative to the Sun). From Earth, WASP-17 shines at apparent V-band magnitude 11.588 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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