WASP-8 b
Astrophysical Synthesis & Habitability Characterization
WASP-8 b is a confirmed gas giant exoplanet orbiting the star WASP-8, located approximately 293.4 light-years (89.96 parsecs) from the Solar System. First announced in 2010 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.271% across the stellar disk), this world measures 12.666 Earth radii (1.13 Jupiter radii) and has a measured mass of 807.288 Earth masses (2.54 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.19 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.03 g⊕ (49.33 m/s²), and an escape velocity of 89.3 km/s.
In its orbital architecture around WASP-8, WASP-8 b completes one full revolution every 8.159 Earth days at a semi-major axis of 0.0801 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 106.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.31, swinging from 0.0553 AU at periapsis out to 0.1049 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1059 K (+786°C / +1447°F) and receiving 209.12 S⊕ (~284,610 W/m²), WASP-8 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-8 is classified as a solar-type yellow star of spectral type G8 V with an effective photospheric temperature of 5,600 K, a radius of 1.03 R☉, a mass of 1.34 M☉, an estimated bolometric luminosity of 0.936 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.17 dex (metal-rich relative to the Sun). From Earth, WASP-8 shines at apparent V-band magnitude 9.789 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The WASP-8 system is a multi-planet architecture hosting 2 confirmed worlds, with WASP-8 b sharing its stellar neighborhood alongside WASP-8 c.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: SuperWASP · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | WASP-8 |
| Spectral Type | G8 V |
| Effective Temp (Teff) | 5,600 K |
| Stellar Radius | 1.0300 R☉ |
| Stellar Mass | 1.3400 M☉ |
| Bolometric Luminosity | 0.936 L☉ |
| Metallicity [Fe/H] | 0.170 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 9.789 · G: 9.612 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.080100 AU |
| Orbital Period | 8.159 days |
| Mean Orbital Velocity | 106.8 km/s |
| Orbital Eccentricity (e) | 0.31000 |
| Orbital Inclination (i) | 88.5500° |
| Mean Bulk Density | 2.19 g/cm³ (89.3 km/s vesc) |
| Insolation Flux | 209.1180 S⊕ (~284,610 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 293.400 LY (89.961 pc) |