WASP-120 b
Astrophysical Synthesis & Habitability Characterization
WASP-120 b is a confirmed gas giant exoplanet orbiting the star WASP-120, located approximately 1243.2 light-years (381.17 parsecs) from the Solar System. First announced in 2016 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 0.7191% across the stellar disk), this world measures 15.58 Earth radii (1.39 Jupiter radii) and has a measured mass of 1541.476 Earth masses (4.85 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.25 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.35 g⊕ (62.27 m/s²), and an escape velocity of 111.3 km/s.
In its orbital architecture around WASP-120, WASP-120 b completes one full revolution every 3.611 Earth days at a semi-major axis of 0.0514 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 154.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.057 carries the world between 0.0485 AU at periapsis and 0.0543 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1749 K (+1476°C / +2689°F) and receiving 1,818.55 S⊕ (~2,475,045 W/m²), WASP-120 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-120 is classified as a warm F-type star of spectral type F5 with an effective photospheric temperature of 6,450 K, a radius of 1.6844 R☉, a mass of 1.393 M☉, an estimated bolometric luminosity of 4.406 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.7 Gyr and a metallicity of [Fe/H] = -0.05 dex (near-solar heavy-element abundance). From Earth, WASP-120 shines at apparent V-band magnitude 10.96 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.
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-120 |
| Spectral Type | F5 |
| Effective Temp (Teff) | 6,450 K |
| Stellar Radius | 1.6844 R☉ |
| Stellar Mass | 1.3930 M☉ |
| Bolometric Luminosity | 4.406 L☉ |
| Metallicity [Fe/H] | -0.050 dex |
| Stellar Age | 0.700 Gyr |
| Apparent Magnitude | V: 10.960 · G: 10.899 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.051400 AU |
| Orbital Period | 3.611 days |
| Mean Orbital Velocity | 154.8 km/s |
| Orbital Eccentricity (e) | 0.05700 |
| Orbital Inclination (i) | 84.5400° |
| Mean Bulk Density | 2.25 g/cm³ (111.3 km/s vesc) |
| Insolation Flux | 1818.5489 S⊕ (~2,475,045 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1243.200 LY (381.174 pc) |