WASP-156 b
Astrophysical Synthesis & Habitability Characterization
WASP-156 b is a confirmed gas giant exoplanet orbiting the star WASP-156, located approximately 398.1 light-years (122.07 parsecs) from the Solar System. First announced in 2017 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 0.465% across the stellar disk), this world measures 6.15 Earth radii (0.55 Jupiter radii) and has a measured mass of 42 Earth masses (0.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 29.2 km/s.
In its orbital architecture around WASP-156, WASP-156 b completes one full revolution every 3.836 Earth days at a semi-major axis of 0.046 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 130.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.16 carries the world between 0.0386 AU at periapsis and 0.0534 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 935 K (+662°C / +1224°F) and receiving 150.00 S⊕ (~204,150 W/m²), WASP-156 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-156 is classified as an orange K-type star of spectral type K3 V with an effective photospheric temperature of 5,036 K, a radius of 0.8268 R☉, a mass of 0.8712 M☉, an estimated bolometric luminosity of 0.394 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.6 Gyr and a metallicity of [Fe/H] = 0.32 dex (metal-rich relative to the Sun). From Earth, WASP-156 shines at apparent V-band magnitude 11.559 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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-156 |
| Spectral Type | K3 V |
| Effective Temp (Teff) | 5,036 K |
| Stellar Radius | 0.8268 R☉ |
| Stellar Mass | 0.8712 M☉ |
| Bolometric Luminosity | 0.394 L☉ |
| Metallicity [Fe/H] | 0.320 dex |
| Stellar Age | 5.600 Gyr |
| Apparent Magnitude | V: 11.559 · G: 11.323 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.046000 AU |
| Orbital Period | 3.836 days |
| Mean Orbital Velocity | 130.5 km/s |
| Orbital Eccentricity (e) | 0.16000 |
| Orbital Inclination (i) | 88.1000° |
| Mean Bulk Density | 1 g/cm³ (29.2 km/s vesc) |
| Insolation Flux | 150.0000 S⊕ (~204,150 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 398.100 LY (122.066 pc) |