WASP-157 b
Astrophysical Synthesis & Habitability Characterization
WASP-157 b is a confirmed gas giant exoplanet orbiting the star WASP-157, located approximately 1089.5 light-years (334.04 parsecs) from the Solar System. First announced in 2016 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 0.8698% across the stellar disk), this world measures 11.19 Earth radii (1 Jupiter radii) and has a measured mass of 182.434 Earth masses (0.57 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.72 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.46 g⊕ (14.32 m/s²), and an escape velocity of 45.2 km/s.
In its orbital architecture around WASP-157, WASP-157 b completes one full revolution every 3.952 Earth days at a semi-major axis of 0.0499 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 137.4 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 1193 K (+920°C / +1688°F) and receiving 482.10 S⊕ (~656,139 W/m²), WASP-157 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-157 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,772 K, a radius of 1.1 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.205 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.6 Gyr and a metallicity of [Fe/H] = 0.25 dex (metal-rich relative to the Sun). From Earth, WASP-157 shines at apparent V-band magnitude 12.397 (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-157 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,772 K |
| Stellar Radius | 1.1000 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.205 L☉ |
| Metallicity [Fe/H] | 0.250 dex |
| Stellar Age | 1.600 Gyr |
| Apparent Magnitude | V: 12.397 · G: 12.182 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049900 AU |
| Orbital Period | 3.952 days |
| Mean Orbital Velocity | 137.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.0904° |
| Mean Bulk Density | 0.72 g/cm³ (45.2 km/s vesc) |
| Insolation Flux | 482.1005 S⊕ (~656,139 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1089.500 LY (334.037 pc) |