WASP-89 b
Astrophysical Synthesis & Habitability Characterization
WASP-89 b is a confirmed gas giant exoplanet orbiting the star WASP-89, located approximately 948.9 light-years (290.95 parsecs) from the Solar System. First announced in 2015 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.4749% across the stellar disk), this world measures 11.657 Earth radii (1.04 Jupiter radii) and has a measured mass of 1875.197 Earth masses (5.9 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.53 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 13.8 g⊕ (135.33 m/s²), and an escape velocity of 141.9 km/s.
In its orbital architecture around WASP-89, WASP-89 b completes one full revolution every 3.356 Earth days at a semi-major axis of 0.0427 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 138.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.193 carries the world between 0.0345 AU at periapsis and 0.0509 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1120 K (+847°C / +1557°F) and receiving 278.85 S⊕ (~379,519 W/m²), WASP-89 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-89 is classified as an orange K-type star of spectral type K3 with an effective photospheric temperature of 5,130 K, a radius of 0.88 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.481 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.3 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, WASP-89 shines at apparent V-band magnitude 13.21 (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-89 |
| Spectral Type | K3 |
| Effective Temp (Teff) | 5,130 K |
| Stellar Radius | 0.8800 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 0.481 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 1.300 Gyr |
| Apparent Magnitude | V: 13.210 · G: 12.989 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.042700 AU |
| Orbital Period | 3.356 days |
| Mean Orbital Velocity | 138.4 km/s |
| Orbital Eccentricity (e) | 0.19300 |
| Orbital Inclination (i) | 89.4000° |
| Mean Bulk Density | 6.53 g/cm³ (141.9 km/s vesc) |
| Insolation Flux | 278.8533 S⊕ (~379,519 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 948.900 LY (290.946 pc) |