WASP-189 b
Astrophysical Synthesis & Habitability Characterization
WASP-189 b is a confirmed gas giant exoplanet orbiting the star WASP-189, located approximately 325.3 light-years (99.73 parsecs) from the Solar System. First announced in 2020 by CHaracterising ExOPlanets Satellite (CHEOPS) using the Transit detection technique (producing an estimated primary transit depth of 0.497% across the stellar disk), this world measures 18.147 Earth radii (1.62 Jupiter radii) and has a measured mass of 632.479 Earth masses (1.99 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.58 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.92 g⊕ (18.83 m/s²), and an escape velocity of 66 km/s.
In its orbital architecture around WASP-189, WASP-189 b completes one full revolution every 2.724 Earth days at a semi-major axis of 0.05053 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 201.8 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 3353 K (+3080°C / +5576°F) and receiving 8,083.72 S⊕ (~11,001,939 W/m²), WASP-189 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-189 is classified as a stellar host with an effective photospheric temperature of 8,000 K, a radius of 2.36 R☉, a mass of 2.03 M☉, an estimated bolometric luminosity of 20.468 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.73 Gyr and a metallicity of [Fe/H] = 0.29 dex (metal-rich relative to the Sun). From Earth, WASP-189 shines at apparent V-band magnitude 6.598 (accessible to binoculars and small amateur telescopes) 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: CHaracterising ExOPlanets Satellite (CHEOPS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | WASP-189 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 8,000 K |
| Stellar Radius | 2.3600 R☉ |
| Stellar Mass | 2.0300 M☉ |
| Bolometric Luminosity | 20.468 L☉ |
| Metallicity [Fe/H] | 0.290 dex |
| Stellar Age | 0.730 Gyr |
| Apparent Magnitude | V: 6.598 · G: 6.554 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050530 AU |
| Orbital Period | 2.724 days |
| Mean Orbital Velocity | 201.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 84.0300° |
| Mean Bulk Density | 0.58 g/cm³ (66 km/s vesc) |
| Insolation Flux | 8083.7169 S⊕ (~11,001,939 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 325.300 LY (99.731 pc) |