WASP-173 A b
Astrophysical Synthesis & Habitability Characterization
WASP-173 A b is a confirmed gas giant exoplanet orbiting the star WASP-173 A, located approximately 759.9 light-years (232.98 parsecs) from the Solar System. First announced in 2018 by SuperWASP-South using the Transit detection technique (producing an estimated primary transit depth of 1.2343% across the stellar disk), this world measures 13.451 Earth radii (1.2 Jupiter radii) and has a measured mass of 1172.793 Earth masses (3.69 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.66 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.48 g⊕ (63.55 m/s²), and an escape velocity of 104.4 km/s.
In its orbital architecture around WASP-173 A, WASP-173 A b completes one full revolution every 1.387 Earth days at a semi-major axis of 0.0248 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 194.6 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 1880 K (+1607°C / +2925°F) and receiving 1,920.00 S⊕ (~2,613,120 W/m²), WASP-173 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-173 A is classified as a solar-type yellow star of spectral type G3 with an effective photospheric temperature of 5,800 K, a radius of 1.11 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.251 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.78 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, WASP-173 A shines at apparent V-band magnitude 11.15 (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-South · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | WASP-173 A |
| Spectral Type | G3 |
| Effective Temp (Teff) | 5,800 K |
| Stellar Radius | 1.1100 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.251 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 6.780 Gyr |
| Apparent Magnitude | V: 11.150 · G: 11.398 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.024800 AU |
| Orbital Period | 1.387 days |
| Mean Orbital Velocity | 194.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.2000° |
| Mean Bulk Density | 2.66 g/cm³ (104.4 km/s vesc) |
| Insolation Flux | 1920.0000 S⊕ (~2,613,120 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 759.900 LY (232.980 pc) |