WASP-28 b
Astrophysical Synthesis & Habitability Characterization
WASP-28 b is a confirmed gas giant exoplanet orbiting the star WASP-28, located approximately 1136.6 light-years (348.49 parsecs) from the Solar System. First announced in 2014 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.338% across the stellar disk), this world measures 13.664 Earth radii (1.22 Jupiter radii) and has a measured mass of 282.549 Earth masses (0.89 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.61 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.51 g⊕ (14.81 m/s²), and an escape velocity of 50.9 km/s.
In its orbital architecture around WASP-28, WASP-28 b completes one full revolution every 3.409 Earth days at a semi-major axis of 0.0442 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 141.1 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 1456 K (+1183°C / +2161°F) and receiving 695.65 S⊕ (~946,780 W/m²), WASP-28 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-28 is classified as a warm F-type star of spectral type F8 with an effective photospheric temperature of 6,084 K, a radius of 1.083 R☉, a mass of 0.993 M☉, an estimated bolometric luminosity of 1.442 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.5 Gyr and a metallicity of [Fe/H] = -0.2 dex (metal-poor relative to the Sun). From Earth, WASP-28 shines at apparent V-band magnitude 12.274 (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-28 |
| Spectral Type | F8 |
| Effective Temp (Teff) | 6,084 K |
| Stellar Radius | 1.0830 R☉ |
| Stellar Mass | 0.9930 M☉ |
| Bolometric Luminosity | 1.442 L☉ |
| Metallicity [Fe/H] | -0.200 dex |
| Stellar Age | 5.500 Gyr |
| Apparent Magnitude | V: 12.274 · G: 12.029 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.044200 AU |
| Orbital Period | 3.409 days |
| Mean Orbital Velocity | 141.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.5140° |
| Mean Bulk Density | 0.61 g/cm³ (50.9 km/s vesc) |
| Insolation Flux | 695.6500 S⊕ (~946,780 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1136.600 LY (348.494 pc) |