WASP-98 b
Astrophysical Synthesis & Habitability Characterization
WASP-98 b is a confirmed gas giant exoplanet orbiting the star WASP-98, located approximately 918.9 light-years (281.74 parsecs) from the Solar System. First announced in 2014 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 2.517% across the stellar disk), this world measures 12.823 Earth radii (1.14 Jupiter radii) and has a measured mass of 293.039 Earth masses (0.92 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.77 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.78 g⊕ (17.46 m/s²), and an escape velocity of 53.5 km/s.
In its orbital architecture around WASP-98, WASP-98 b completes one full revolution every 2.963 Earth days at a semi-major axis of 0.03762 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 138.1 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 1171 K (+898°C / +1648°F) and receiving 269.88 S⊕ (~367,310 W/m²), WASP-98 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-98 is classified as a solar-type yellow star of spectral type G7 with an effective photospheric temperature of 5,473 K, a radius of 0.741 R☉, a mass of 0.809 M☉, an estimated bolometric luminosity of 0.442 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.7 Gyr and a metallicity of [Fe/H] = -0.49 dex (metal-poor relative to the Sun). From Earth, WASP-98 shines at apparent V-band magnitude 13.252 (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-98 |
| Spectral Type | G7 |
| Effective Temp (Teff) | 5,473 K |
| Stellar Radius | 0.7410 R☉ |
| Stellar Mass | 0.8090 M☉ |
| Bolometric Luminosity | 0.442 L☉ |
| Metallicity [Fe/H] | -0.490 dex |
| Stellar Age | 2.700 Gyr |
| Apparent Magnitude | V: 13.252 · G: 12.868 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.037620 AU |
| Orbital Period | 2.963 days |
| Mean Orbital Velocity | 138.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.3800° |
| Mean Bulk Density | 0.77 g/cm³ (53.5 km/s vesc) |
| Insolation Flux | 269.8828 S⊕ (~367,310 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 918.900 LY (281.742 pc) |