WASP-39 b
Astrophysical Synthesis & Habitability Characterization
WASP-39 b is a confirmed gas giant exoplanet orbiting the star WASP-39, located approximately 697.9 light-years (213.98 parsecs) from the Solar System. First announced in 2011 by SuperWASP using the Transit detection technique (producing an estimated primary transit depth of 1.9591% across the stellar disk), this world measures 14.336 Earth radii (1.28 Jupiter radii) and has a measured mass of 89.31 Earth masses (0.28 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.17 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.43 g⊕ (4.22 m/s²), and an escape velocity of 27.9 km/s.
In its orbital architecture around WASP-39, WASP-39 b completes one full revolution every 4.055 Earth days at a semi-major axis of 0.04828 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 129.5 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 1166 K (+893°C / +1639°F) and receiving 316.27 S⊕ (~430,442 W/m²), WASP-39 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star WASP-39 is classified as a stellar host with an effective photospheric temperature of 5,485 K, a radius of 0.939 R☉, a mass of 0.913 M☉, an estimated bolometric luminosity of 0.716 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.5 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, WASP-39 shines at apparent V-band magnitude 12.095 (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-39 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,485 K |
| Stellar Radius | 0.9390 R☉ |
| Stellar Mass | 0.9130 M☉ |
| Bolometric Luminosity | 0.716 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | 8.500 Gyr |
| Apparent Magnitude | V: 12.095 · G: 11.887 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048280 AU |
| Orbital Period | 4.055 days |
| Mean Orbital Velocity | 129.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.3200° |
| Mean Bulk Density | 0.17 g/cm³ (27.9 km/s vesc) |
| Insolation Flux | 316.2690 S⊕ (~430,442 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 697.900 LY (213.982 pc) |