WASP-87 b

Astrophysical Synthesis & Habitability Characterization

WASP-87 b is a confirmed gas giant exoplanet orbiting the star WASP-87, located approximately 973.2 light-years (298.39 parsecs) from the Solar System. First announced in 2016 by Anglo-Australian Telescope using the Transit detection technique (producing an estimated primary transit depth of 0.7652% across the stellar disk), this world measures 15.524 Earth radii (1.38 Jupiter radii) and has a measured mass of 692.869 Earth masses (2.18 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.02 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.88 g⊕ (28.24 m/s²), and an escape velocity of 74.7 km/s.

In its orbital architecture around WASP-87, WASP-87 b completes one full revolution every 1.683 Earth days at a semi-major axis of 0.02946 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 190.5 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 2050 K (+1777°C / +3231°F) and receiving 4,170.10 S⊕ (~5,675,501 W/m²), WASP-87 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star WASP-87 is classified as a stellar host with an effective photospheric temperature of 6,450 K, a radius of 1.627 R☉, a mass of 1.204 M☉, an estimated bolometric luminosity of 4.111 L☉. From Earth, WASP-87 shines at apparent V-band magnitude 10.727 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

Discovery Facility: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).