XO-6 b

Astrophysical Synthesis & Habitability Characterization

XO-6 b is a confirmed gas giant exoplanet orbiting the star XO-6, located approximately 768 light-years (235.48 parsecs) from the Solar System. First announced in 2016 by XO using the Transit detection technique (producing an estimated primary transit depth of 1.2148% across the stellar disk), this world measures 23.203 Earth radii (2.07 Jupiter radii) and has a measured mass of 1398.452 Earth masses (4.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.62 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.6 g⊕ (25.5 m/s²), and an escape velocity of 86.8 km/s.

In its orbital architecture around XO-6, XO-6 b completes one full revolution every 3.765 Earth days at a semi-major axis of 0.0815 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 235.5 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 1577 K (+1304°C / +2379°F) and receiving 580.39 S⊕ (~789,905 W/m²), XO-6 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star XO-6 is classified as a warm F-type star of spectral type F5 with an effective photospheric temperature of 6,720 K, a radius of 1.93 R☉, a mass of 1.47 M☉, an estimated bolometric luminosity of 6.815 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.88 Gyr and a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, XO-6 shines at apparent V-band magnitude 10.247 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: XO · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).