Gaia-2 b

Astrophysical Synthesis & Habitability Characterization

Gaia-2 b is a confirmed gas giant exoplanet orbiting the star Gaia-2, located approximately 682.4 light-years (209.23 parsecs) from the Solar System. First announced in 2022 by European Space Agency (ESA) Gaia Satellite using the Transit detection technique (producing an estimated primary transit depth of 1.6302% across the stellar disk), this world measures 14.818 Earth radii (1.32 Jupiter radii) and has a measured mass of 259.666 Earth masses (0.82 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.44 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.18 g⊕ (11.57 m/s²), and an escape velocity of 46.8 km/s.

In its orbital architecture around Gaia-2, Gaia-2 b completes one full revolution every 3.692 Earth days at a semi-major axis of 0.0467 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 137.6 km/s (compared to Earth's 29.8 km/s).

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1213 K (+940°C / +1724°F) and receiving 512.02 S⊕ (~696,864 W/m²), Gaia-2 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Gaia-2 is classified as a stellar host with an effective photospheric temperature of 5,720 K, a radius of 1.064 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 1.087 L☉. From Earth, Gaia-2 shines at apparent V-band magnitude 11.277 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: European Space Agency (ESA) Gaia Satellite · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).