HAT-P-69 b

Astrophysical Synthesis & Habitability Characterization

HAT-P-69 b is a confirmed gas giant exoplanet orbiting the star HAT-P-69, located approximately 1113 light-years (341.26 parsecs) from the Solar System. First announced in 2019 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 0.7996% across the stellar disk), this world measures 18.786 Earth radii (1.68 Jupiter radii) and has a measured mass of 1137.831 Earth masses (3.58 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.95 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.22 g⊕ (31.58 m/s²), and an escape velocity of 87.1 km/s.

In its orbital architecture around HAT-P-69, HAT-P-69 b completes one full revolution every 4.787 Earth days at a semi-major axis of 0.06555 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 149 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 1930 K (+1657°C / +3015°F) and receiving 2,320.18 S⊕ (~3,157,765 W/m²), HAT-P-69 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star HAT-P-69 is classified as a stellar host with an effective photospheric temperature of 7,394 K, a radius of 1.926 R☉, a mass of 1.648 M☉, an estimated bolometric luminosity of 9.948 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.27 Gyr and a metallicity of [Fe/H] = -0.069 dex (near-solar heavy-element abundance). From Earth, HAT-P-69 shines at apparent V-band magnitude 9.774 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.

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