KELT-20 b

Astrophysical Synthesis & Habitability Characterization

KELT-20 b is a confirmed gas giant exoplanet orbiting the star KELT-20, located approximately 445 light-years (136.43 parsecs) from the Solar System. First announced in 2017 by KELT-North using the Transit detection technique (producing an estimated primary transit depth of 1.3069% across the stellar disk), this world measures 19.515 Earth radii (1.74 Jupiter radii) and has a measured mass of 1074.901 Earth masses (3.38 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.8 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.82 g⊕ (27.65 m/s²), and an escape velocity of 83 km/s.

In its orbital architecture around KELT-20, KELT-20 b completes one full revolution every 3.474 Earth days at a semi-major axis of 0.0542 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 169.7 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 2262 K (+1989°C / +3612°F) and receiving 4,362.50 S⊕ (~5,937,363 W/m²), KELT-20 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star KELT-20 is classified as a luminous A-type star of spectral type A2 V with an effective photospheric temperature of 8,720 K, a radius of 1.565 R☉, a mass of 1.76 M☉, an estimated bolometric luminosity of 12.705 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.6 Gyr and a metallicity of [Fe/H] = -0.29 dex (metal-poor relative to the Sun). From Earth, KELT-20 shines at apparent V-band magnitude 7.59 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.

Discovery Facility: KELT-North · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).