K2-182 b

Astrophysical Synthesis & Habitability Characterization

K2-182 b is a confirmed sub-neptune exoplanet orbiting the star K2-182, located approximately 505 light-years (154.83 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0994% across the stellar disk), this world measures 2.713 Earth radii and has a measured mass of 20.977 Earth masses. Combining its mass and radius yields a mean bulk density of 5.79 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 2.85 g⊕ (27.95 m/s²), and an escape velocity of 31.1 km/s.

In its orbital architecture around K2-182, K2-182 b completes one full revolution every 4.737 Earth days at a semi-major axis of 0.05174 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 118.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.071 carries the world between 0.0481 AU at periapsis and 0.0554 AU at apoapsis, driving measurable seasonal insolation cycles.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 966 K (+693°C / +1279°F) and receiving 146.90 S⊕ (~199,931 W/m²), K2-182 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star K2-182 is classified as a stellar host with an effective photospheric temperature of 5,128 K, a radius of 0.789 R☉, a mass of 0.823 M☉, an estimated bolometric luminosity of 0.386 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.2 Gyr and a metallicity of [Fe/H] = 0.022 dex (near-solar heavy-element abundance). From Earth, K2-182 shines at apparent V-band magnitude 11.833 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).