K2-46 b

Astrophysical Synthesis & Habitability Characterization

K2-46 b is a confirmed sub-neptune exoplanet orbiting the star K2-46, located approximately 1465.2 light-years (449.24 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0212% across the stellar disk), this world measures 2.05 Earth radii and has a measured mass of 4.86 Earth masses. Combining its mass and radius yields a mean bulk density of 3.11 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.2 km/s.

In its orbital architecture around K2-46, K2-46 b completes one full revolution every 19.154 Earth days at a semi-major axis of 0.13821 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 78.5 km/s (compared to Earth's 29.8 km/s).

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 889 K (+616°C / +1141°F) and receiving 119.00 S⊕ (~161,959 W/m²), K2-46 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star K2-46 is classified as a stellar host with an effective photospheric temperature of 6,256 K, a radius of 1.29 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 2.287 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.32 dex (metal-poor relative to the Sun). From Earth, K2-46 shines at apparent V-band magnitude 12.144 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

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