EPIC 211945201 b

Astrophysical Synthesis & Habitability Characterization

EPIC 211945201 b is a confirmed sub-neptune exoplanet orbiting the star EPIC 211945201, located approximately 592.6 light-years (181.69 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1443% across the stellar disk), this world measures 5.76 Earth radii (0.51 Jupiter radii) and has a measured mass of 11 Earth masses. Combining its mass and radius yields a mean bulk density of 0.32 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.33 g⊕ (3.24 m/s²), and an escape velocity of 15.5 km/s.

In its orbital architecture around EPIC 211945201, EPIC 211945201 b completes one full revolution every 19.492 Earth days at a semi-major axis of 0.1493 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 83.3 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 817 K (+544°C / +1011°F) and receiving 101.00 S⊕ (~137,461 W/m²), EPIC 211945201 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star EPIC 211945201 is classified as a solar-type yellow star of spectral type G0 with an effective photospheric temperature of 6,069 K, a radius of 1.39 R☉, a mass of 1.17 M☉, an estimated bolometric luminosity of 2.352 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.99 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, EPIC 211945201 shines at apparent V-band magnitude 10.154 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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