K2-101 b

Astrophysical Synthesis & Habitability Characterization

K2-101 b is a confirmed super-earth exoplanet orbiting the star K2-101, located approximately 614.2 light-years (188.33 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0582% across the stellar disk), this world measures 2 Earth radii and has a measured mass of 4.66 Earth masses. Combining its mass and radius yields a mean bulk density of 3.21 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.17 g⊕ (11.47 m/s²), and an escape velocity of 17.1 km/s.

In its orbital architecture around K2-101, K2-101 b completes one full revolution every 14.676 Earth days at a semi-major axis of 0.1124 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). Its moderate orbital eccentricity of e = 0.1 carries the world between 0.1012 AU at periapsis and 0.1236 AU at apoapsis, driving measurable seasonal insolation cycles.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 618 K (+345°C / +653°F) and receiving 20.12 S⊕ (~27,384 W/m²), K2-101 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star K2-101 is classified as an orange K-type star of spectral type K3 with an effective photospheric temperature of 4,927 K, a radius of 0.76 R☉, a mass of 0.82 M☉, an estimated bolometric luminosity of 0.305 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.79 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, K2-101 shines at apparent V-band magnitude 12.892 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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