K2-220 b
Astrophysical Synthesis & Habitability Characterization
K2-220 b is a confirmed sub-neptune exoplanet orbiting the star K2-220, located approximately 761.6 light-years (233.51 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0448% across the stellar disk), this world measures 2.37 Earth radii and has a measured mass of 6.21 Earth masses. Combining its mass and radius yields a mean bulk density of 2.57 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 18.1 km/s.
In its orbital architecture around K2-220, K2-220 b completes one full revolution every 13.682 Earth days at a semi-major axis of 0.1104 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.8 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 761 K (+488°C / +910°F) and receiving 79.70 S⊕ (~108,472 W/m²), K2-220 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-220 is classified as a stellar host with an effective photospheric temperature of 5,612 K, a radius of 1.026 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 0.937 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.05 dex (near-solar heavy-element abundance). From Earth, K2-220 shines at apparent V-band magnitude 11.873 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-220 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,612 K |
| Stellar Radius | 1.0260 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 0.937 L☉ |
| Metallicity [Fe/H] | -0.050 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.873 · G: 11.721 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.110400 AU |
| Orbital Period | 13.682 days |
| Mean Orbital Velocity | 87.8 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.8835° |
| Mean Bulk Density | 2.57 g/cm³ (18.1 km/s vesc) |
| Insolation Flux | 79.7000 S⊕ (~108,472 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 761.600 LY (233.514 pc) |