K2-318 b
Astrophysical Synthesis & Habitability Characterization
K2-318 b is a confirmed super-earth exoplanet orbiting the star K2-318, located approximately 482.3 light-years (147.87 parsecs) from the Solar System. First announced in 2020 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.076% across the stellar disk), this world measures 1.66 Earth radii and has a measured mass of 3.39 Earth masses. Combining its mass and radius yields a mean bulk density of 4.09 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.23 g⊕ (12.06 m/s²), and an escape velocity of 16 km/s.
In its orbital architecture around K2-318, K2-318 b completes one full revolution every 7.01 Earth days at a semi-major axis of 0.0911 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 141.4 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 456 K (+183°C / +361°F) and receiving 6.37 S⊕ (~8,667 W/m²), K2-318 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-318 is classified as a stellar host with an effective photospheric temperature of 3,851 K, a radius of 0.552 R☉, a mass of 0.561 M☉, an estimated bolometric luminosity of 0.06 L☉. From Earth, K2-318 shines at apparent V-band magnitude 15.8 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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 | K2-318 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,851 K |
| Stellar Radius | 0.5520 R☉ |
| Stellar Mass | 0.5610 M☉ |
| Bolometric Luminosity | 0.06 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 15.800 · G: 14.397 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091100 AU |
| Orbital Period | 7.01 days |
| Mean Orbital Velocity | 141.4 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.3800° |
| Mean Bulk Density | 4.09 g/cm³ (16 km/s vesc) |
| Insolation Flux | 6.3680 S⊕ (~8,667 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 482.300 LY (147.866 pc) |