K2-68 b
Astrophysical Synthesis & Habitability Characterization
K2-68 b is a confirmed super-earth exoplanet orbiting the star K2-68, located approximately 550.1 light-years (168.65 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0461% across the stellar disk), this world measures 1.58 Earth radii and has a measured mass of 3.12 Earth masses. Combining its mass and radius yields a mean bulk density of 4.36 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.25 g⊕ (12.26 m/s²), and an escape velocity of 15.7 km/s.
In its orbital architecture around K2-68, K2-68 b completes one full revolution every 8.054 Earth days at a semi-major axis of 0.0708 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 707 K (+434°C / +813°F) and receiving 41.00 S⊕ (~55,801 W/m²), K2-68 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-68 is classified as a stellar host with an effective photospheric temperature of 4,746 K, a radius of 0.675 R☉, a mass of 0.73 M☉, an estimated bolometric luminosity of 0.207 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.21 dex (metal-poor relative to the Sun). From Earth, K2-68 shines at apparent V-band magnitude 12.987 (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 | K2-68 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,746 K |
| Stellar Radius | 0.6750 R☉ |
| Stellar Mass | 0.7300 M☉ |
| Bolometric Luminosity | 0.207 L☉ |
| Metallicity [Fe/H] | -0.210 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.987 · G: 12.657 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.070800 AU |
| Orbital Period | 8.054 days |
| Mean Orbital Velocity | 95.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.7153° |
| Mean Bulk Density | 4.36 g/cm³ (15.7 km/s vesc) |
| Insolation Flux | 41.0000 S⊕ (~55,801 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 550.100 LY (168.652 pc) |