K2-197 b
Astrophysical Synthesis & Habitability Characterization
K2-197 b is a confirmed sub-neptune exoplanet orbiting the star K2-197, located approximately 807.7 light-years (247.64 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0637% across the stellar disk), this world measures 2.56 Earth radii and has a measured mass of 7.08 Earth masses. Combining its mass and radius yields a mean bulk density of 2.33 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.6 km/s.
In its orbital architecture around K2-197, K2-197 b completes one full revolution every 8.358 Earth days at a semi-major axis of 0.0806 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 104.9 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 848 K (+575°C / +1067°F) and receiving 118.45 S⊕ (~161,211 W/m²), K2-197 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-197 is classified as a stellar host with an effective photospheric temperature of 5,667 K, a radius of 0.93 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 0.8 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, K2-197 shines at apparent V-band magnitude 12.199 (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 | K2-197 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,667 K |
| Stellar Radius | 0.9300 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 0.8 L☉ |
| Metallicity [Fe/H] | 0.080 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.199 · G: 11.994 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.080600 AU |
| Orbital Period | 8.358 days |
| Mean Orbital Velocity | 104.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.5093° |
| Mean Bulk Density | 2.33 g/cm³ (18.6 km/s vesc) |
| Insolation Flux | 118.4501 S⊕ (~161,211 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 807.700 LY (247.637 pc) |