K2-188 b
Astrophysical Synthesis & Habitability Characterization
K2-188 b is a confirmed super-earth exoplanet orbiting the star K2-188, located approximately 1457.3 light-years (446.82 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0108% across the stellar disk), this world measures 1.35 Earth radii and has a measured mass of 2.39 Earth masses. Combining its mass and radius yields a mean bulk density of 5.36 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.31 g⊕ (12.85 m/s²), and an escape velocity of 14.9 km/s.
In its orbital architecture around K2-188, K2-188 b completes one full revolution every 1.742 Earth days at a semi-major axis of 0.0289 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 180.5 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1692 K (+1419°C / +2586°F) and receiving 1,945.70 S⊕ (~2,648,094 W/m²), K2-188 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-188 is classified as a stellar host with an effective photospheric temperature of 5,977 K, a radius of 1.19 R☉, a mass of 1.06 M☉, an estimated bolometric luminosity of 1.621 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, K2-188 shines at apparent V-band magnitude 12.657 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The K2-188 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-188 b sharing its stellar neighborhood alongside K2-188 c.
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 | K2-188 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,977 K |
| Stellar Radius | 1.1900 R☉ |
| Stellar Mass | 1.0600 M☉ |
| Bolometric Luminosity | 1.621 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.657 · G: 12.490 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028900 AU |
| Orbital Period | 1.742 days |
| Mean Orbital Velocity | 180.5 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 83.9282° |
| Mean Bulk Density | 5.36 g/cm³ (14.9 km/s vesc) |
| Insolation Flux | 1945.6975 S⊕ (~2,648,094 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1457.300 LY (446.821 pc) |