K2-100 b
Astrophysical Synthesis & Habitability Characterization
K2-100 b is a confirmed sub-neptune exoplanet orbiting the star K2-100, located approximately 616.3 light-years (188.96 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0823% across the stellar disk), this world measures 3.88 Earth radii (0.35 Jupiter radii) and has a measured mass of 21.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.06 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.45 g⊕ (14.22 m/s²), and an escape velocity of 26.5 km/s.
In its orbital architecture around K2-100, K2-100 b completes one full revolution every 1.674 Earth days at a semi-major axis of 0.0301 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 195.6 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1841 K (+1568°C / +2854°F) and receiving 1,915.00 S⊕ (~2,606,315 W/m²), K2-100 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-100 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,945 K, a radius of 1.24 R☉, a mass of 1.15 M☉, an estimated bolometric luminosity of 1.723 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.75 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, K2-100 shines at apparent V-band magnitude 10.651 (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 | K2-100 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,945 K |
| Stellar Radius | 1.2400 R☉ |
| Stellar Mass | 1.1500 M☉ |
| Bolometric Luminosity | 1.723 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 0.750 Gyr |
| Apparent Magnitude | V: 10.651 · G: 10.405 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.030100 AU |
| Orbital Period | 1.674 days |
| Mean Orbital Velocity | 195.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 81.2700° |
| Mean Bulk Density | 2.06 g/cm³ (26.5 km/s vesc) |
| Insolation Flux | 1915.0000 S⊕ (~2,606,315 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 616.300 LY (188.959 pc) |