K2-250 b
Astrophysical Synthesis & Habitability Characterization
K2-250 b is a confirmed sub-neptune exoplanet orbiting the star K2-250, located approximately 1352.6 light-years (414.71 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0974% across the stellar disk), this world measures 2.713 Earth radii and has a measured mass of 7.81 Earth masses. Combining its mass and radius yields a mean bulk density of 2.16 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19 km/s.
In its orbital architecture around K2-250, K2-250 b completes one full revolution every 4.014 Earth days at a semi-major axis of 0.04606 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 124.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.21 carries the world between 0.0364 AU at periapsis and 0.0557 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1003 K (+730°C / +1346°F) and receiving 169.22 S⊕ (~230,306 W/m²), K2-250 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-250 is classified as a stellar host with an effective photospheric temperature of 5,003 K, a radius of 0.797 R☉, a mass of 0.809 M☉, an estimated bolometric luminosity of 0.357 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.2 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, K2-250 shines at apparent V-band magnitude 14.314 (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 | K2-250 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,003 K |
| Stellar Radius | 0.7970 R☉ |
| Stellar Mass | 0.8090 M☉ |
| Bolometric Luminosity | 0.357 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 8.200 Gyr |
| Apparent Magnitude | V: 14.314 · G: 13.973 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.046060 AU |
| Orbital Period | 4.014 days |
| Mean Orbital Velocity | 124.8 km/s |
| Orbital Eccentricity (e) | 0.21000 |
| Orbital Inclination (i) | 88.2600° |
| Mean Bulk Density | 2.16 g/cm³ (19 km/s vesc) |
| Insolation Flux | 169.2180 S⊕ (~230,306 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1352.600 LY (414.708 pc) |