K2-10 b
Astrophysical Synthesis & Habitability Characterization
K2-10 b is a confirmed sub-neptune exoplanet orbiting the star K2-10, located approximately 888.3 light-years (272.36 parsecs) from the Solar System. First announced in 2015 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1309% across the stellar disk), this world measures 3.773 Earth radii (0.34 Jupiter radii) and has a measured mass of 25.2 Earth masses. Combining its mass and radius yields a mean bulk density of 2.59 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.77 g⊕ (17.36 m/s²), and an escape velocity of 28.9 km/s.
In its orbital architecture around K2-10, K2-10 b completes one full revolution every 19.306 Earth days at a semi-major axis of 0.137 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 77.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.31, swinging from 0.0945 AU at periapsis out to 0.1795 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 649 K (+376°C / +709°F) and receiving 42.10 S⊕ (~57,298 W/m²), K2-10 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-10 is classified as a warm F-type star of spectral type F9 with an effective photospheric temperature of 5,533 K, a radius of 0.956 R☉, a mass of 0.88 M☉, an estimated bolometric luminosity of 0.769 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.07 dex (near-solar heavy-element abundance). From Earth, K2-10 shines at apparent V-band magnitude 12.429 (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 | K2-10 |
| Spectral Type | F9 |
| Effective Temp (Teff) | 5,533 K |
| Stellar Radius | 0.9560 R☉ |
| Stellar Mass | 0.8800 M☉ |
| Bolometric Luminosity | 0.769 L☉ |
| Metallicity [Fe/H] | -0.070 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.429 · G: 12.216 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.137000 AU |
| Orbital Period | 19.306 days |
| Mean Orbital Velocity | 77.2 km/s |
| Orbital Eccentricity (e) | 0.31000 |
| Orbital Inclination (i) | 89.5041° |
| Mean Bulk Density | 2.59 g/cm³ (28.9 km/s vesc) |
| Insolation Flux | 42.1000 S⊕ (~57,298 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 888.300 LY (272.360 pc) |