K2-351 b
Astrophysical Synthesis & Habitability Characterization
K2-351 b is a confirmed sub-neptune exoplanet orbiting the star K2-351, located approximately 2265.9 light-years (694.73 parsecs) from the Solar System. First announced in 2021 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0492% across the stellar disk), this world measures 2.54 Earth radii and has a measured mass of 6.99 Earth masses. Combining its mass and radius yields a mean bulk density of 2.35 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 K2-351, K2-351 b completes one full revolution every 7.806 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 934 K (+661°C / +1222°F), K2-351 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-351 is classified as a stellar host with an effective photospheric temperature of 5,769 K, a radius of 1.05 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 1.096 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, K2-351 shines at apparent V-band magnitude 14.195 (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 | K2-351 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,769 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 1.096 L☉ |
| Metallicity [Fe/H] | 0.080 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.195 · G: 13.985 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 7.806 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.35 g/cm³ (18.6 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2265.900 LY (694.734 pc) |