K2-249 b
Astrophysical Synthesis & Habitability Characterization
K2-249 b is a confirmed sub-neptune exoplanet orbiting the star K2-249, located approximately 1701.6 light-years (521.72 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0265% across the stellar disk), this world measures 2.79 Earth radii and has a measured mass of 8.2 Earth masses. Combining its mass and radius yields a mean bulk density of 2.08 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.
In its orbital architecture around K2-249, K2-249 b completes one full revolution every 12.409 Earth days at a semi-major axis of 0.1151 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 100.9 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1061 K (+788°C / +1450°F) and receiving 163.73 S⊕ (~222,833 W/m²), K2-249 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-249 is classified as a stellar host with an effective photospheric temperature of 6,504 K, a radius of 1.57 R☉, a mass of 1.32 M☉, an estimated bolometric luminosity of 3.957 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, K2-249 shines at apparent V-band magnitude 12.646 (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 | K2-249 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,504 K |
| Stellar Radius | 1.5700 R☉ |
| Stellar Mass | 1.3200 M☉ |
| Bolometric Luminosity | 3.957 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.646 · G: 12.450 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.115100 AU |
| Orbital Period | 12.409 days |
| Mean Orbital Velocity | 100.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.08 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 163.7274 S⊕ (~222,833 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1701.600 LY (521.716 pc) |