K2-264 b
Astrophysical Synthesis & Habitability Characterization
K2-264 b is a confirmed sub-neptune exoplanet orbiting the star K2-264, located approximately 605.4 light-years (185.61 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.187% across the stellar disk), this world measures 2.231 Earth radii and has a measured mass of 5.61 Earth masses. Combining its mass and radius yields a mean bulk density of 2.79 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.7 km/s.
In its orbital architecture around K2-264, K2-264 b completes one full revolution every 5.84 Earth days at a semi-major axis of 0.05023 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 93.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.5, swinging from 0.0251 AU at periapsis out to 0.0753 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 496 K (+223°C / +433°F) and receiving 13.08 S⊕ (~17,801 W/m²), K2-264 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-264 is classified as a low-mass red dwarf of spectral type M2.5 V with an effective photospheric temperature of 3,660 K, a radius of 0.473 R☉, a mass of 0.496 M☉, an estimated bolometric luminosity of 0.036 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.013 dex (near-solar heavy-element abundance). From Earth, K2-264 shines at apparent V-band magnitude 16.701 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The K2-264 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-264 b sharing its stellar neighborhood alongside K2-264 c.
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 | K2-264 |
| Spectral Type | M2.5 V |
| Effective Temp (Teff) | 3,660 K |
| Stellar Radius | 0.4730 R☉ |
| Stellar Mass | 0.4960 M☉ |
| Bolometric Luminosity | 0.036 L☉ |
| Metallicity [Fe/H] | -0.013 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 16.701 · G: 15.663 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050230 AU |
| Orbital Period | 5.84 days |
| Mean Orbital Velocity | 93.6 km/s |
| Orbital Eccentricity (e) | 0.50000 |
| Orbital Inclination (i) | 89.0100° |
| Mean Bulk Density | 2.79 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | 13.0794 S⊕ (~17,801 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 605.400 LY (185.605 pc) |