K2-326 b
Astrophysical Synthesis & Habitability Characterization
K2-326 b is a confirmed sub-neptune exoplanet orbiting the star K2-326, located approximately 920.8 light-years (282.31 parsecs) from the Solar System. First announced in 2020 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0923% across the stellar disk), this world measures 2.28 Earth radii and has a measured mass of 5.82 Earth masses. Combining its mass and radius yields a mean bulk density of 2.71 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.9 km/s.
In its orbital architecture around K2-326, K2-326 b completes one full revolution every 1.256 Earth days at a semi-major axis of 0.0198 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 171.5 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1114 K (+841°C / +1546°F) and receiving 268.13 S⊕ (~364,923 W/m²), K2-326 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-326 is classified as a stellar host with an effective photospheric temperature of 3,924 K, a radius of 0.688 R☉, a mass of 0.507 M☉, an estimated bolometric luminosity of 0.101 L☉. From Earth, K2-326 shines at apparent V-band magnitude 15.982 (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 | K2-326 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,924 K |
| Stellar Radius | 0.6880 R☉ |
| Stellar Mass | 0.5070 M☉ |
| Bolometric Luminosity | 0.101 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 15.982 · G: 15.008 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.019800 AU |
| Orbital Period | 1.256 days |
| Mean Orbital Velocity | 171.5 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 85.6300° |
| Mean Bulk Density | 2.71 g/cm³ (17.9 km/s vesc) |
| Insolation Flux | 268.1283 S⊕ (~364,923 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 920.800 LY (282.308 pc) |