K2-75 c
Astrophysical Synthesis & Habitability Characterization
K2-75 c is a confirmed sub-neptune exoplanet orbiting the star K2-75, located approximately 1832.8 light-years (561.93 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0265% across the stellar disk), this world measures 2.77 Earth radii and has a measured mass of 8.1 Earth masses. Combining its mass and radius yields a mean bulk density of 2.1 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19.1 km/s.
In its orbital architecture around K2-75, K2-75 c completes one full revolution every 18.311 Earth days at a semi-major axis of 0.1429 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 84.9 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 955 K (+682°C / +1260°F) and receiving 138.00 S⊕ (~187,818 W/m²), K2-75 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-75 is classified as a stellar host with an effective photospheric temperature of 5,995 K, a radius of 1.56 R☉, a mass of 1.16 M☉, an estimated bolometric luminosity of 2.82 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.3 dex (metal-rich relative to the Sun). From Earth, K2-75 shines at apparent V-band magnitude 12.803 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-75 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-75 c sharing its stellar neighborhood alongside K2-75 b.
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 | K2-75 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,995 K |
| Stellar Radius | 1.5600 R☉ |
| Stellar Mass | 1.1600 M☉ |
| Bolometric Luminosity | 2.82 L☉ |
| Metallicity [Fe/H] | 0.300 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.803 · G: 12.589 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.142900 AU |
| Orbital Period | 18.311 days |
| Mean Orbital Velocity | 84.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.7961° |
| Mean Bulk Density | 2.1 g/cm³ (19.1 km/s vesc) |
| Insolation Flux | 138.0000 S⊕ (~187,818 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1832.800 LY (561.930 pc) |