K2-275 c
Astrophysical Synthesis & Habitability Characterization
K2-275 c is a confirmed sub-neptune exoplanet orbiting the star K2-275, located approximately 402.6 light-years (123.44 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0862% across the stellar disk), this world measures 2.21 Earth radii and has a measured mass of 5.52 Earth masses. Combining its mass and radius yields a mean bulk density of 2.82 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 K2-275, K2-275 c completes one full revolution every 8.439 Earth days at a semi-major axis of 0.0881 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 113.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 653 K (+380°C / +716°F) and receiving 45.76 S⊕ (~62,276 W/m²), K2-275 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-275 is classified as a stellar host with an effective photospheric temperature of 4,841 K, a radius of 0.69 R☉, a mass of 0.77 M☉, an estimated bolometric luminosity of 0.235 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, K2-275 shines at apparent V-band magnitude 11.974 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The K2-275 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-275 c sharing its stellar neighborhood alongside K2-275 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 | K2-275 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,841 K |
| Stellar Radius | 0.6900 R☉ |
| Stellar Mass | 0.7700 M☉ |
| Bolometric Luminosity | 0.235 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.974 · G: 11.814 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.088100 AU |
| Orbital Period | 8.439 days |
| Mean Orbital Velocity | 113.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.82 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | 45.7572 S⊕ (~62,276 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 402.600 LY (123.438 pc) |