K2-270 c
Astrophysical Synthesis & Habitability Characterization
K2-270 c is a confirmed sub-neptune exoplanet orbiting the star K2-270, located approximately 914.9 light-years (280.52 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1234% across the stellar disk), this world measures 2.95 Earth radii and has a measured mass of 9.01 Earth masses. Combining its mass and radius yields a mean bulk density of 1.94 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.5 km/s.
In its orbital architecture around K2-270, K2-270 c completes one full revolution every 4.4 Earth days at a semi-major axis of 0.0497 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 122.9 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 848 K (+575°C / +1067°F) and receiving 122.77 S⊕ (~167,093 W/m²), K2-270 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-270 is classified as a stellar host with an effective photospheric temperature of 4,877 K, a radius of 0.77 R☉, a mass of 0.85 M☉, an estimated bolometric luminosity of 0.301 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, K2-270 shines at apparent V-band magnitude 13.847 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The K2-270 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-270 c sharing its stellar neighborhood alongside K2-270 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 | K2-270 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,877 K |
| Stellar Radius | 0.7700 R☉ |
| Stellar Mass | 0.8500 M☉ |
| Bolometric Luminosity | 0.301 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.847 · G: 13.470 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049700 AU |
| Orbital Period | 4.4 days |
| Mean Orbital Velocity | 122.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.94 g/cm³ (19.5 km/s vesc) |
| Insolation Flux | 122.7722 S⊕ (~167,093 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 914.900 LY (280.518 pc) |