K2-240 b
Astrophysical Synthesis & Habitability Characterization
K2-240 b is a confirmed super-earth exoplanet orbiting the star K2-240, located approximately 237.8 light-years (72.91 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1153% across the stellar disk), this world measures 2 Earth radii and has a measured mass of 4.66 Earth masses. Combining its mass and radius yields a mean bulk density of 3.21 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.17 g⊕ (11.47 m/s²), and an escape velocity of 17.1 km/s.
In its orbital architecture around K2-240, K2-240 b completes one full revolution every 6.034 Earth days at a semi-major axis of 0.0513 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 92.5 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 586 K (+313°C / +595°F) and receiving 20.14 S⊕ (~27,409 W/m²), K2-240 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-240 is classified as a low-mass red dwarf of spectral type M0.5 V with an effective photospheric temperature of 3,810 K, a radius of 0.54 R☉, a mass of 0.58 M☉, an estimated bolometric luminosity of 0.055 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, K2-240 shines at apparent V-band magnitude 13.372 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-240 system is a multi-planet architecture hosting 2 confirmed worlds, with K2-240 b sharing its stellar neighborhood alongside K2-240 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 | K2-240 |
| Spectral Type | M0.5 V |
| Effective Temp (Teff) | 3,810 K |
| Stellar Radius | 0.5400 R☉ |
| Stellar Mass | 0.5800 M☉ |
| Bolometric Luminosity | 0.055 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.372 · G: 12.621 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.051300 AU |
| Orbital Period | 6.034 days |
| Mean Orbital Velocity | 92.5 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.2600° |
| Mean Bulk Density | 3.21 g/cm³ (17.1 km/s vesc) |
| Insolation Flux | 20.1392 S⊕ (~27,409 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 237.800 LY (72.911 pc) |