K2-287 b
Astrophysical Synthesis & Habitability Characterization
K2-287 b is a confirmed gas giant exoplanet orbiting the star K2-287, located approximately 516.4 light-years (158.34 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.6617% across the stellar disk), this world measures 9.494 Earth radii (0.85 Jupiter radii) and has a measured mass of 100.116 Earth masses (0.31 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.65 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 36.3 km/s.
In its orbital architecture around K2-287, K2-287 b completes one full revolution every 14.893 Earth days at a semi-major axis of 0.1206 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 88.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.478, swinging from 0.063 AU at periapsis out to 0.1782 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 804 K (+531°C / +988°F) and receiving 53.58 S⊕ (~72,924 W/m²), K2-287 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-287 is classified as a stellar host with an effective photospheric temperature of 5,695 K, a radius of 1.07 R☉, a mass of 1.056 M☉, an estimated bolometric luminosity of 1.081 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.5 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, K2-287 shines at apparent V-band magnitude 11.41 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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 | K2-287 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,695 K |
| Stellar Radius | 1.0700 R☉ |
| Stellar Mass | 1.0560 M☉ |
| Bolometric Luminosity | 1.081 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 4.500 Gyr |
| Apparent Magnitude | V: 11.410 · G: 11.067 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.120600 AU |
| Orbital Period | 14.893 days |
| Mean Orbital Velocity | 88.1 km/s |
| Orbital Eccentricity (e) | 0.47800 |
| Orbital Inclination (i) | 88.1300° |
| Mean Bulk Density | 0.65 g/cm³ (36.3 km/s vesc) |
| Insolation Flux | 53.5814 S⊕ (~72,924 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 516.400 LY (158.335 pc) |