K2-387 b
Astrophysical Synthesis & Habitability Characterization
K2-387 b is a confirmed gas giant exoplanet orbiting the star K2-387, located approximately 868.6 light-years (266.32 parsecs) from the Solar System. First announced in 2022 by K2 using the Transit detection technique (producing an estimated primary transit depth of 1.3167% across the stellar disk), this world measures 7.322 Earth radii (0.65 Jupiter radii) and has a measured mass of 42.2 Earth masses (0.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.59 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.79 g⊕ (7.75 m/s²), and an escape velocity of 26.9 km/s.
In its orbital architecture around K2-387, K2-387 b completes one full revolution every 28.735 Earth days.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 7.322 R⊕, K2-387 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star K2-387 is classified as a stellar host with an effective photospheric temperature of 3,572 K, a radius of 0.585 R☉, a mass of 0.57 M☉, an estimated bolometric luminosity of 0.05 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.126 dex (metal-rich relative to the Sun). From Earth, K2-387 shines at apparent V-band magnitude 16.147 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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 | K2-387 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,572 K |
| Stellar Radius | 0.5850 R☉ |
| Stellar Mass | 0.5700 M☉ |
| Bolometric Luminosity | 0.05 L☉ |
| Metallicity [Fe/H] | 0.126 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 16.147 · G: 15.495 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 28.735 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.59 g/cm³ (26.9 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 868.600 LY (266.318 pc) |