K2-284 b
Astrophysical Synthesis & Habitability Characterization
K2-284 b is a confirmed sub-neptune exoplanet orbiting the star K2-284, located approximately 349.9 light-years (107.27 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1763% across the stellar disk), this world measures 2.78 Earth radii and has a measured mass of 8.15 Earth masses. Combining its mass and radius yields a mean bulk density of 2.09 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.
In its orbital architecture around K2-284, K2-284 b completes one full revolution every 4.795 Earth days at a semi-major axis of 0.04771 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 108.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.078 carries the world between 0.044 AU at periapsis and 0.0514 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 653 K (+380°C / +716°F) and receiving 42.60 S⊕ (~57,979 W/m²), K2-284 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-284 is classified as a stellar host with an effective photospheric temperature of 4,140 K, a radius of 0.607 R☉, a mass of 0.63 M☉, an estimated bolometric luminosity of 0.097 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.12 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, K2-284 shines at apparent V-band magnitude 13.265 (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 | K2-284 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,140 K |
| Stellar Radius | 0.6070 R☉ |
| Stellar Mass | 0.6300 M☉ |
| Bolometric Luminosity | 0.097 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 0.120 Gyr |
| Apparent Magnitude | V: 13.265 · G: 12.860 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047710 AU |
| Orbital Period | 4.795 days |
| Mean Orbital Velocity | 108.2 km/s |
| Orbital Eccentricity (e) | 0.07800 |
| Orbital Inclination (i) | 89.0000° |
| Mean Bulk Density | 2.09 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 42.6000 S⊕ (~57,979 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 349.900 LY (107.272 pc) |