KMT-2017-BLG-0428L b
Astrophysical Synthesis & Habitability Characterization
KMT-2017-BLG-0428L b is a confirmed sub-neptune exoplanet orbiting the star KMT-2017-BLG-0428L, located approximately 17612.4 light-years (5400 parsecs) from the Solar System. First announced in 2023 by KMTNet using the Microlensing detection technique (detected via relativistic gravitational lensing of a background source star), this world measures 2.23 Earth radii and has a measured mass of 5.59 Earth masses. Combining its mass and radius yields a mean bulk density of 2.78 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.7 km/s.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.230 R⊕, KMT-2017-BLG-0428L 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 KMT-2017-BLG-0428L is classified as a stellar host with a mass of 0.34 M☉.
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: KMTNet · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KMT-2017-BLG-0428L |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.3400 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | — |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.810000 AU |
| Orbital Period | — |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.78 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 17612.400 LY (5400.000 pc) |