KMT-2021-BLG-1253L b
Astrophysical Synthesis & Habitability Characterization
KMT-2021-BLG-1253L b is a confirmed sub-neptune exoplanet orbiting the star KMT-2021-BLG-1253L, located approximately 21656.8 light-years (6640 parsecs) from the Solar System. First announced in 2022 by KMTNet using the Microlensing detection technique (detected via relativistic gravitational lensing of a background source star), this world measures 4.59 Earth radii (0.41 Jupiter radii) and has a measured mass of 19.05 Earth masses. Combining its mass and radius yields a mean bulk density of 1.09 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 22.8 km/s.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 4.590 R⊕, KMT-2021-BLG-1253L 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-2021-BLG-1253L is classified as a stellar host with a mass of 0.24 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-2021-BLG-1253L |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.2400 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | — |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.520000 AU |
| Orbital Period | — |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.09 g/cm³ (22.8 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 21656.800 LY (6640.000 pc) |