KMT-2024-BLG-1209L b
Astrophysical Synthesis & Habitability Characterization
KMT-2024-BLG-1209L b is a confirmed gas giant exoplanet orbiting the star KMT-2024-BLG-1209L, located approximately 12817.9 light-years (3930 parsecs) from the Solar System. First announced in 2025 by KMTNet using the Microlensing detection technique (detected via relativistic gravitational lensing of a background source star), this world measures 13.2 Earth radii (1.18 Jupiter radii) and has a measured mass of 839.067 Earth masses (2.64 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.01 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 4.82 g⊕ (47.27 m/s²), and an escape velocity of 89.2 km/s.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.200 R⊕, KMT-2024-BLG-1209L 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-2024-BLG-1209L is classified as an orange K-type star of spectral type K3 V with a mass of 0.77 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-2024-BLG-1209L |
| Spectral Type | K3 V |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.7700 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | — |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.510000 AU |
| Orbital Period | — |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.01 g/cm³ (89.2 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 12817.900 LY (3930.000 pc) |