KMT-2017-BLG-2509L b
Astrophysical Synthesis & Habitability Characterization
KMT-2017-BLG-2509L b is a confirmed gas giant exoplanet orbiting the star KMT-2017-BLG-2509L, located approximately 22961.4 light-years (7040 parsecs) from the Solar System. First announced in 2021 by KMTNet using the Microlensing detection technique (detected via relativistic gravitational lensing of a background source star), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 664.261 Earth masses (2.09 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.52 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.7 g⊕ (36.28 m/s²), and an escape velocity of 78.8 km/s.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.400 R⊕, KMT-2017-BLG-2509L 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-2509L is classified as a stellar host with a mass of 0.46 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-2509L |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.4600 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | — |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.140000 AU |
| Orbital Period | — |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.52 g/cm³ (78.8 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 22961.400 LY (7040.000 pc) |