MOA-2009-BLG-387L b
Astrophysical Synthesis & Habitability Characterization
MOA-2009-BLG-387L b is a confirmed gas giant exoplanet orbiting the star MOA-2009-BLG-387L, located approximately 18558.3 light-years (5690 parsecs) from the Solar System. First announced in 2010 by MOA 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 830 Earth masses (2.61 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.99 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.76 g⊕ (46.68 m/s²), and an escape velocity of 88.7 km/s.
In its orbital architecture around MOA-2009-BLG-387L, MOA-2009-BLG-387L b completes one full revolution every 1980 Earth days (5.42Julian years) at a semi-major axis of 1.8 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 9.9 km/s (compared to Earth's 29.8 km/s).
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.200 R⊕, MOA-2009-BLG-387L 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 MOA-2009-BLG-387L is classified as a stellar host with a mass of 0.19 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: MOA · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | MOA-2009-BLG-387L |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.1900 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | — |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.800000 AU |
| Orbital Period | 1980 days |
| Mean Orbital Velocity | 9.9 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 52.0000° |
| Mean Bulk Density | 1.99 g/cm³ (88.7 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 18558.300 LY (5690.000 pc) |