gam Lib c
Astrophysical Synthesis & Habitability Characterization
gam Lib c is a confirmed gas giant exoplanet orbiting the star gam Lib, located approximately 154.6 light-years (47.4 parsecs) from the Solar System. First announced in 2018 by Okayama Astrophysical Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1662.56 Earth masses (5.23 Jupiter masses). Combining its mass and radius yields a mean bulk density of 4.37 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 10.15 g⊕ (99.54 m/s²), and an escape velocity of 127.5 km/s.
In its orbital architecture around gam Lib, gam Lib c completes one full revolution every 966.49 Earth days (2.65Julian years) at a semi-major axis of 2.318 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 26.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.065 carries the world between 2.1673 AU at periapsis and 2.4687 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 544 K (+271°C / +520°F) and receiving 14.69 S⊕ (~19,995 W/m²), gam Lib c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star gam Lib is classified as an orange K-type star of spectral type K0 III with an effective photospheric temperature of 4,879 K, a radius of 12.38 R☉, a mass of 1.78 M☉, an estimated bolometric luminosity of 77.921 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.82 Gyr and a metallicity of [Fe/H] = -0.27 dex (metal-poor relative to the Sun). From Earth, gam Lib shines at apparent V-band magnitude 3.907 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere. The gam Lib system is a multi-planet architecture hosting 2 confirmed worlds, with gam Lib c sharing its stellar neighborhood alongside gam Lib b.
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: Okayama Astrophysical Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | gam Lib |
| Spectral Type | K0 III |
| Effective Temp (Teff) | 4,879 K |
| Stellar Radius | 12.3800 R☉ |
| Stellar Mass | 1.7800 M☉ |
| Bolometric Luminosity | 77.921 L☉ |
| Metallicity [Fe/H] | -0.270 dex |
| Stellar Age | 2.820 Gyr |
| Apparent Magnitude | V: 3.907 · G: 3.649 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.318000 AU |
| Orbital Period | 966.49 days |
| Mean Orbital Velocity | 26.1 km/s |
| Orbital Eccentricity (e) | 0.06500 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 4.37 g/cm³ (127.5 km/s vesc) |
| Insolation Flux | 14.6916 S⊕ (~19,995 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 154.600 LY (47.402 pc) |