gam Lib b
Astrophysical Synthesis & Habitability Characterization
gam Lib b 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 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 357.875 Earth masses (1.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.77 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.91 g⊕ (18.73 m/s²), and an escape velocity of 57.2 km/s.
In its orbital architecture around gam Lib, gam Lib b completes one full revolution every 414.88 Earth days (1.14Julian years) at a semi-major axis of 1.319 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 34.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.16 carries the world between 1.108 AU at periapsis and 1.53 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 721 K (+448°C / +838°F) and receiving 45.37 S⊕ (~61,754 W/m²), gam Lib b 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 b sharing its stellar neighborhood alongside gam Lib c.
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) | 1.319000 AU |
| Orbital Period | 414.88 days |
| Mean Orbital Velocity | 34.6 km/s |
| Orbital Eccentricity (e) | 0.16000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.77 g/cm³ (57.2 km/s vesc) |
| Insolation Flux | 45.3740 S⊕ (~61,754 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 154.600 LY (47.402 pc) |