HD 149806 b
Astrophysical Synthesis & Habitability Characterization
HD 149806 b is a confirmed gas giant exoplanet orbiting the star HD 149806, located approximately 66.1 light-years (20.27 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.3 Earth radii (1.1 Jupiter radii) and has a measured mass of 4003.684 Earth masses (12.6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 11.86 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 26.46 g⊕ (259.48 m/s²), and an escape velocity of 201.8 km/s.
In its orbital architecture around HD 149806, HD 149806 b completes one full revolution every 16521.528 Earth days (45.23Julian years) at a semi-major axis of 12.404 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 8.2 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.357, swinging from 7.9758 AU at periapsis out to 16.8322 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 69 K (-204°C / -335°F) and an incident flux of 0.00 S⊕ (~5 W/m²), surface water and volatile species on HD 149806 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 149806 is classified as an orange K-type star of spectral type K0V with an effective photospheric temperature of 5,352 K, a radius of 0.89 R☉, a mass of 0.93 M☉, an estimated bolometric luminosity of 0.583 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.36 Gyr and a metallicity of [Fe/H] = 0.221 dex (metal-rich relative to the Sun). From Earth, HD 149806 shines at apparent V-band magnitude 7.083 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere.
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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 149806 |
| Spectral Type | K0V |
| Effective Temp (Teff) | 5,352 K |
| Stellar Radius | 0.8900 R☉ |
| Stellar Mass | 0.9300 M☉ |
| Bolometric Luminosity | 0.583 L☉ |
| Metallicity [Fe/H] | 0.221 dex |
| Stellar Age | 8.360 Gyr |
| Apparent Magnitude | V: 7.083 · G: 6.868 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 12.404000 AU |
| Orbital Period | 16521.528 days |
| Mean Orbital Velocity | 8.2 km/s |
| Orbital Eccentricity (e) | 0.35700 |
| Orbital Inclination (i) | 13.5740° |
| Mean Bulk Density | 11.86 g/cm³ (201.8 km/s vesc) |
| Insolation Flux | 0.0037 S⊕ (~5 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 66.100 LY (20.273 pc) |