HD 208487 b
Astrophysical Synthesis & Habitability Characterization
HD 208487 b is a confirmed gas giant exoplanet orbiting the star HD 208487, located approximately 147.2 light-years (45.15 parsecs) from the Solar System. First announced in 2004 by Anglo-Australian Telescope using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14.3 Earth radii (1.28 Jupiter radii) and has a measured mass of 146.201 Earth masses (0.46 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.28 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.71 g⊕ (6.96 m/s²), and an escape velocity of 35.8 km/s.
In its orbital architecture around HD 208487, HD 208487 b completes one full revolution every 129.36 Earth days at a semi-major axis of 0.53 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 44.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.37, swinging from 0.3339 AU at periapsis out to 0.7261 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 438 K (+165°C / +329°F) and receiving 6.09 S⊕ (~8,285 W/m²), HD 208487 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 208487 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 6,134 K, a radius of 1.16 R☉, a mass of 1.15 M☉, an estimated bolometric luminosity of 1.709 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.95 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, HD 208487 shines at apparent V-band magnitude 7.47 (accessible to binoculars and small amateur telescopes) in the Southern 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: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 208487 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 6,134 K |
| Stellar Radius | 1.1600 R☉ |
| Stellar Mass | 1.1500 M☉ |
| Bolometric Luminosity | 1.709 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 1.950 Gyr |
| Apparent Magnitude | V: 7.470 · G: 7.332 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.530000 AU |
| Orbital Period | 129.36 days |
| Mean Orbital Velocity | 44.6 km/s |
| Orbital Eccentricity (e) | 0.37000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.28 g/cm³ (35.8 km/s vesc) |
| Insolation Flux | 6.0876 S⊕ (~8,285 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 147.200 LY (45.147 pc) |