HD 109286 b
Astrophysical Synthesis & Habitability Characterization
HD 109286 b is a confirmed gas giant exoplanet orbiting the star HD 109286, located approximately 180.7 light-years (55.42 parsecs) from the Solar System. First announced in 2021 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.2 Earth radii (1.18 Jupiter radii) and has a measured mass of 950.307 Earth masses (2.99 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.28 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.45 g⊕ (53.45 m/s²), and an escape velocity of 94.9 km/s.
In its orbital architecture around HD 109286, HD 109286 b completes one full revolution every 520.1 Earth days (1.42Julian years) at a semi-major axis of 1.259 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 26.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.338, swinging from 0.8335 AU at periapsis out to 1.6845 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.200 R⊕, HD 109286 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 HD 109286 is classified as a solar-type yellow star of spectral type G4 V with an effective photospheric temperature of 5,694 K, a radius of 1.089 R☉, a mass of 0.98 M☉, an estimated bolometric luminosity of 1.118 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, HD 109286 shines at apparent V-band magnitude 8.78 (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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 109286 |
| Spectral Type | G4 V |
| Effective Temp (Teff) | 5,694 K |
| Stellar Radius | 1.0890 R☉ |
| Stellar Mass | 0.9800 M☉ |
| Bolometric Luminosity | 1.118 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.780 · G: 8.616 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.259000 AU |
| Orbital Period | 520.1 days |
| Mean Orbital Velocity | 26.3 km/s |
| Orbital Eccentricity (e) | 0.33800 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.28 g/cm³ (94.9 km/s vesc) |
| Insolation Flux | 0.7090 S⊕ (~965 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 180.700 LY (55.416 pc) |