HD 109246 b
Astrophysical Synthesis & Habitability Characterization
HD 109246 b is a confirmed gas giant exoplanet orbiting the star HD 109246, located approximately 221.2 light-years (67.84 parsecs) from the Solar System. First announced in 2010 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.9 Earth radii (1.24 Jupiter radii) and has a measured mass of 273.334 Earth masses (0.86 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.56 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.41 g⊕ (13.83 m/s²), and an escape velocity of 49.6 km/s.
In its orbital architecture around HD 109246, HD 109246 b completes one full revolution every 68.27 Earth days at a semi-major axis of 0.33 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 52.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 0.2904 AU at periapsis and 0.3696 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 507 K (+234°C / +453°F) and receiving 11.57 S⊕ (~15,744 W/m²), HD 109246 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 109246 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,844 K, a radius of 1.07 R☉, a mass of 1.2 M☉, an estimated bolometric luminosity of 1.198 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, HD 109246 shines at apparent V-band magnitude 8.751 (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 109246 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,844 K |
| Stellar Radius | 1.0700 R☉ |
| Stellar Mass | 1.2000 M☉ |
| Bolometric Luminosity | 1.198 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.751 · G: 8.587 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.330000 AU |
| Orbital Period | 68.27 days |
| Mean Orbital Velocity | 52.6 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.56 g/cm³ (49.6 km/s vesc) |
| Insolation Flux | 11.5680 S⊕ (~15,744 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 221.200 LY (67.835 pc) |