HD 11506 c
Astrophysical Synthesis & Habitability Characterization
HD 11506 c is a confirmed gas giant exoplanet orbiting the star HD 11506, located approximately 167.2 light-years (51.26 parsecs) from the Solar System. First announced in 2008 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 127.131 Earth masses (0.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.26 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.65 g⊕ (6.37 m/s²), and an escape velocity of 33.7 km/s.
In its orbital architecture around HD 11506, HD 11506 c completes one full revolution every 223.92 Earth days at a semi-major axis of 0.771 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 37.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.228 carries the world between 0.5952 AU at periapsis and 0.9468 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 374 K (+101°C / +214°F) and receiving 3.65 S⊕ (~4,973 W/m²), HD 11506 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 11506 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 6,123 K, a radius of 1.24 R☉, a mass of 1.22 M☉, an estimated bolometric luminosity of 1.939 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.5 Gyr and a metallicity of [Fe/H] = 0.3 dex (metal-rich relative to the Sun). From Earth, HD 11506 shines at apparent V-band magnitude 7.51 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 11506 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 11506 c sharing its stellar neighborhood alongside HD 11506 b, HD 11506 d.
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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 11506 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 6,123 K |
| Stellar Radius | 1.2400 R☉ |
| Stellar Mass | 1.2200 M☉ |
| Bolometric Luminosity | 1.939 L☉ |
| Metallicity [Fe/H] | 0.300 dex |
| Stellar Age | 2.500 Gyr |
| Apparent Magnitude | V: 7.510 · G: 7.374 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.771000 AU |
| Orbital Period | 223.92 days |
| Mean Orbital Velocity | 37.5 km/s |
| Orbital Eccentricity (e) | 0.22800 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.26 g/cm³ (33.7 km/s vesc) |
| Insolation Flux | 3.6537 S⊕ (~4,973 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 167.200 LY (51.261 pc) |