HD 11755 b
Astrophysical Synthesis & Habitability Characterization
HD 11755 b is a confirmed gas giant exoplanet orbiting the star HD 11755, located approximately 766.6 light-years (235.05 parsecs) from the Solar System. First announced in 2015 by Bohyunsan Optical Astronomical Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1789.383 Earth masses (5.63 Jupiter masses). Combining its mass and radius yields a mean bulk density of 4.7 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 10.92 g⊕ (107.09 m/s²), and an escape velocity of 132.3 km/s.
In its orbital architecture around HD 11755, HD 11755 b completes one full revolution every 433.7 Earth days (1.19Julian years) at a semi-major axis of 1.09 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 27.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.19 carries the world between 0.8829 AU at periapsis and 1.2971 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 903 K (+630°C / +1166°F) and receiving 124.30 S⊕ (~169,175 W/m²), HD 11755 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 11755 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 4,312 K, a radius of 20.58 R☉, a mass of 0.72 M☉, an estimated bolometric luminosity of 131.37 L☉. Stellar evolution modeling indicates an estimated stellar age of 10.2 Gyr and a metallicity of [Fe/H] = -0.74 dex (metal-poor relative to the Sun). From Earth, HD 11755 shines at apparent V-band magnitude 6.883 (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: Bohyunsan Optical Astronomical Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 11755 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 4,312 K |
| Stellar Radius | 20.5800 R☉ |
| Stellar Mass | 0.7200 M☉ |
| Bolometric Luminosity | 131.37 L☉ |
| Metallicity [Fe/H] | -0.740 dex |
| Stellar Age | 10.200 Gyr |
| Apparent Magnitude | V: 6.883 · G: 6.464 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.090000 AU |
| Orbital Period | 433.7 days |
| Mean Orbital Velocity | 27.3 km/s |
| Orbital Eccentricity (e) | 0.19000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 4.7 g/cm³ (132.3 km/s vesc) |
| Insolation Flux | 124.3021 S⊕ (~169,175 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 766.600 LY (235.045 pc) |