HD 11964 b
Astrophysical Synthesis & Habitability Characterization
HD 11964 b is a confirmed gas giant exoplanet orbiting the star HD 11964, located approximately 109.4 light-years (33.54 parsecs) from the Solar System. First announced in 2005 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 14.1 Earth radii (1.26 Jupiter radii) and has a measured mass of 198 Earth masses (0.62 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.39 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1 g⊕ (9.81 m/s²), and an escape velocity of 41.9 km/s.
In its orbital architecture around HD 11964, HD 11964 b completes one full revolution every 1945 Earth days (5.33Julian years) at a semi-major axis of 3.16 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 17.7 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.041 (ranging from 3.0304 AU at periapsis to 3.2896 AU at apoapsis), the planet experiences minimal orbital distance variation.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.100 R⊕, HD 11964 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 11964 is classified as a solar-type yellow star of spectral type G9 V CN+1 with an effective photospheric temperature of 5,303 K, a radius of 2.0097 R☉, a mass of 0.91 M☉, an estimated bolometric luminosity of 2.866 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.45 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, HD 11964 shines at apparent V-band magnitude 6.415 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 11964 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 11964 b sharing its stellar neighborhood alongside HD 11964 c.
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 11964 |
| Spectral Type | G9 V CN+1 |
| Effective Temp (Teff) | 5,303 K |
| Stellar Radius | 2.0097 R☉ |
| Stellar Mass | 0.9100 M☉ |
| Bolometric Luminosity | 2.866 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 7.450 Gyr |
| Apparent Magnitude | V: 6.415 · G: 6.209 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.160000 AU |
| Orbital Period | 1945 days |
| Mean Orbital Velocity | 17.7 km/s |
| Orbital Eccentricity (e) | 0.04100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.39 g/cm³ (41.9 km/s vesc) |
| Insolation Flux | 0.2882 S⊕ (~392 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 109.400 LY (33.537 pc) |