HD 200964 b
Astrophysical Synthesis & Habitability Characterization
HD 200964 b is a confirmed gas giant exoplanet orbiting the star HD 200964, located approximately 236.8 light-years (72.59 parsecs) from the Solar System. First announced in 2010 by Lick Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.5 Earth radii (1.2 Jupiter radii) and has a measured mass of 508.21 Earth masses (1.6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.14 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.79 g⊕ (27.36 m/s²), and an escape velocity of 68.6 km/s.
In its orbital architecture around HD 200964, HD 200964 b completes one full revolution every 606.3 Earth days (1.66Julian years) at a semi-major axis of 1.565 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 28.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.087 carries the world between 1.4288 AU at periapsis and 1.7012 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 426 K (+153°C / +307°F) and receiving 4.73 S⊕ (~6,439 W/m²), HD 200964 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 200964 is classified as a solar-type yellow star of spectral type G8 IV with an effective photospheric temperature of 4,982 K, a radius of 4.92 R☉, a mass of 1.39 M☉, an estimated bolometric luminosity of 13.379 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = -0.15 dex (metal-poor relative to the Sun). From Earth, HD 200964 shines at apparent V-band magnitude 6.486 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 200964 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 200964 b sharing its stellar neighborhood alongside HD 200964 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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 200964 |
| Spectral Type | G8 IV |
| Effective Temp (Teff) | 4,982 K |
| Stellar Radius | 4.9200 R☉ |
| Stellar Mass | 1.3900 M☉ |
| Bolometric Luminosity | 13.379 L☉ |
| Metallicity [Fe/H] | -0.150 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 6.486 · G: 6.237 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.565000 AU |
| Orbital Period | 606.3 days |
| Mean Orbital Velocity | 28.1 km/s |
| Orbital Eccentricity (e) | 0.08700 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.14 g/cm³ (68.6 km/s vesc) |
| Insolation Flux | 4.7312 S⊕ (~6,439 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 236.800 LY (72.592 pc) |