HD 76700 b
Astrophysical Synthesis & Habitability Characterization
HD 76700 b is a confirmed gas giant exoplanet orbiting the star HD 76700, located approximately 198.6 light-years (60.88 parsecs) from the Solar System. First announced in 2002 by Anglo-Australian Telescope using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 9.6 Earth radii (0.86 Jupiter radii) and has a measured mass of 66.744 Earth masses (0.21 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.42 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.72 g⊕ (7.06 m/s²), and an escape velocity of 29.5 km/s.
In its orbital architecture around HD 76700, HD 76700 b completes one full revolution every 3.971 Earth days at a semi-major axis of 0.05 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 137 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.09 carries the world between 0.0455 AU at periapsis and 0.0545 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1425 K (+1152°C / +2106°F) and receiving 723.18 S⊕ (~984,253 W/m²), HD 76700 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 76700 is classified as a solar-type yellow star of spectral type G6 V with an effective photospheric temperature of 5,644 K, a radius of 1.37 R☉, a mass of 0.99 M☉, an estimated bolometric luminosity of 1.709 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = 0.31 dex (metal-rich relative to the Sun). From Earth, HD 76700 shines at apparent V-band magnitude 8.16 (accessible to binoculars and small amateur telescopes) in the Southern 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: Anglo-Australian Telescope · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 76700 |
| Spectral Type | G6 V |
| Effective Temp (Teff) | 5,644 K |
| Stellar Radius | 1.3700 R☉ |
| Stellar Mass | 0.9900 M☉ |
| Bolometric Luminosity | 1.709 L☉ |
| Metallicity [Fe/H] | 0.310 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 8.160 · G: 7.973 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050000 AU |
| Orbital Period | 3.971 days |
| Mean Orbital Velocity | 137 km/s |
| Orbital Eccentricity (e) | 0.09000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.42 g/cm³ (29.5 km/s vesc) |
| Insolation Flux | 723.1837 S⊕ (~984,253 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 198.600 LY (60.883 pc) |