HD 6718 b
Astrophysical Synthesis & Habitability Characterization
HD 6718 b is a confirmed gas giant exoplanet orbiting the star HD 6718, located approximately 167.5 light-years (51.34 parsecs) from the Solar System. First announced in 2009 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 762.788 Earth masses (2.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.79 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.31 g⊕ (42.27 m/s²), and an escape velocity of 84.7 km/s.
In its orbital architecture around HD 6718, HD 6718 b completes one full revolution every 2476 Earth days (6.78Julian years) at a semi-major axis of 3.53 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 15.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.06 carries the world between 3.3182 AU at periapsis and 3.7418 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 149 K (-124°C / -191°F) and an incident flux of 0.09 S⊕ (~123 W/m²), surface water and volatile species on HD 6718 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 6718 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,746 K, a radius of 1.02 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 1.018 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, HD 6718 shines at apparent V-band magnitude 8.45 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 6718 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,746 K |
| Stellar Radius | 1.0200 R☉ |
| Stellar Mass | 0.9600 M☉ |
| Bolometric Luminosity | 1.018 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.450 · G: 8.281 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.530000 AU |
| Orbital Period | 2476 days |
| Mean Orbital Velocity | 15.5 km/s |
| Orbital Eccentricity (e) | 0.06000 |
| Orbital Inclination (i) | 51.4000° |
| Mean Bulk Density | 1.79 g/cm³ (84.7 km/s vesc) |
| Insolation Flux | 0.0907 S⊕ (~123 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 167.500 LY (51.344 pc) |