HD 166724 b
Astrophysical Synthesis & Habitability Characterization
HD 166724 b is a confirmed gas giant exoplanet orbiting the star HD 166724, located approximately 147.2 light-years (45.13 parsecs) from the Solar System. First announced in 2012 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 Earth radii (1.16 Jupiter radii) and has a measured mass of 1207.748 Earth masses (3.8 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.03 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.15 g⊕ (70.12 m/s²), and an escape velocity of 107.8 km/s.
In its orbital architecture around HD 166724, HD 166724 b completes one full revolution every 5144 Earth days (14.08Julian years) at a semi-major axis of 5.42 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 11.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.734, swinging from 1.4417 AU at periapsis out to 9.3983 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 95 K (-178°C / -288°F) and an incident flux of 0.01 S⊕ (~14 W/m²), surface water and volatile species on HD 166724 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 166724 is classified as an orange K-type star of spectral type K0 IV-V with an effective photospheric temperature of 5,127 K, a radius of 0.7975 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.394 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, HD 166724 shines at apparent V-band magnitude 9.33 (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 166724 |
| Spectral Type | K0 IV-V |
| Effective Temp (Teff) | 5,127 K |
| Stellar Radius | 0.7975 R☉ |
| Stellar Mass | 0.8100 M☉ |
| Bolometric Luminosity | 0.394 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 9.330 · G: 9.069 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 5.420000 AU |
| Orbital Period | 5144 days |
| Mean Orbital Velocity | 11.5 km/s |
| Orbital Eccentricity (e) | 0.73400 |
| Orbital Inclination (i) | 68.0000° |
| Mean Bulk Density | 3.03 g/cm³ (107.8 km/s vesc) |
| Insolation Flux | 0.0105 S⊕ (~14 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 147.200 LY (45.134 pc) |