HD 1666 b
Astrophysical Synthesis & Habitability Characterization
HD 1666 b is a confirmed gas giant exoplanet orbiting the star HD 1666, located approximately 384.6 light-years (117.91 parsecs) from the Solar System. First announced in 2015 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.7 Earth radii (1.13 Jupiter radii) and has a measured mass of 2040 Earth masses (6.42 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5.49 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 12.65 g⊕ (124.05 m/s²), and an escape velocity of 141.8 km/s.
In its orbital architecture around HD 1666, HD 1666 b completes one full revolution every 270 Earth days at a semi-major axis of 0.94 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 37.9 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.63, swinging from 0.3478 AU at periapsis out to 1.5322 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 436 K (+163°C / +325°F) and receiving 6.08 S⊕ (~8,272 W/m²), HD 1666 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 1666 is classified as a warm F-type star of spectral type F7 V with an effective photospheric temperature of 6,317 K, a radius of 1.93 R☉, a mass of 1.5 M☉, an estimated bolometric luminosity of 5.322 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.76 Gyr and a metallicity of [Fe/H] = 0.37 dex (metal-rich relative to the Sun). From Earth, HD 1666 shines at apparent V-band magnitude 8.17 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 1666 |
| Spectral Type | F7 V |
| Effective Temp (Teff) | 6,317 K |
| Stellar Radius | 1.9300 R☉ |
| Stellar Mass | 1.5000 M☉ |
| Bolometric Luminosity | 5.322 L☉ |
| Metallicity [Fe/H] | 0.370 dex |
| Stellar Age | 1.760 Gyr |
| Apparent Magnitude | V: 8.170 · G: 8.051 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.940000 AU |
| Orbital Period | 270 days |
| Mean Orbital Velocity | 37.9 km/s |
| Orbital Eccentricity (e) | 0.63000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.49 g/cm³ (141.8 km/s vesc) |
| Insolation Flux | 6.0778 S⊕ (~8,272 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 384.600 LY (117.908 pc) |