HD 168443 b
Astrophysical Synthesis & Habitability Characterization
HD 168443 b is a confirmed gas giant exoplanet orbiting the star HD 168443, located approximately 129.2 light-years (39.63 parsecs) from the Solar System. First announced in 1998 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.6 Earth radii (1.12 Jupiter radii) and has a measured mass of 2424.395 Earth masses (7.63 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.68 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 15.27 g⊕ (149.75 m/s²), and an escape velocity of 155.2 km/s.
In its orbital architecture around HD 168443, HD 168443 b completes one full revolution every 58.112 Earth days at a semi-major axis of 0.292 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 54.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.53, swinging from 0.1372 AU at periapsis out to 0.4468 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 641 K (+368°C / +694°F) and receiving 28.29 S⊕ (~38,508 W/m²), HD 168443 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 168443 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 5,491 K, a radius of 1.7115 R☉, a mass of 0.98 M☉, an estimated bolometric luminosity of 2.389 L☉. Stellar evolution modeling indicates an estimated stellar age of 11.08 Gyr and a metallicity of [Fe/H] = 0.04 dex (near-solar heavy-element abundance). From Earth, HD 168443 shines at apparent V-band magnitude 6.921 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 168443 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 168443 b sharing its stellar neighborhood alongside HD 168443 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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 168443 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 5,491 K |
| Stellar Radius | 1.7115 R☉ |
| Stellar Mass | 0.9800 M☉ |
| Bolometric Luminosity | 2.389 L☉ |
| Metallicity [Fe/H] | 0.040 dex |
| Stellar Age | 11.080 Gyr |
| Apparent Magnitude | V: 6.921 · G: 6.732 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.292000 AU |
| Orbital Period | 58.112 days |
| Mean Orbital Velocity | 54.7 km/s |
| Orbital Eccentricity (e) | 0.53000 |
| Orbital Inclination (i) | 92.0000° |
| Mean Bulk Density | 6.68 g/cm³ (155.2 km/s vesc) |
| Insolation Flux | 28.2942 S⊕ (~38,508 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 129.200 LY (39.625 pc) |