HD 168443 c
Astrophysical Synthesis & Habitability Characterization
HD 168443 c 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 2000 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 12.2 Earth radii (1.09 Jupiter radii) and has a measured mass of 5500.338 Earth masses (17.31 Jupiter masses). Combining its mass and radius yields a mean bulk density of 16.7 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 36.95 g⊕ (362.36 m/s²), and an escape velocity of 237.5 km/s.
In its orbital architecture around HD 168443, HD 168443 c completes one full revolution every 1753.11 Earth days (4.8Julian years) at a semi-major axis of 2.842 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 17.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.21 carries the world between 2.2452 AU at periapsis and 3.4388 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.200 R⊕, HD 168443 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
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 c sharing its stellar neighborhood alongside HD 168443 b.
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) | 2.842000 AU |
| Orbital Period | 1753.11 days |
| Mean Orbital Velocity | 17.6 km/s |
| Orbital Eccentricity (e) | 0.21000 |
| Orbital Inclination (i) | 91.2180° |
| Mean Bulk Density | 16.7 g/cm³ (237.5 km/s vesc) |
| Insolation Flux | 0.2987 S⊕ (~407 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 129.200 LY (39.625 pc) |