HD 38529 c
Astrophysical Synthesis & Habitability Characterization
HD 38529 c is a confirmed gas giant exoplanet orbiting the star HD 38529, located approximately 138.1 light-years (42.35 parsecs) from the Solar System. First announced in 2000 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.5 Earth radii (1.12 Jupiter radii) and has a measured mass of 3299.059 Earth masses (10.38 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.31 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 21.11 g⊕ (207.02 m/s²), and an escape velocity of 181.7 km/s.
In its orbital architecture around HD 38529, HD 38529 c completes one full revolution every 2127.606 Earth days (5.83Julian years) at a semi-major axis of 3.226 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 16.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.357, swinging from 2.0743 AU at periapsis out to 4.3777 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.500 R⊕, HD 38529 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 38529 is classified as a solar-type yellow star of spectral type G4 IV with an effective photospheric temperature of 5,697 K, a radius of 2.8578 R☉, a mass of 0.98 M☉, an estimated bolometric luminosity of 7.719 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.5 Gyr and a metallicity of [Fe/H] = 0.51 dex (metal-rich relative to the Sun). From Earth, HD 38529 shines at apparent V-band magnitude 5.928 (visible to the unaided human eye under dark skies) in the Northern celestial hemisphere. The HD 38529 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 38529 c sharing its stellar neighborhood alongside HD 38529 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 38529 |
| Spectral Type | G4 IV |
| Effective Temp (Teff) | 5,697 K |
| Stellar Radius | 2.8578 R☉ |
| Stellar Mass | 0.9800 M☉ |
| Bolometric Luminosity | 7.719 L☉ |
| Metallicity [Fe/H] | 0.510 dex |
| Stellar Age | 4.500 Gyr |
| Apparent Magnitude | V: 5.928 · G: 5.748 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.226000 AU |
| Orbital Period | 2127.606 days |
| Mean Orbital Velocity | 16.5 km/s |
| Orbital Eccentricity (e) | 0.35700 |
| Orbital Inclination (i) | 104.5590° |
| Mean Bulk Density | 9.31 g/cm³ (181.7 km/s vesc) |
| Insolation Flux | 0.6560 S⊕ (~893 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 138.100 LY (42.354 pc) |