HD 38529 b
Astrophysical Synthesis & Habitability Characterization
HD 38529 b 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 14.1 Earth radii (1.26 Jupiter radii) and has a measured mass of 206.588 Earth masses (0.65 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.41 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 42.8 km/s.
In its orbital architecture around HD 38529, HD 38529 b completes one full revolution every 14.31 Earth days at a semi-major axis of 0.115 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.256, swinging from 0.0856 AU at periapsis out to 0.1444 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1369 K (+1096°C / +2005°F) and receiving 516.18 S⊕ (~702,527 W/m²), HD 38529 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
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 b sharing its stellar neighborhood alongside HD 38529 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: 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) | 0.115000 AU |
| Orbital Period | 14.31 days |
| Mean Orbital Velocity | 87.4 km/s |
| Orbital Eccentricity (e) | 0.25600 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.41 g/cm³ (42.8 km/s vesc) |
| Insolation Flux | 516.1847 S⊕ (~702,527 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 138.100 LY (42.354 pc) |