HD 108874 b
Astrophysical Synthesis & Habitability Characterization
HD 108874 b is a confirmed gas giant exoplanet orbiting the star HD 108874, located approximately 194.1 light-years (59.52 parsecs) from the Solar System. First announced in 2002 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 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 451.319 Earth masses (1.42 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.99 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.44 g⊕ (23.93 m/s²), and an escape velocity of 64.4 km/s.
In its orbital architecture around HD 108874, HD 108874 b completes one full revolution every 394.481 Earth days (1.08Julian years) at a semi-major axis of 1.04 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 28.7 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.13 carries the world between 0.9048 AU at periapsis and 1.1752 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.600 R⊕, HD 108874 b 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 108874 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 5,600 K, a radius of 1.05 R☉, a mass of 1.1 M☉, an estimated bolometric luminosity of 0.973 L☉. Stellar evolution modeling indicates an estimated stellar age of 8 Gyr and a metallicity of [Fe/H] = 0.26 dex (metal-rich relative to the Sun). From Earth, HD 108874 shines at apparent V-band magnitude 8.76 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The HD 108874 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 108874 b sharing its stellar neighborhood alongside HD 108874 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 108874 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 5,600 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.1000 M☉ |
| Bolometric Luminosity | 0.973 L☉ |
| Metallicity [Fe/H] | 0.260 dex |
| Stellar Age | 8.000 Gyr |
| Apparent Magnitude | V: 8.760 · G: 8.575 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.040000 AU |
| Orbital Period | 394.481 days |
| Mean Orbital Velocity | 28.7 km/s |
| Orbital Eccentricity (e) | 0.13000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.99 g/cm³ (64.4 km/s vesc) |
| Insolation Flux | 0.9230 S⊕ (~1,256 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 194.100 LY (59.518 pc) |