HD 100508 b
Astrophysical Synthesis & Habitability Characterization
HD 100508 b is a confirmed gas giant exoplanet orbiting the star HD 100508, located approximately 106.8 light-years (32.76 parsecs) from the Solar System. First announced in 2026 by Las Campanas Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 381.394 Earth masses (1.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.82 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.03 g⊕ (19.91 m/s²), and an escape velocity of 59 km/s.
In its orbital architecture around HD 100508, HD 100508 b completes one full revolution every 5681 Earth days (15.55Julian years) at a semi-major axis of 6.11 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 11.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.42, swinging from 3.5438 AU at periapsis out to 8.6762 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 107 K (-166°C / -267°F) and an incident flux of 0.02 S⊕ (~29 W/m²), surface water and volatile species on HD 100508 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 100508 is classified as an orange K-type star of spectral type K1 IV with an effective photospheric temperature of 5,419 K, a radius of 1.0179 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.802 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.33 dex (metal-rich relative to the Sun). From Earth, HD 100508 shines at apparent V-band magnitude 7.74 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere.
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: Las Campanas Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 100508 |
| Spectral Type | K1 IV |
| Effective Temp (Teff) | 5,419 K |
| Stellar Radius | 1.0179 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.802 L☉ |
| Metallicity [Fe/H] | 0.330 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 7.740 · G: 7.525 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 6.110000 AU |
| Orbital Period | 5681 days |
| Mean Orbital Velocity | 11.7 km/s |
| Orbital Eccentricity (e) | 0.42000 |
| Orbital Inclination (i) | 62.0000° |
| Mean Bulk Density | 0.82 g/cm³ (59 km/s vesc) |
| Insolation Flux | 0.0216 S⊕ (~29 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 106.800 LY (32.755 pc) |