HD 181234 b
Astrophysical Synthesis & Habitability Characterization
HD 181234 b is a confirmed gas giant exoplanet orbiting the star HD 181234, located approximately 155.7 light-years (47.75 parsecs) from the Solar System. First announced in 2019 by La Silla Observatory 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 2980.913 Earth masses (9.38 Jupiter masses). Combining its mass and radius yields a mean bulk density of 8.42 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 19.08 g⊕ (187.11 m/s²), and an escape velocity of 172.7 km/s.
In its orbital architecture around HD 181234, HD 181234 b completes one full revolution every 7593.405 Earth days (20.79Julian years) at a semi-major axis of 7.427 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 10.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.726, swinging from 2.035 AU at periapsis out to 12.819 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 98 K (-175°C / -283°F) and an incident flux of 0.01 S⊕ (~20 W/m²), surface water and volatile species on HD 181234 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 181234 is classified as a solar-type yellow star of spectral type G8 IV with an effective photospheric temperature of 5,386 K, a radius of 1.0594 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.847 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.32 Gyr and a metallicity of [Fe/H] = 0.32 dex (metal-rich relative to the Sun). From Earth, HD 181234 shines at apparent V-band magnitude 8.59 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 181234 |
| Spectral Type | G8 IV |
| Effective Temp (Teff) | 5,386 K |
| Stellar Radius | 1.0594 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.847 L☉ |
| Metallicity [Fe/H] | 0.320 dex |
| Stellar Age | 6.320 Gyr |
| Apparent Magnitude | V: 8.590 · G: 8.369 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 7.427000 AU |
| Orbital Period | 7593.405 days |
| Mean Orbital Velocity | 10.6 km/s |
| Orbital Eccentricity (e) | 0.72600 |
| Orbital Inclination (i) | 98.7320° |
| Mean Bulk Density | 8.42 g/cm³ (172.7 km/s vesc) |
| Insolation Flux | 0.0144 S⊕ (~20 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 155.700 LY (47.746 pc) |