HIP 105854 b
Astrophysical Synthesis & Habitability Characterization
HIP 105854 b is a confirmed gas giant exoplanet orbiting the star HIP 105854, located approximately 256.5 light-years (78.64 parsecs) from the Solar System. First announced in 2014 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.6 Earth radii (1.12 Jupiter radii) and has a measured mass of 2606.1 Earth masses (8.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 7.18 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 16.42 g⊕ (161.03 m/s²), and an escape velocity of 160.9 km/s.
In its orbital architecture around HIP 105854, HIP 105854 b completes one full revolution every 184.2 Earth days at a semi-major axis of 0.81 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 47.8 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.02 (ranging from 0.7938 AU at periapsis to 0.8262 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 822 K (+549°C / +1020°F) and receiving 71.29 S⊕ (~97,026 W/m²), HIP 105854 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 105854 is classified as an orange K-type star of spectral type K2 III with an effective photospheric temperature of 4,780 K, a radius of 10.3051 R☉, a mass of 2.1 M☉, an estimated bolometric luminosity of 49.74 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.31 dex (metal-rich relative to the Sun). From Earth, HIP 105854 shines at apparent V-band magnitude 5.64 (visible to the unaided human eye under dark skies) 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 105854 |
| Spectral Type | K2 III |
| Effective Temp (Teff) | 4,780 K |
| Stellar Radius | 10.3051 R☉ |
| Stellar Mass | 2.1000 M☉ |
| Bolometric Luminosity | 49.74 L☉ |
| Metallicity [Fe/H] | 0.310 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 5.640 · G: 5.286 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.810000 AU |
| Orbital Period | 184.2 days |
| Mean Orbital Velocity | 47.8 km/s |
| Orbital Eccentricity (e) | 0.02000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 7.18 g/cm³ (160.9 km/s vesc) |
| Insolation Flux | 71.2902 S⊕ (~97,026 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 256.500 LY (78.638 pc) |