HIP 81208 C b
Astrophysical Synthesis & Habitability Characterization
HIP 81208 C b is a confirmed gas giant exoplanet orbiting the star HIP 81208 C, located approximately 481.2 light-years (147.53 parsecs) from the Solar System. First announced in 2023 by Paranal Observatory using the Imaging detection technique (resolved directly via high-contrast coronagraphic or interferometric imaging), this world measures 12.3 Earth radii (1.1 Jupiter radii) and has a measured mass of 4703.86 Earth masses (14.8 Jupiter masses). Combining its mass and radius yields a mean bulk density of 13.94 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 31.09 g⊕ (304.89 m/s²), and an escape velocity of 218.8 km/s.
In its orbital architecture around HIP 81208 C, HIP 81208 C b completes one full revolution every 104100 Earth days (285.01Julian years) at a semi-major axis of 23.04 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 2.4 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 2050 K (+1777°C / +3231°F), HIP 81208 C b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HIP 81208 C is classified as a low-mass red dwarf of spectral type M with a mass of 0.135 M☉. Stellar evolution modeling indicates an estimated stellar age of 0.017 Gyr.
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: Paranal Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 81208 C |
| Spectral Type | M |
| Effective Temp (Teff) | — |
| Stellar Radius | — |
| Stellar Mass | 0.1350 M☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 0.017 Gyr |
| Apparent Magnitude | — |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 23.040000 AU |
| Orbital Period | 104100 days |
| Mean Orbital Velocity | 2.4 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 13.94 g/cm³ (218.8 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 481.200 LY (147.533 pc) |