HIP 8541 b
Astrophysical Synthesis & Habitability Characterization
HIP 8541 b is a confirmed gas giant exoplanet orbiting the star HIP 8541, located approximately 505.9 light-years (155.12 parsecs) from the Solar System. First announced in 2016 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 2451.728 Earth masses (7.71 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.76 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 15.44 g⊕ (151.41 m/s²), and an escape velocity of 156 km/s.
In its orbital architecture around HIP 8541, HIP 8541 b completes one full revolution every 1852.144 Earth days (5.07Julian years) at a semi-major axis of 3.729 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 21.9 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.36, swinging from 2.3866 AU at periapsis out to 5.0714 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.600 R⊕, HIP 8541 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 HIP 8541 is classified as an orange K-type star of spectral type K2 III/IV with an effective photospheric temperature of 4,672 K, a radius of 6.84 R☉, a mass of 2.009 M☉, an estimated bolometric luminosity of 19.999 L☉. Stellar evolution modeling indicates an estimated stellar age of 10.97 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, HIP 8541 shines at apparent V-band magnitude 7.88 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HIP 8541 system is a multi-planet architecture hosting 2 confirmed worlds, with HIP 8541 b sharing its stellar neighborhood alongside HD 11343 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HIP 8541 |
| Spectral Type | K2 III/IV |
| Effective Temp (Teff) | 4,672 K |
| Stellar Radius | 6.8400 R☉ |
| Stellar Mass | 2.0090 M☉ |
| Bolometric Luminosity | 19.999 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 10.970 Gyr |
| Apparent Magnitude | V: 7.880 · G: 7.561 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.729000 AU |
| Orbital Period | 1852.144 days |
| Mean Orbital Velocity | 21.9 km/s |
| Orbital Eccentricity (e) | 0.36000 |
| Orbital Inclination (i) | 90.9040° |
| Mean Bulk Density | 6.76 g/cm³ (156 km/s vesc) |
| Insolation Flux | 1.4683 S⊕ (~1,998 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 505.900 LY (155.121 pc) |