eps Eri b
Astrophysical Synthesis & Habitability Characterization
eps Eri b is a confirmed gas giant exoplanet orbiting the star eps Eri, located approximately 10.4 light-years (3.2 parsecs) from the Solar System. First announced in 2000 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 317.828 Earth masses (1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.67 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.67 g⊕ (16.38 m/s²), and an escape velocity of 53.7 km/s.
In its orbital architecture around eps Eri, eps Eri b completes one full revolution every 2680 Earth days (7.34Julian years) at a semi-major axis of 3.53 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 14.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.06 carries the world between 3.3182 AU at periapsis and 3.7418 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 112 K (-161°C / -258°F) and an incident flux of 0.03 S⊕ (~42 W/m²), surface water and volatile species on eps Eri b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star eps Eri is classified as an orange K-type star of spectral type K2 V with an effective photospheric temperature of 5,020 K, a radius of 0.7591 R☉, a mass of 0.82 M☉, an estimated bolometric luminosity of 0.328 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.6 Gyr and a metallicity of [Fe/H] = -0.13 dex (metal-poor relative to the Sun). From Earth, eps Eri shines at apparent V-band magnitude 3.715 (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 | eps Eri |
| Spectral Type | K2 V |
| Effective Temp (Teff) | 5,020 K |
| Stellar Radius | 0.7591 R☉ |
| Stellar Mass | 0.8200 M☉ |
| Bolometric Luminosity | 0.328 L☉ |
| Metallicity [Fe/H] | -0.130 dex |
| Stellar Age | 0.600 Gyr |
| Apparent Magnitude | V: 3.715 · G: 3.477 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.530000 AU |
| Orbital Period | 2680 days |
| Mean Orbital Velocity | 14.3 km/s |
| Orbital Eccentricity (e) | 0.06000 |
| Orbital Inclination (i) | 40.0000° |
| Mean Bulk Density | 0.67 g/cm³ (53.7 km/s vesc) |
| Insolation Flux | 0.0306 S⊕ (~42 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 10.400 LY (3.203 pc) |