51 Eri b

Astrophysical Synthesis & Habitability Characterization

51 Eri b is a confirmed gas giant exoplanet orbiting the star 51 Eri, located approximately 97.1 light-years (29.76 parsecs) from the Solar System. First announced in 2015 by Gemini Observatory using the Imaging detection technique (resolved directly via high-contrast coronagraphic or interferometric imaging), this world has a minimum or true mass of 3464.33 Earth masses (10.9 M♃), while its physical transit radius has not yet been geometrically observed.

In its orbital architecture around 51 Eri, 51 Eri b completes one full revolution every 9100 Earth days (24.91Julian years) at a semi-major axis of 10.4 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 12.4 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.57, swinging from 4.472 AU at periapsis out to 16.328 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 807 K (+534°C / +993°F) and receiving 0.05 S⊕ (~72 W/m²), 51 Eri b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star 51 Eri is classified as a warm F-type star of spectral type F0 IV with an effective photospheric temperature of 7,422 K, a radius of 1.45 R☉, a mass of 1.75 M☉, an estimated bolometric luminosity of 5.724 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.023 Gyr and a metallicity of [Fe/H] = 0.13 dex (metal-rich relative to the Sun). From Earth, 51 Eri shines at apparent V-band magnitude 5.211 (visible to the unaided human eye under dark skies) in the Southern celestial hemisphere.

Discovery Facility: Gemini Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).