Epsilon Eridani


Epsilon Eridani (BD−09°697) is a star in the southern constellation Eridanus, along a declination 9.46° south of the celestial equator. This allows it to be viewed from most of Earth’s surface. At a distance of 10.5 light years (ly), it has an apparent magnitude of 3.73. It is the third closest individual star or star system visible to the unaided eye. Its age is estimated at less than a billion years. Because of its youth, Epsilon Eridani has a higher level of magnetic activity than the present-day Sun, with a stellar wind 30 times as strong. Its rotation period is 11.2 days at the equator. Epsilon Eridani is smaller and less massive than the Sun, and has a comparatively lower level of elements heavier than helium. It is a main-sequence star of spectral class K2, which means that energy generated at the core through nuclear fusion of hydrogen is emitted from the surface at a temperature of about 5,000 K, giving it an orange hue.

The motion of Epsilon Eridani along the line of sight to Earth, known as the radial velocity, has been regularly observed since a time before the Early Space Era. Periodic changes in this data yielded evidence of a giant planet orbiting Epsilon Eridani, so it was no surprise when it was found within the system during a system survey. This planet is named simply as Epsilon Eridani b. This planet orbits with a period of about 7 years at a mean separation of 3.4 astronomical units (AU) with it’s star. It is a hydrogen gas giant with a mass about 80% of that of the planet Jupiter.

The system includes two belts of rocky asteroids: one at about 3 AU and a second at about 20 AU, whose structure is maintained by a second planet, Epsilon Eridani C. Epsilon Eradani C is an ice giant. Epsilon Eridani harbors an extensive outer debris disk of remnant planetesimals left over from the system’s formation. On the inner edge of the system, .56 AU from the star, is a third planet which is a terrestrial world best described as a primitive Earth resembling the archean period of our own planet of about 2.5 billion years ago. It has a high potential to develop primitive life at some point in the future.

Its nearest neighbor, the binary star system Luyten 726-8, will have a close encounter with Epsilon Eridani in approximately 31,500 years when they will be separated by about 0.93 ly.

Epsilon Eradani has a small research station and a SAN base. Though most of the activity in the system itself is research with the base providing a trade hub and defensive installation.

Epsilon Eridani

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