40 Eridani

40 Eridani
Comparison of the habitable zone of 40 Eridani A (here labeled Vulcan) with the habitable zone in our solar system.

40 Eridani (also known as Omicron2 Eridani, or Keid, from the Arabic word qayd, (egg) shells) is a triple star system less than 16.5 light years away from Earth. It is in the constellation Eridanus. The primary star of the system, 40 Eridani A, is easily visible to the naked eye. The pair 40 Eridani B/C was discovered on January 31, 1783, by William Herschel. It was again observed by Friedrich Georg Wilhelm Struve in 1825 and by Otto Wilhelm von Struve in 1851. In 1910, it was discovered that although component B was a faint star, it was white in color. This meant that it had to be a small star; in fact it was a white dwarf, the first discovered.

40 Eridani A is a main sequence dwarf of spectral type K1. Its two companion stars, 40 Eridani B and 40 Eridani C, are a 9th magnitude white dwarf (spectral type DA4) and an 11th magnitude red dwarf flare star (spectral type M4.5e) which has the variable star designation DY Eridani. Presumably, while B was a main sequence star, it was the most massive member of the system, but ejected most of its mass before it became a white dwarf. B and C orbit each other approximately 400 astronomical units from the primary star, A.Their orbit has a semimajor axis of 35 AU (which is also the approximate average distance between B and C) and is rather elliptical (eccentricity 0.410).

40 Eridani in Space Opera

  • Star Trek? film and television franchise. 40 Eridani A is the location of the planet Vulcan?, home of the Vulcan? species. Although this was never stated on any TV show or film, both the authorized Star Trek book Star Trek: Star Charts and Gene Roddenberry? give this location. In addition, Commander Tucker's statement in Star Trek: Enterprise? that Vulcan is 16 light years from Earth supports this as 40 Eridani A is 16.39ly from Sol.
  • In the RPG GDW's 2300 AD?, Montana? (Spanish: Montaña) is the second planet of Omicron2 Eridani, a garden habitable world, and it houses the Mexico-Argentina joint colony of Montana. While Argentina and Mexico originally placed two separate colonies within cooperating distance of each other, the distinctions have long since vanished. The Argentines first settled the continent of Chimborazo, while the Mexicans settled West Island, the largest of the 3 main islands of the planet. Omicron2 Eridani is part of the Latin systems.
  • In Alliance Union Universe the system is stated to have a station.
  • In Dune Universe the system goes by the name Rodale and later Alklurops. The ninth planet has the name Ix.

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